"""
Collection of utilities to manipulate structured arrays.
Most of these functions were initially implemented by John Hunter for
matplotlib. They have been rewritten and extended for convenience.
"""
import itertools
import numpy as np
import numpy.ma as ma
from numpy import ndarray
from numpy.ma import MaskedArray
from numpy.ma.mrecords import MaskedRecords
from numpy._core.overrides import array_function_dispatch
from numpy._core.records import recarray
from numpy.lib._iotools import _is_string_like
_check_fill_value = np.ma.core._check_fill_value
__all__ = [
'append_fields', 'apply_along_fields', 'assign_fields_by_name',
'drop_fields', 'find_duplicates', 'flatten_descr',
'get_fieldstructure', 'get_names', 'get_names_flat',
'join_by', 'merge_arrays', 'rec_append_fields',
'rec_drop_fields', 'rec_join', 'recursive_fill_fields',
'rename_fields', 'repack_fields', 'require_fields',
'stack_arrays', 'structured_to_unstructured', 'unstructured_to_structured',
]
def _recursive_fill_fields_dispatcher(input, output):
return (input, output)
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@array_function_dispatch(_recursive_fill_fields_dispatcher)
def recursive_fill_fields(input, output):
"""
Fills fields from output with fields from input,
with support for nested structures.
Parameters
----------
input : ndarray
Input array.
output : ndarray
Output array.
Notes
-----
* `output` should be at least the same size as `input`
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> a = np.array([(1, 10.), (2, 20.)], dtype=[('A', np.int64), ('B', np.float64)])
>>> b = np.zeros((3,), dtype=a.dtype)
>>> rfn.recursive_fill_fields(a, b)
array([(1, 10.), (2, 20.), (0, 0.)], dtype=[('A', '<i8'), ('B', '<f8')])
"""
newdtype = output.dtype
for field in newdtype.names:
try:
current = input[field]
except ValueError:
continue
if current.dtype.names is not None:
recursive_fill_fields(current, output[field])
else:
output[field][:len(current)] = current
return output
def _get_fieldspec(dtype):
"""
Produce a list of name/dtype pairs corresponding to the dtype fields
Similar to dtype.descr, but the second item of each tuple is a dtype, not a
string. As a result, this handles subarray dtypes
Can be passed to the dtype constructor to reconstruct the dtype, noting that
this (deliberately) discards field offsets.
Examples
--------
>>> dt = np.dtype([(('a', 'A'), np.int64), ('b', np.double, 3)])
>>> dt.descr
[(('a', 'A'), '<i8'), ('b', '<f8', (3,))]
>>> _get_fieldspec(dt)
[(('a', 'A'), dtype('int64')), ('b', dtype(('<f8', (3,))))]
"""
if dtype.names is None:
# .descr returns a nameless field, so we should too
return [('', dtype)]
else:
fields = ((name, dtype.fields[name]) for name in dtype.names)
# keep any titles, if present
return [
(name if len(f) == 2 else (f[2], name), f[0])
for name, f in fields
]
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def get_names(adtype):
"""
Returns the field names of the input datatype as a tuple. Input datatype
must have fields otherwise error is raised.
Parameters
----------
adtype : dtype
Input datatype
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> rfn.get_names(np.empty((1,), dtype=[('A', int)]).dtype)
('A',)
>>> rfn.get_names(np.empty((1,), dtype=[('A',int), ('B', float)]).dtype)
('A', 'B')
>>> adtype = np.dtype([('a', int), ('b', [('ba', int), ('bb', int)])])
>>> rfn.get_names(adtype)
('a', ('b', ('ba', 'bb')))
"""
listnames = []
names = adtype.names
for name in names:
current = adtype[name]
if current.names is not None:
listnames.append((name, tuple(get_names(current))))
else:
listnames.append(name)
return tuple(listnames)
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def get_names_flat(adtype):
"""
Returns the field names of the input datatype as a tuple. Input datatype
must have fields otherwise error is raised.
Nested structure are flattened beforehand.
Parameters
----------
adtype : dtype
Input datatype
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> rfn.get_names_flat(np.empty((1,), dtype=[('A', int)]).dtype) is None
False
>>> rfn.get_names_flat(np.empty((1,), dtype=[('A',int), ('B', str)]).dtype)
('A', 'B')
>>> adtype = np.dtype([('a', int), ('b', [('ba', int), ('bb', int)])])
>>> rfn.get_names_flat(adtype)
('a', 'b', 'ba', 'bb')
"""
listnames = []
names = adtype.names
for name in names:
listnames.append(name)
current = adtype[name]
if current.names is not None:
listnames.extend(get_names_flat(current))
return tuple(listnames)
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def flatten_descr(ndtype):
"""
Flatten a structured data-type description.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> ndtype = np.dtype([('a', '<i4'), ('b', [('ba', '<f8'), ('bb', '<i4')])])
>>> rfn.flatten_descr(ndtype)
(('a', dtype('int32')), ('ba', dtype('float64')), ('bb', dtype('int32')))
"""
names = ndtype.names
if names is None:
return (('', ndtype),)
else:
descr = []
for field in names:
(typ, _) = ndtype.fields[field]
if typ.names is not None:
descr.extend(flatten_descr(typ))
else:
descr.append((field, typ))
return tuple(descr)
def _zip_dtype(seqarrays, flatten=False):
newdtype = []
if flatten:
for a in seqarrays:
newdtype.extend(flatten_descr(a.dtype))
else:
for a in seqarrays:
current = a.dtype
if current.names is not None and len(current.names) == 1:
# special case - dtypes of 1 field are flattened
newdtype.extend(_get_fieldspec(current))
else:
newdtype.append(('', current))
return np.dtype(newdtype)
def _zip_descr(seqarrays, flatten=False):
"""
Combine the dtype description of a series of arrays.
Parameters
----------
seqarrays : sequence of arrays
Sequence of arrays
flatten : {boolean}, optional
Whether to collapse nested descriptions.
"""
return _zip_dtype(seqarrays, flatten=flatten).descr
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def get_fieldstructure(adtype, lastname=None, parents=None,):
"""
Returns a dictionary with fields indexing lists of their parent fields.
This function is used to simplify access to fields nested in other fields.
Parameters
----------
adtype : np.dtype
Input datatype
lastname : optional
Last processed field name (used internally during recursion).
parents : dictionary
Dictionary of parent fields (used interbally during recursion).
