Python numpy 模块，masked() 实例源码
我们从Python开源项目中，提取了以下50个代码示例，用于说明如何使用numpy.masked()。
def get_masked_subclass(*arrays):
"""
Return the youngest subclass of MaskedArray from a list of (masked) arrays.
In case of siblings, the first listed takes over.
"""
if len(arrays) == 1:
arr = arrays[0]
if isinstance(arr, MaskedArray):
rcls = type(arr)
else:
rcls = MaskedArray
else:
arrcls = [type(a) for a in arrays]
rcls = arrcls[0]
if not issubclass(rcls, MaskedArray):
rcls = MaskedArray
for cls in arrcls[1:]:
if issubclass(cls, rcls):
rcls = cls
# Don't return MaskedConstant as result: revert to MaskedArray
if rcls.__name__ == 'MaskedConstant':
return MaskedArray
return rcls
def outer(self, a, b):
"""
Return the function applied to the outer product of a and b.
"""
(da, db) = (getdata(a), getdata(b))
d = self.f.outer(da, db)
ma = getmask(a)
mb = getmask(b)
if ma is nomask and mb is nomask:
m = nomask
else:
ma = getmaskarray(a)
mb = getmaskarray(b)
m = umath.logical_or.outer(ma, mb)
if (not m.ndim) and m:
return masked
if m is not nomask:
np.copyto(d, da, where=m)
if not d.shape:
return d
masked_d = d.view(get_masked_subclass(a, b))
masked_d._mask = m
return masked_d
def unshare_mask(self):
"""
Copy the mask and set the sharedmask flag to False.
Whether the mask is shared between masked arrays can be seen from
the `sharedmask` property. `unshare_mask` ensures the mask is not shared.
A copy of the mask is only made if it was shared.
See Also
--------
sharedmask
"""
if self._sharedmask:
self._mask = self._mask.copy()
self._sharedmask = False
return self
def resize(self, newshape, refcheck=True, order=False):
"""
.. warning::
This method does nothing, except raise a ValueError exception. A
masked array does not own its data and therefore cannot safely be
resized in place. Use the `numpy.ma.resize` function instead.
This method is difficult to implement safely and may be deprecated in
future releases of NumPy.
"""
# Note : the 'order' keyword looks broken, let's just drop it
errmsg = "A masked array does not own its data "\
"and therefore cannot be resized.\n" \
"Use the numpy.ma.resize function instead."
raise ValueError(errmsg)
def round(self, decimals=0, out=None):
"""
Return an array rounded a to the given number of decimals.
Refer to `numpy.around` for full documentation.
See Also
--------
numpy.around : equivalent function
"""
result = self._data.round(decimals=decimals, out=out).view(type(self))
if result.ndim > 0:
result._mask = self._mask
result._update_from(self)
elif self._mask:
# Return masked when the scalar is masked
result = masked
# No explicit output: we're done
if out is None:
return result
if isinstance(out, MaskedArray):
out.__setmask__(self._mask)
return out
def take(self, indices, axis=None, out=None, mode='raise'):
"""
"""
(_data, _mask) = (self._data, self._mask)
cls = type(self)
# Make sure the indices are not masked
maskindices = getattr(indices, '_mask', nomask)
if maskindices is not nomask:
indices = indices.filled(0)
# Get the data
if out is None:
out = _data.take(indices, axis=axis, mode=mode).view(cls)
else:
np.take(_data, indices, axis=axis, mode=mode, out=out)
# Get the mask
if isinstance(out, MaskedArray):
if _mask is nomask:
outmask = maskindices
else:
outmask = _mask.take(indices, axis=axis, mode=mode)
outmask |= maskindices
out.__setmask__(outmask)
return out
# Array methods
def __getstate__(self):
"""Return the internal state of the masked array, for pickling
purposes.
"""
cf = 'CF'[self.flags.fnc]
state = (1,
self.shape,
self.dtype,
self.flags.fnc,
self._data.tobytes(cf),
# self._data.tolist(),
getmaskarray(self).tobytes(cf),
# getmaskarray(self).tolist(),
self._fill_value,
)
return state
def __setstate__(self, state):
"""Restore the internal state of the masked array, for
pickling purposes. ``state`` is typically the output of the
``__getstate__`` output, and is a 5-tuple:
- class name
- a tuple giving the shape of the data
- a typecode for the data
- a binary string for the data
- a binary string for the mask.
"""
(_, shp, typ, isf, raw, msk, flv) = state
super(MaskedArray, self).__setstate__((shp, typ, isf, raw))
self._mask.__setstate__((shp, make_mask_descr(typ), isf, msk))
self.fill_value = flv
def __getitem__(self, indx):
"""
Get the index.
"""
m = self._mask
if isinstance(m[indx], ndarray):
# Can happen when indx is a multi-dimensional field:
# A = ma.masked_array(data=[([0,1],)], mask=[([True,
# False],)], dtype=[("A", ">i2", (2,))])
# x = A[0]; y = x["A"]; then y.mask["A"].size==2
# and we can not say masked/unmasked.
# The result is no longer mvoid!
# See also issue #6724.
return masked_array(
data=self._data[indx], mask=m[indx],
fill_value=self._fill_value[indx],
hard_mask=self._hardmask)
if m is not nomask and m[indx]:
return masked
return self._data[indx]
def filled(self, fill_value=None):
"""
Return a copy with masked fields filled with a given value.
Parameters
----------
fill_value : scalar, optional
The value to use for invalid entries (None by default).
If None, the `fill_value` attribute is used instead.
Returns
-------
filled_void
A `np.void` object
See Also
--------
MaskedArray.filled
"""
return asarray(self).filled(fill_value)[()]
def reduce(self, target, axis=None):
"Reduce target along the given axis."
target = narray(target, copy=False, subok=True)
m = getmask(target)
if axis is not None:
kargs = {'axis': axis}
else:
kargs = {}
target = target.ravel()
if not (m is nomask):
m = m.ravel()
if m is nomask:
t = self.ufunc.reduce(target, **kargs)
else:
target = target.filled(
self.fill_value_func(target)).view(type(target))
t = self