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> ndtype = np.dtype([('A', int),
... ('B', [('BA', int),
... ('BB', [('BBA', int), ('BBB', int)])])])
>>> rfn.get_fieldstructure(ndtype)
... # XXX: possible regression, order of BBA and BBB is swapped
{'A': [], 'B': [], 'BA': ['B'], 'BB': ['B'], 'BBA': ['B', 'BB'], 'BBB': ['B', 'BB']}
"""
if parents is None:
parents = {}
names = adtype.names
for name in names:
current = adtype[name]
if current.names is not None:
if lastname:
parents[name] = [lastname, ]
else:
parents[name] = []
parents.update(get_fieldstructure(current, name, parents))
else:
lastparent = [_ for _ in (parents.get(lastname, []) or [])]
if lastparent:
lastparent.append(lastname)
elif lastname:
lastparent = [lastname, ]
parents[name] = lastparent or []
return parents
def _izip_fields_flat(iterable):
"""
Returns an iterator of concatenated fields from a sequence of arrays,
collapsing any nested structure.
"""
for element in iterable:
if isinstance(element, np.void):
yield from _izip_fields_flat(tuple(element))
else:
yield element
def _izip_fields(iterable):
"""
Returns an iterator of concatenated fields from a sequence of arrays.
"""
for element in iterable:
if (hasattr(element, '__iter__') and
not isinstance(element, str)):
yield from _izip_fields(element)
elif isinstance(element, np.void) and len(tuple(element)) == 1:
# this statement is the same from the previous expression
yield from _izip_fields(element)
else:
yield element
def _izip_records(seqarrays, fill_value=None, flatten=True):
"""
Returns an iterator of concatenated items from a sequence of arrays.
Parameters
----------
seqarrays : sequence of arrays
Sequence of arrays.
fill_value : {None, integer}
Value used to pad shorter iterables.
flatten : {True, False},
Whether to
"""
# Should we flatten the items, or just use a nested approach
if flatten:
zipfunc = _izip_fields_flat
else:
zipfunc = _izip_fields
for tup in itertools.zip_longest(*seqarrays, fillvalue=fill_value):
yield tuple(zipfunc(tup))
def _fix_output(output, usemask=True, asrecarray=False):
"""
Private function: return a recarray, a ndarray, a MaskedArray
or a MaskedRecords depending on the input parameters
"""
if not isinstance(output, MaskedArray):
usemask = False
if usemask:
if asrecarray:
output = output.view(MaskedRecords)
else:
output = ma.filled(output)
if asrecarray:
output = output.view(recarray)
return output
def _fix_defaults(output, defaults=None):
"""
Update the fill_value and masked data of `output`
from the default given in a dictionary defaults.
"""
names = output.dtype.names
(data, mask, fill_value) = (output.data, output.mask, output.fill_value)
for (k, v) in (defaults or {}).items():
if k in names:
fill_value[k] = v
data[k][mask[k]] = v
return output
def _merge_arrays_dispatcher(seqarrays, fill_value=None, flatten=None,
usemask=None, asrecarray=None):
return seqarrays
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@array_function_dispatch(_merge_arrays_dispatcher)
def merge_arrays(seqarrays, fill_value=-1, flatten=False,
usemask=False, asrecarray=False):
"""
Merge arrays field by field.
Parameters
----------
seqarrays : sequence of ndarrays
Sequence of arrays
fill_value : {float}, optional
Filling value used to pad missing data on the shorter arrays.
flatten : {False, True}, optional
Whether to collapse nested fields.
usemask : {False, True}, optional
Whether to return a masked array or not.
asrecarray : {False, True}, optional
Whether to return a recarray (MaskedRecords) or not.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> rfn.merge_arrays((np.array([1, 2]), np.array([10., 20., 30.])))
array([( 1, 10.), ( 2, 20.), (-1, 30.)],
dtype=[('f0', '<i8'), ('f1', '<f8')])
>>> rfn.merge_arrays((np.array([1, 2], dtype=np.int64),
... np.array([10., 20., 30.])), usemask=False)
array([(1, 10.0), (2, 20.0), (-1, 30.0)],
dtype=[('f0', '<i8'), ('f1', '<f8')])
>>> rfn.merge_arrays((np.array([1, 2]).view([('a', np.int64)]),
... np.array([10., 20., 30.])),
... usemask=False, asrecarray=True)
rec.array([( 1, 10.), ( 2, 20.), (-1, 30.)],
dtype=[('a', '<i8'), ('f1', '<f8')])
Notes
-----
* Without a mask, the missing value will be filled with something,
depending on what its corresponding type:
* ``-1`` for integers
* ``-1.0`` for floating point numbers
* ``'-'`` for characters
* ``'-1'`` for strings
* ``True`` for boolean values
* XXX: I just obtained these values empirically
"""
# Only one item in the input sequence ?
if (len(seqarrays) == 1):
seqarrays = np.asanyarray(seqarrays[0])
# Do we have a single ndarray as input ?
if isinstance(seqarrays, (ndarray, np.void)):
seqdtype = seqarrays.dtype
# Make sure we have named fields
if seqdtype.names is None:
seqdtype = np.dtype([('', seqdtype)])
if not flatten or _zip_dtype((seqarrays,), flatten=True) == seqdtype:
# Minimal processing needed: just make sure everything's a-ok
seqarrays = seqarrays.ravel()
# Find what type of array we must return
if usemask:
if asrecarray:
seqtype = MaskedRecords
else:
seqtype = MaskedArray
elif asrecarray:
seqtype = recarray
else:
seqtype = ndarray
return seqarrays.view(dtype=seqdtype, type=seqtype)
else:
seqarrays = (seqarrays,)
else:
# Make sure we have arrays in the input sequence
seqarrays = [np.asanyarray(_m) for _m in seqarrays]
# Find the sizes of the inputs and their maximum
sizes = tuple(a.size for a in seqarrays)
maxlength = max(sizes)
# Get the dtype of the output (flattening if needed)
newdtype = _zip_dtype(seqarrays, flatten=flatten)
# Initialize the sequences for data and mask
seqdata = []
seqmask = []
# If we expect some kind of MaskedArray, make a special loop.
if usemask:
for (a, n) in zip(seqarrays, sizes):
nbmissing = (maxlength - n)
# Get the data and mask
data = a.ravel().__array__()
mask = ma.getmaskarray(a).ravel()
# Get the filling value (if needed)
if nbmissing:
fval = _check_fill_value(fill_value, a.dtype)
if isinstance(fval, (ndarray, np.void)):
if len(fval.dtype) == 1:
fval = fval.item()[0]
fmsk = True
else:
fval = np.array(fval, dtype=a.dtype, ndmin=1)
fmsk = np.ones((1,), dtype=mask.dtype)
else:
fval = None
fmsk = True
# Store an iterator padding the input to the expected length
seqdata.append(itertools.chain(data, [fval] * nbmissing))
seqmask.append(itertools.chain(mask, [fmsk] * nbmissing))
# Create an iterator for the data
data = tuple(_izip_records(seqdata, flatten=flatten))
output = ma.array(np.fromiter(data, dtype=newdtype, count=maxlength),
mask=list(_izip_records(seqmask, flatten=flatten)))
if asrecarray:
output = output.view(MaskedRecords)
else:
# Same as before, without the mask we don't need...
for (a, n) in zip(seqarrays, sizes):
nbmissing = (maxlength - n)
data = a.ravel().__array__()
if nbmissing:
fval = _check_fill_value(fill_value, a.dtype)
if isinstance(fval, (ndarray, np.void)):
if len(fval.dtype) == 1:
fval = fval.item()[0]
else:
fval = np.array(fval, dtype=a.dtype, ndmin=1)
else:
fval = None
seqdata.append(itertools.chain(data, [fval] * nbmissing))
output = np.fromiter(tuple(_izip_records(seqdata, flatten=flatten)),
dtype=newdtype, count=maxlength)
if asrecarray:
output = output.view(recarray)
# And we're done...
return output
def _drop_fields_dispatcher(base, drop_names, usemask=None, asrecarray=None):
return (base,)
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@array_function_dispatch(_drop_fields_dispatcher)
def drop_fields(base, drop_names, usemask=True, asrecarray=False):
"""
Return a new array with fields in `drop_names` dropped.
Nested fields are supported.
.. versionchanged:: 1.18.0
`drop_fields` returns an array with 0 fields if all fields are dropped,
rather than returning ``None`` as it did previously.
Parameters
----------
base : array
Input array
drop_names : string or sequence
String or sequence of strings corresponding to the names of the
fields to drop.
usemask : {False, True}, optional
Whether to return a masked array or not.
asrecarray : string or sequence, optional
Whether to return a recarray or a mrecarray (`asrecarray=True`) or
a plain ndarray or masked array with flexible dtype. The default
is False.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> a = np.array([(1, (2, 3.0)), (4, (5, 6.0))],
... dtype=[('a', np.int64), ('b', [('ba', np.double), ('bb', np.int64)])])
>>> rfn.drop_fields(a, 'a')
array([((2., 3),), ((5., 6),)],
dtype=[('b', [('ba', '<f8'), ('bb', '<i8')])])
>>> rfn.drop_fields(a, 'ba')
array([(1, (3,)), (4, (6,))], dtype=[('a', '<i8'), ('b', [('bb', '<i8')])])
>>> rfn.drop_fields(a, ['ba', 'bb'])
array([(1,), (4,)], dtype=[('a', '<i8')])
"""
if _is_string_like(drop_names):
drop_names = [drop_names]
else:
drop_names = set(drop_names)
def _drop_descr(ndtype, drop_names):
names = ndtype.names
newdtype = []
for name in names:
current = ndtype[name]
if name in drop_names:
continue
if current.names is not None:
descr = _drop_descr(current, drop_names)
if descr:
newdtype.append((name, descr))
else:
newdtype.append((name, current))
return newdtype
newdtype = _drop_descr(base.dtype, drop_names)
output = np.empty(base.shape, dtype=newdtype)
output = recursive_fill_fields(base, output)
return _fix_output(output, usemask=usemask, asrecarray=asrecarray)
def _keep_fields(base, keep_names, usemask=True, asrecarray=False):
"""
Return a new array keeping only the fields in `keep_names`,
and preserving the order of those fields.
Parameters
----------
base : array
Input array
keep_names : string or sequence
String or sequence of strings corresponding to the names of the
fields to keep. Order of the names will be preserved.
usemask : {False, True}, optional
Whether to return a masked array or not.
asrecarray : string or sequence, optional
Whether to return a recarray or a mrecarray (`asrecarray=True`) or
a plain ndarray or masked array with flexible dtype. The default
is False.
"""
newdtype = [(n, base.dtype[n]) for n in keep_names]
output = np.empty(base.shape, dtype=newdtype)
output = recursive_fill_fields(base, output)
return _fix_output(output, usemask=usemask, asrecarray=asrecarray)
def _rec_drop_fields_dispatcher(base, drop_names):
return (base,)
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@array_function_dispatch(_rec_drop_fields_dispatcher)
def rec_drop_fields(base, drop_names):
"""
Returns a new numpy.recarray with fields in `drop_names` dropped.
"""
return drop_fields(base, drop_names, usemask=False, asrecarray=True)
def _rename_fields_dispatcher(base, namemapper):
return (base,)
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@array_function_dispatch(_rename_fields_dispatcher)
def rename_fields(base, namemapper):
"""
Rename the fields from a flexible-datatype ndarray or recarray.
Nested fields are supported.
Parameters
----------
base : ndarray
Input array whose fields must be modified.
namemapper : dictionary
Dictionary mapping old field names to their new version.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> a = np.array([(1, (2, [3.0, 30.])), (4, (5, [6.0, 60.]))],
... dtype=[('a', int),('b', [('ba', float), ('bb', (float, 2))])])
>>> rfn.rename_fields(a, {'a':'A', 'bb':'BB'})
array([(1, (2., [ 3., 30.])), (4, (5., [ 6., 60.]))],
dtype=[('A', '<i8'), ('b', [('ba', '<f8'), ('BB', '<f8', (2,))])])
"""
def _recursive_rename_fields(ndtype, namemapper):
newdtype = []
for name in ndtype.names:
newname = namemapper.get(name, name)
current = ndtype[name]
if current.names is not None:
newdtype.append(
(newname, _recursive_rename_fields(current, namemapper))
)
else:
newdtype.append((newname, current))
return newdtype
newdtype = _recursive_rename_fields(base.dtype, namemapper)
return base.view(newdtype)
def _append_fields_dispatcher(base, names, data, dtypes=None,
fill_value=None, usemask=None, asrecarray=None):
yield base
yield from data
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@array_function_dispatch(_append_fields_dispatcher)
def append_fields(base, names, data, dtypes=None,
fill_value=-1, usemask=True, asrecarray=False):
"""
Add new fields to an existing array.
The names of the fields are given with the `names` arguments,
the corresponding values with the `data` arguments.
If a single field is appended, `names`, `data` and `dtypes` do not have
to be lists but just values.
Parameters
----------
base : array
Input array to extend.
names : string, sequence
String or sequence of strings corresponding to the names
of the new fields.
data : array or sequence of arrays
Array or sequence of arrays storing the fields to add to the base.
dtypes : sequence of datatypes, optional
Datatype or sequence of datatypes.
If None, the datatypes are estimated from the `data`.
fill_value : {float}, optional
Filling value used to pad missing data on the shorter arrays.
usemask : {False, True}, optional
Whether to return a masked array or not.
asrecarray : {False, True}, optional
Whether to return a recarray (MaskedRecords) or not.
"""
# Check the names
if isinstance(names, (tuple, list)):
if len(names) != len(data):
msg = "The number of arrays does not match the number of names"
raise ValueError(msg)
elif isinstance(names, str):
names = [names, ]
data = [data, ]
#
if dtypes is None:
data = [np.array(a, copy=None, subok=True) for a in data]
data = [a.view([(name, a.dtype)]) for (name, a) in zip(names, data)]
else:
if not isinstance(dtypes, (tuple, list)):
dtypes = [dtypes, ]
if len(data) != len(dtypes):
if len(dtypes) == 1:
dtypes = dtypes * len(data)
else:
msg = "The dtypes argument must be None, a dtype, or a list."
raise ValueError(msg)
data = [np.array(a, copy=None, subok=True, dtype=d).view([(n, d)])
for (a, n, d) in zip(data, names, dtypes)]
#
base = merge_arrays(base, usemask=usemask, fill_value=fill_value)
if len(data) > 1:
data = merge_arrays(data, flatten=True, usemask=usemask,
fill_value=fill_value)
else:
data = data.pop()
#
output = ma.masked_all(
max(len(base), len(data)),
dtype=_get_fieldspec(base.dtype) + _get_fieldspec(data.dtype))
output = recursive_fill_fields(base, output)
output = recursive_fill_fields(data, output)
#
return _fix_output(output, usemask=usemask, asrecarray=asrecarray)
def _rec_append_fields_dispatcher(base, names, data, dtypes=None):
yield base
yield from data
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@array_function_dispatch(_rec_append_fields_dispatcher)
def rec_append_fields(base, names, data, dtypes=None):
"""
Add new fields to an existing array.
The names of the fields are given with the `names` arguments,
the corresponding values with the `data` arguments.
If a single field is appended, `names`, `data` and `dtypes` do not have
to be lists but just values.
Parameters
----------
base : array
Input array to extend.
names : string, sequence
String or sequence of strings corresponding to the names
of the new fields.
data : array or sequence of arrays
Array or sequence of arrays storing the fields to add to the base.
dtypes : sequence of datatypes, optional
Datatype or sequence of datatypes.
If None, the datatypes are estimated from the `data`.
See Also
--------
append_fields
Returns
-------
appended_array : np.recarray
"""
return append_fields(base, names, data=data, dtypes=dtypes,
asrecarray=True, usemask=False)
def _repack_fields_dispatcher(a, align=None, recurse=None):
return (a,)
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@array_function_dispatch(_repack_fields_dispatcher)
def repack_fields(a, align=False, recurse=False):
"""
Re-pack the fields of a structured array or dtype in memory.
The memory layout of structured datatypes allows fields at arbitrary
byte offsets. This means the fields can be separated by padding bytes,
their offsets can be non-monotonically increasing, and they can overlap.
This method removes any overlaps and reorders the fields in memory so they
have increasing byte offsets, and adds or removes padding bytes depending
on the `align` option, which behaves like the `align` option to
`numpy.dtype`.
If `align=False`, this method produces a "packed" memory layout in which
each field starts at the byte the previous field ended, and any padding
bytes are removed.
If `align=True`, this methods produces an "aligned" memory layout in which
each field's offset is a multiple of its alignment, and the total itemsize
is a multiple of the largest alignment, by adding padding bytes as needed.
Parameters
----------
a : ndarray or dtype
array or dtype for which to repack the fields.
align : boolean
If true, use an "aligned" memory layout, otherwise use a "packed" layout.
recurse : boolean
If True, also repack nested structures.
Returns
-------
repacked : ndarray or dtype
Copy of `a` with fields repacked, or `a` itself if no repacking was
needed.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> def print_offsets(d):
... print("offsets:", [d.fields[name][1] for name in d.names])
... print("itemsize:", d.itemsize)
...
>>> dt = np.dtype('u1, <i8, <f8', align=True)
>>> dt
dtype({'names': ['f0', 'f1', 'f2'], 'formats': ['u1', '<i8', '<f8'], \
'offsets': [0, 8, 16], 'itemsize': 24}, align=True)
>>> print_offsets(dt)
offsets: [0, 8, 16]
itemsize: 24
>>> packed_dt = rfn.repack_fields(dt)
>>> packed_dt
dtype([('f0', 'u1'), ('f1', '<i8'), ('f2', '<f8')])
>>> print_offsets(packed_dt)
offsets: [0, 1, 9]
itemsize: 17
"""
if not isinstance(a, np.dtype):
dt = repack_fields(a.dtype, align=align, recurse=recurse)
return a.astype(dt, copy=False)
if a.names is None:
return a
fieldinfo = []
for name in a.names:
tup = a.fields[name]
if recurse:
fmt = repack_fields(tup[0], align=align, recurse=True)
else:
fmt = tup[0]
if len(tup) == 3:
name = (tup[2], name)
fieldinfo.append((name, fmt))
dt = np.dtype(fieldinfo, align=align)
return np.dtype((a.type, dt))
def _get_fields_and_offsets(dt, offset=0):
"""
Returns a flat list of (dtype, count, offset) tuples of all the
scalar fields in the dtype "dt", including nested fields, in left
to right order.
"""
# counts up elements in subarrays, including nested subarrays, and returns
# base dtype and count
def count_elem(dt):
count = 1
while dt.shape != ():
for size in dt.shape:
count *= size
dt = dt.base
return dt, count
fields = []
for name in dt.names:
field = dt.fields[name]
f_dt, f_offset = field[0], field[1]
f_dt, n = count_elem(f_dt)
if f_dt.names is None:
fields.append((np.dtype((f_dt, (n,))), n, f_offset + offset))
else:
subfields = _get_fields_and_offsets(f_dt, f_offset + offset)
size = f_dt.itemsize
for i in range(n):
if i == 0:
# optimization: avoid list comprehension if no subarray
fields.extend(subfields)
else:
fields.extend([(d, c, o + i*size) for d, c, o in subfields])
return fields
def _common_stride(offsets, counts, itemsize):
"""
Returns the stride between the fields, or None if the stride is not
constant. The values in "counts" designate the lengths of
subarrays. Subarrays are treated as many contiguous fields, with
always positive stride.
"""
if len(offsets) <= 1:
return itemsize
negative = offsets[1] < offsets[0] # negative stride
if negative:
# reverse, so offsets will be ascending
it = zip(reversed(offsets), reversed(counts))
else:
it = zip(offsets, counts)
prev_offset = None
stride = None
for offset, count in it:
if count != 1: # subarray: always c-contiguous
if negative:
return None # subarrays can never have a negative stride
if stride is None:
stride = itemsize
if stride != itemsize:
return None
end_offset = offset + (count - 1) * itemsize
else:
end_offset = offset
if prev_offset is not None:
new_stride = offset - prev_offset
if stride is None:
stride = new_stride
if stride != new_stride:
return None
prev_offset = end_offset
if negative:
return -stride
return stride
def _structured_to_unstructured_dispatcher(arr, dtype=None, copy=None,
casting=None):
return (arr,)
[文档]
@array_function_dispatch(_structured_to_unstructured_dispatcher)
def structured_to_unstructured(arr, dtype=None, copy=False, casting='unsafe'):
"""
Converts an n-D structured array into an (n+1)-D unstructured array.
The new array will have a new last dimension equal in size to the
number of field-elements of the input array. If not supplied, the output
datatype is determined from the numpy type promotion rules applied to all
the field datatypes.
Nested fields, as well as each element of any subarray fields, all count
as a single field-elements.
Parameters
----------
arr : ndarray
Structured array or dtype to convert. Cannot contain object datatype.
dtype : dtype, optional
The dtype of the output unstructured array.
copy : bool, optional
If true, always return a copy. If false, a view is returned if
possible, such as when the `dtype` and strides of the fields are
suitable and the array subtype is one of `numpy.ndarray`,
`numpy.recarray` or `numpy.memmap`.
.. versionchanged:: 1.25.0
A view can now be returned if the fields are separated by a
uniform stride.
casting : {'no', 'equiv', 'safe', 'same_kind', 'unsafe'}, optional
See casting argument of `numpy.ndarray.astype`. Controls what kind of
data casting may occur.
Returns
-------
unstructured : ndarray
Unstructured array with one more dimension.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> a = np.zeros(4, dtype=[('a', 'i4'), ('b', 'f4,u2'), ('c', 'f4', 2)])
>>> a
array([(0, (0., 0), [0., 0.]), (0, (0., 0), [0., 0.]),
(0, (0., 0), [0., 0.]), (0, (0., 0), [0., 0.])],
dtype=[('a', '<i4'), ('b', [('f0', '<f4'), ('f1', '<u2')]), ('c', '<f4', (2,))])
>>> rfn.structured_to_unstructured(a)
array([[0., 0., 0., 0., 0.],
[0., 0., 0., 0., 0.],
[0., 0., 0., 0., 0.],
[0., 0., 0., 0., 0.]])
>>> b = np.array([(1, 2, 5), (4, 5, 7), (7, 8 ,11), (10, 11, 12)],
... dtype=[('x', 'i4'), ('y', 'f4'), ('z', 'f8')])
>>> np.mean(rfn.structured_to_unstructured(b[['x', 'z']]), axis=-1)
array([ 3. , 5.5, 9. , 11. ])
"""
if arr.dtype.names is None:
raise ValueError('arr must be a structured array')
fields = _get_fields_and_offsets(arr.dtype)
n_fields = len(fields)
if n_fields == 0 and dtype is None:
raise ValueError("arr has no fields. Unable to guess dtype")
elif n_fields == 0:
# too many bugs elsewhere for this to work now
raise NotImplementedError("arr with no fields is not supported")
dts, counts, offsets = zip(*fields)
names = ['f{}'.format(n) for n in range(n_fields)]
if dtype is None:
out_dtype = np.result_type(*[dt.base for dt in dts])
else:
out_dtype = np.dtype(dtype)
# Use a series of views and casts to convert to an unstructured array:
# first view using flattened fields (doesn't work for object arrays)
# Note: dts may include a shape for subarrays
flattened_fields = np.dtype({'names': names,
'formats': dts,
'offsets': offsets,
'itemsize': arr.dtype.itemsize})
arr = arr.view(flattened_fields)
# we only allow a few types to be unstructured by manipulating the
# strides, because we know it won't work with, for example, np.matrix nor
# np.ma.MaskedArray.
can_view = type(arr) in (np.ndarray, np.recarray, np.memmap)
if (not copy) and can_view and all(dt.base == out_dtype for dt in dts):
# all elements have the right dtype already; if they have a common
# stride, we can just return a view
common_stride = _common_stride(offsets, counts, out_dtype.itemsize)
if common_stride is not None:
wrap = arr.__array_wrap__
new_shape = arr.shape + (sum(counts), out_dtype.itemsize)
new_strides = arr.strides + (abs(common_stride), 1)
arr = arr[..., np.newaxis].view(np.uint8) # view as bytes
arr = arr[..., min(offsets):] # remove the leading unused data
arr = np.lib.stride_tricks.as_strided(arr,
new_shape,
new_strides,
subok=True)
# cast and drop the last dimension again
arr = arr.view(out_dtype)[..., 0]
if common_stride < 0:
arr = arr[..., ::-1] # reverse, if the stride was negative
if type(arr) is not type(wrap.__self__):
# Some types (e.g. recarray) turn into an ndarray along the
# way, so we have to wrap it again in order to match the
# behavior with copy=True.
arr = wrap(arr)
return arr
# next cast to a packed format with all fields converted to new dtype
packed_fields = np.dtype({'names': names,
'formats': [(out_dtype, dt.shape) for dt in dts]})
arr = arr.astype(packed_fields, copy=copy, casting=casting)
# finally is it safe to view the packed fields as the unstructured type
return arr.view((out_dtype, (sum(counts),)))
def _unstructured_to_structured_dispatcher(arr, dtype=None, names=None,
align=None, copy=None, casting=None):
return (arr,)
[文档]
@array_function_dispatch(_unstructured_to_structured_dispatcher)
def unstructured_to_structured(arr, dtype=None, names=None, align=False,
copy=False, casting='unsafe'):
"""
Converts an n-D unstructured array into an (n-1)-D structured array.
The last dimension of the input array is converted into a structure, with
number of field-elements equal to the size of the last dimension of the
input array. By default all output fields have the input array's dtype, but
an output structured dtype with an equal number of fields-elements can be
supplied instead.
Nested fields, as well as each element of any subarray fields, all count
towards the number of field-elements.
Parameters
----------
arr : ndarray
Unstructured array or dtype to convert.
dtype : dtype, optional
The structured dtype of the output array
names : list of strings, optional
If dtype is not supplied, this specifies the field names for the output
dtype, in order. The field dtypes will be the same as the input array.
align : boolean, optional
Whether to create an aligned memory layout.
copy : bool, optional
See copy argument to `numpy.ndarray.astype`. If true, always return a
copy. If false, and `dtype` requirements are satisfied, a view is
returned.
casting : {'no', 'equiv', 'safe', 'same_kind', 'unsafe'}, optional
See casting argument of `numpy.ndarray.astype`. Controls what kind of
data casting may occur.
Returns
-------
structured : ndarray
Structured array with fewer dimensions.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> dt = np.dtype([('a', 'i4'), ('b', 'f4,u2'), ('c', 'f4', 2)])
>>> a = np.arange(20).reshape((4,5))
>>> a
array([[ 0, 1, 2, 3, 4],
[ 5, 6, 7, 8, 9],
[10, 11, 12, 13, 14],
[15, 16, 17, 18, 19]])
>>> rfn.unstructured_to_structured(a, dt)
array([( 0, ( 1., 2), [ 3., 4.]), ( 5, ( 6., 7), [ 8., 9.]),
(10, (11., 12), [13., 14.]), (15, (16., 17), [18., 19.])],
dtype=[('a', '<i4'), ('b', [('f0', '<f4'), ('f1', '<u2')]), ('c', '<f4', (2,))])
"""
if arr.shape == ():
raise ValueError('arr must have at least one dimension')
n_elem = arr.shape[-1]
if n_elem == 0:
# too many bugs elsewhere for this to work now
raise NotImplementedError("last axis with size 0 is not supported")
if dtype is None:
if names is None:
names = ['f{}'.format(n) for n in range(n_elem)]
out_dtype = np.dtype([(n, arr.dtype) for n in names], align=align)
fields = _get_fields_and_offsets(out_dtype)
dts, counts, offsets = zip(*fields)
else:
if names is not None:
raise ValueError("don't supply both dtype and names")
# if dtype is the args of np.dtype, construct it
dtype = np.dtype(dtype)
# sanity check of the input dtype
fields = _get_fields_and_offsets(dtype)
if len(fields) == 0:
dts, counts, offsets = [], [], []
else:
dts, counts, offsets = zip(*fields)
if n_elem != sum(counts):
raise ValueError('The length of the last dimension of arr must '
'be equal to the number of fields in dtype')
out_dtype = dtype
if align and not out_dtype.isalignedstruct:
raise ValueError("align was True but dtype is not aligned")
names = ['f{}'.format(n) for n in range(len(fields))]
# Use a series of views and casts to convert to a structured array:
# first view as a packed structured array of one dtype
packed_fields = np.dtype({'names': names,
'formats': [(arr.dtype, dt.shape) for dt in dts]})
arr = np.ascontiguousarray(arr).view(packed_fields)
# next cast to an unpacked but flattened format with varied dtypes
flattened_fields = np.dtype({'names': names,
'formats': dts,
'offsets': offsets,
'itemsize': out_dtype.itemsize})
arr = arr.astype(flattened_fields, copy=copy, casting=casting)
# finally view as the final nested dtype and remove the last axis
return arr.view(out_dtype)[..., 0]
def _apply_along_fields_dispatcher(func, arr):
return (arr,)
[文档]
@array_function_dispatch(_apply_along_fields_dispatcher)
def apply_along_fields(func, arr):
"""
Apply function 'func' as a reduction across fields of a structured array.
This is similar to `numpy.apply_along_axis`, but treats the fields of a
structured array as an extra axis. The fields are all first cast to a
common type following the type-promotion rules from `numpy.result_type`
applied to the field's dtypes.
Parameters
----------
func : function
Function to apply on the "field" dimension. This function must
support an `axis` argument, like `numpy.mean`, `numpy.sum`, etc.
arr : ndarray
Structured array for which to apply func.
Returns
-------
out : ndarray
Result of the recution operation
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> b = np.array([(1, 2, 5), (4, 5, 7), (7, 8 ,11), (10, 11, 12)],
... dtype=[('x', 'i4'), ('y', 'f4'), ('z', 'f8')])
>>> rfn.apply_along_fields(np.mean, b)
array([ 2.66666667, 5.33333333, 8.66666667, 11. ])
>>> rfn.apply_along_fields(np.mean, b[['x', 'z']])
array([ 3. , 5.5, 9. , 11. ])
"""
if arr.dtype.names is None:
raise ValueError('arr must be a structured array')
uarr = structured_to_unstructured(arr)
return func(uarr, axis=-1)
# works and avoids axis requirement, but very, very slow:
#return np.apply_along_axis(func, -1, uarr)
def _assign_fields_by_name_dispatcher(dst, src, zero_unassigned=None):
return dst, src
[文档]
@array_function_dispatch(_assign_fields_by_name_dispatcher)
def assign_fields_by_name(dst, src, zero_unassigned=True):
"""
Assigns values from one structured array to another by field name.
Normally in numpy >= 1.14, assignment of one structured array to another
copies fields "by position", meaning that the first field from the src is
copied to the first field of the dst, and so on, regardless of field name.
This function instead copies "by field name", such that fields in the dst
are assigned from the identically named field in the src. This applies
recursively for nested structures. This is how structure assignment worked
in numpy >= 1.6 to <= 1.13.
Parameters
----------
dst : ndarray
src : ndarray
The source and destination arrays during assignment.
zero_unassigned : bool, optional
If True, fields in the dst for which there was no matching
field in the src are filled with the value 0 (zero). This
was the behavior of numpy <= 1.13. If False, those fields
are not modified.
"""
if dst.dtype.names is None:
dst[...] = src
return
for name in dst.dtype.names:
if name not in src.dtype.names:
if zero_unassigned:
dst[name] = 0
else:
assign_fields_by_name(dst[name], src[name],
zero_unassigned)
def _require_fields_dispatcher(array, required_dtype):
return (array,)
[文档]
@array_function_dispatch(_require_fields_dispatcher)
def require_fields(array, required_dtype):
"""
Casts a structured array to a new dtype using assignment by field-name.
This function assigns from the old to the new array by name, so the
value of a field in the output array is the value of the field with the
same name in the source array. This has the effect of creating a new
ndarray containing only the fields "required" by the required_dtype.
If a field name in the required_dtype does not exist in the
input array, that field is created and set to 0 in the output array.
Parameters
----------
a : ndarray
array to cast
required_dtype : dtype
datatype for output array
Returns
-------
out : ndarray
array with the new dtype, with field values copied from the fields in
the input array with the same name
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> a = np.ones(4, dtype=[('a', 'i4'), ('b', 'f8'), ('c', 'u1')])
>>> rfn.require_fields(a, [('b', 'f4'), ('c', 'u1')])
array([(1., 1), (1., 1), (1., 1), (1., 1)],
dtype=[('b', '<f4'), ('c', 'u1')])
>>> rfn.require_fields(a, [('b', 'f4'), ('newf', 'u1')])
array([(1., 0), (1., 0), (1., 0), (1., 0)],
dtype=[('b', '<f4'), ('newf', 'u1')])
"""
out = np.empty(array.shape, dtype=required_dtype)
assign_fields_by_name(out, array)
return out
def _stack_arrays_dispatcher(arrays, defaults=None, usemask=None,
asrecarray=None, autoconvert=None):
return arrays
[文档]
@array_function_dispatch(_stack_arrays_dispatcher)
def stack_arrays(arrays, defaults=None, usemask=True, asrecarray=False,
autoconvert=False):
"""
Superposes arrays fields by fields
Parameters
----------
arrays : array or sequence
Sequence of input arrays.
defaults : dictionary, optional
Dictionary mapping field names to the corresponding default values.
usemask : {True, False}, optional
Whether to return a MaskedArray (or MaskedRecords is
`asrecarray==True`) or a ndarray.
asrecarray : {False, True}, optional
Whether to return a recarray (or MaskedRecords if `usemask==True`)
or just a flexible-type ndarray.
autoconvert : {False, True}, optional
Whether automatically cast the type of the field to the maximum.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> x = np.array([1, 2,])
>>> rfn.stack_arrays(x) is x
True
>>> z = np.array([('A', 1), ('B', 2)], dtype=[('A', '|S3'), ('B', float)])
>>> zz = np.array([('a', 10., 100.), ('b', 20., 200.), ('c', 30., 300.)],
... dtype=[('A', '|S3'), ('B', np.double), ('C', np.double)])
>>> test = rfn.stack_arrays((z,zz))
>>> test
masked_array(data=[(b'A', 1.0, --), (b'B', 2.0, --), (b'a', 10.0, 100.0),
(b'b', 20.0, 200.0), (b'c', 30.0, 300.0)],
mask=[(False, False, True), (False, False, True),
(False, False, False), (False, False, False),
(False, False, False)],
fill_value=(b'N/A', 1e+20, 1e+20),
dtype=[('A', 'S3'), ('B', '<f8'), ('C', '<f8')])
"""
if isinstance(arrays, ndarray):
return arrays
elif len(arrays) == 1:
return arrays[0]
seqarrays = [np.asanyarray(a).ravel() for a in arrays]
nrecords = [len(a) for a in seqarrays]
ndtype = [a.dtype for a in seqarrays]
fldnames = [d.names for d in ndtype]
#
dtype_l = ndtype[0]
newdescr = _get_fieldspec(dtype_l)
names = [n for n, d in newdescr]
for dtype_n in ndtype[1:]:
for fname, fdtype in _get_fieldspec(dtype_n):
if fname not in names:
newdescr.append((fname, fdtype))
names.append(fname)
else:
nameidx = names.index(fname)
_, cdtype = newdescr[nameidx]
if autoconvert:
newdescr[nameidx] = (fname, max(fdtype, cdtype))
elif fdtype != cdtype:
raise TypeError("Incompatible type '%s' <> '%s'" %
(cdtype, fdtype))
# Only one field: use concatenate
if len(newdescr) == 1:
output = ma.concatenate(seqarrays)
else:
#
output = ma.masked_all((np.sum(nrecords),), newdescr)
offset = np.cumsum(np.r_[0, nrecords])
seen = []
for (a, n, i, j) in zip(seqarrays, fldnames, offset[:-1], offset[1:]):
names = a.dtype.names
if names is None:
output['f%i' % len(seen)][i:j] = a
else:
for name in n:
output[name][i:j] = a[name]
if name not in seen:
seen.append(name)
#
return _fix_output(_fix_defaults(output, defaults),
usemask=usemask, asrecarray=asrecarray)
def _find_duplicates_dispatcher(
a, key=None, ignoremask=None, return_index=None):
return (a,)
[文档]
@array_function_dispatch(_find_duplicates_dispatcher)
def find_duplicates(a, key=None, ignoremask=True, return_index=False):
"""
Find the duplicates in a structured array along a given key
Parameters
----------
a : array-like
Input array
key : {string, None}, optional
Name of the fields along which to check the duplicates.
If None, the search is performed by records
ignoremask : {True, False}, optional
Whether masked data should be discarded or considered as duplicates.
return_index : {False, True}, optional
Whether to return the indices of the duplicated values.
Examples
--------
>>> from numpy.lib import recfunctions as rfn
>>> ndtype = [('a', int)]
>>> a = np.ma.array([1, 1, 1, 2, 2, 3, 3],
... mask=[0, 0, 1, 0, 0, 0, 1]).view(ndtype)
>>> rfn.find_duplicates(a, ignoremask=True, return_index=True)
(masked_array(data=[(1,), (1,), (2,), (2,)],
mask=[(False,), (False,), (False,), (False,)],
fill_value=(999999,),
dtype=[('a', '<i8')]), array([0, 1, 3, 4]))
"""
a = np.asanyarray(a).ravel()
# Get a dictionary of fields
fields = get_fieldstructure(a.dtype)
# Get the sorting data (by selecting the corresponding field)
base = a
if key:
for f in fields[key]:
base = base[f]
base = base[key]
# Get the sorting indices and the sorted data
sortidx = base.argsort()
sortedbase = base[sortidx]
sorteddata = sortedbase.filled()
# Compare the sorting data
flag = (sorteddata[:-1] == sorteddata[1:])
# If masked data must be ignored, set the flag to false where needed
if ignoremask:
sortedmask = sortedbase.recordmask
flag[sortedmask[1:]] = False
flag = np.concatenate(([False], flag))
# We need to take the point on the left as well (else we're missing it)
flag[:-1] = flag[:-1] + flag[1:]
duplicates = a[sortidx][flag]
if return_index:
return (duplicates, sortidx[flag])
else:
return duplicates
def _join_by_dispatcher(
key, r1, r2, jointype=None, r1postfix=None, r2postfix=None,
defaults=None, usemask=None, asrecarray=None):
return (r1, r2)
[文档]
@array_function_dispatch(_join_by_dispatcher)
def join_by(key, r1, r2, jointype='inner', r1postfix='1', r2postfix='2',
defaults=None, usemask=True, asrecarray=False):
"""
Join arrays `r1` and `r2` on key `key`.
The key should be either a string or a sequence of string corresponding
to the fields used to join the array. An exception is raised if the
`key` field cannot be found in the two input arrays. Neither `r1` nor
`r2` should have any duplicates along `key`: the presence of duplicates
will make the output quite unreliable. Note that duplicates are not
looked for by the algorithm.
Parameters
----------
key : {string, sequence}
A string or a sequence of strings corresponding to the fields used
for comparison.
r1, r2 : arrays
Structured arrays.
jointype : {'inner', 'outer', 'leftouter'}, optional
If 'inner', returns the elements common to both r1 and r2.
If 'outer', returns the common elements as well as the elements of
r1 not in r2 and the elements of not in r2.
If 'leftouter', returns the common elements and the elements of r1
not in r2.
r1postfix : string, optional
String appended to the names of the fields of r1 that are present
in r2 but absent of the key.
r2postfix : string, optional
String appended to the names of the fields of r2 that are present
in r1 but absent of the key.
defaults : {dictionary}, optional
Dictionary mapping field names to the corresponding default values.
usemask : {True, False}, optional
Whether to return a MaskedArray (or MaskedRecords is
`asrecarray==True`) or a ndarray.
asrecarray : {False, True}, optional
Whether to return a recarray (or MaskedRecords if `usemask==True`)
or just a flexible-type ndarray.
Notes
-----
* The output is sorted along the key.
* A temporary array is formed by dropping the fields not in the key for
the two arrays and concatenating the result. This array is then
sorted, and the common entries selected. The output is constructed by
filling the fields with the selected entries. Matching is not
preserved if there are some duplicates...
"""
# Check jointype
if jointype not in ('inner', 'outer', 'leftouter'):
raise ValueError(
"The 'jointype' argument should be in 'inner', "
"'outer' or 'leftouter' (got '%s' instead)" % jointype
)
# If we have a single key, put it in a tuple
if isinstance(key, str):
key = (key,)
# Check the keys
if len(set(key)) != len(key):
dup = next(x for n,x in enumerate(key) if x in key[n+1:])
raise ValueError("duplicate join key %r" % dup)
for name in key:
if name not in r1.dtype.names:
raise ValueError('r1 does not have key field %r' % name)
if name not in r2.dtype.names:
raise ValueError('r2 does not have key field %r' % name)
# Make sure we work with ravelled arrays
r1 = r1.ravel()
r2 = r2.ravel()
# Fixme: nb2 below is never used. Commenting out for pyflakes.
# (nb1, nb2) = (len(r1), len(r2))
nb1 = len(r1)
(r1names, r2names) = (r1.dtype.names, r2.dtype.names)
# Check the names for collision
collisions = (set(r1names) & set(r2names)) - set(key)
if collisions and not (r1postfix or r2postfix):
msg = "r1 and r2 contain common names, r1postfix and r2postfix "
msg += "can't both be empty"
raise ValueError(msg)
# Make temporary arrays of just the keys
# (use order of keys in `r1` for back-compatibility)
key1 = [ n for n in r1names if n in key ]
r1k = _keep_fields(r1, key1)
r2k = _keep_fields(r2, key1)
# Concatenate the two arrays for comparison
aux = ma.concatenate((r1k, r2k))
idx_sort = aux.argsort(order=key)
aux = aux[idx_sort]
#
# Get the common keys
flag_in = ma.concatenate(([False], aux[1:] == aux[:-1]))
flag_in[:-1] = flag_in[1:] + flag_in[:-1]
idx_in = idx_sort[flag_in]
idx_1 = idx_in[(idx_in < nb1)]
idx_2 = idx_in[(idx_in >= nb1)] - nb1
(r1cmn, r2cmn) = (len(idx_1), len(idx_2))
if jointype == 'inner':
(r1spc, r2spc) = (0, 0)
elif jointype == 'outer':
idx_out = idx_sort[~flag_in]
idx_1 = np.concatenate((idx_1, idx_out[(idx_out < nb1)]))
idx_2 = np.concatenate((idx_2, idx_out[(idx_out >= nb1)] - nb1))
(r1spc, r2spc) = (len(idx_1) - r1cmn, len(idx_2) - r2cmn)
elif jointype == 'leftouter':
idx_out = idx_sort[~flag_in]
idx_1 = np.concatenate((idx_1, idx_out[(idx_out < nb1)]))
(r1spc, r2spc) = (len(idx_1) - r1cmn, 0)
# Select the entries from each input
(s1, s2) = (r1[idx_1], r2[idx_2])
#
# Build the new description of the output array .......
# Start with the key fields
ndtype = _get_fieldspec(r1k.dtype)
# Add the fields from r1
for fname, fdtype in _get_fieldspec(r1.dtype):
if fname not in key:
ndtype.append((fname, fdtype))
# Add the fields from r2
for fname, fdtype in _get_fieldspec(r2.dtype):
# Have we seen the current name already ?
# we need to rebuild this list every time
names = list(name for name, dtype in ndtype)
try:
nameidx = names.index(fname)
except ValueError:
#... we haven't: just add the description to the current list
ndtype.append((fname, fdtype))
else:
# collision
_, cdtype = ndtype[nameidx]
if fname in key:
# The current field is part of the key: take the largest dtype
ndtype[nameidx] = (fname, max(fdtype, cdtype))
else:
# The current field is not part of the key: add the suffixes,
# and place the new field adjacent to the old one
ndtype[nameidx:nameidx + 1] = [
(fname + r1postfix, cdtype),
(fname + r2postfix, fdtype)
]
# Rebuild a dtype from the new fields
ndtype = np.dtype(ndtype)
# Find the largest nb of common fields :
# r1cmn and r2cmn should be equal, but...
cmn = max(r1cmn, r2cmn)
# Construct an empty array
output = ma.masked_all((cmn + r1spc + r2spc,), dtype=ndtype)
names = output.dtype.names
for f in r1names:
selected = s1[f]
if f not in names or (f in r2names and not r2postfix and f not in key):
f += r1postfix
current = output[f]
current[:r1cmn] = selected[:r1cmn]
if jointype in ('outer', 'leftouter'):
current[cmn:cmn + r1spc] = selected[r1cmn:]
for f in r2names:
selected = s2[f]
if f not in names or (f in r1names and not r1postfix and f not in key):
f += r2postfix
current = output[f]
current[:r2cmn] = selected[:r2cmn]
if (jointype == 'outer') and r2spc:
current[-r2spc:] = selected[r2cmn:]
# Sort and finalize the output
output.sort(order=key)
kwargs = dict(usemask=usemask, asrecarray=asrecarray)
return _fix_output(_fix_defaults(output, defaults), **kwargs)
def _rec_join_dispatcher(
key, r1, r2, jointype=None, r1postfix=None, r2postfix=None,
defaults=None):
return (r1, r2)
[文档]
@array_function_dispatch(_rec_join_dispatcher)
def rec_join(key, r1, r2, jointype='inner', r1postfix='1', r2postfix='2',
defaults=None):
"""
Join arrays `r1` and `r2` on keys.
Alternative to join_by, that always returns a np.recarray.
See Also
--------
join_by : equivalent function
"""
kwargs = dict(jointype=jointype, r1postfix=r1postfix, r2postfix=r2postfix,
defaults=defaults, usemask=False, asrecarray=True)
return join_by(key, r1, r2, **kwargs)
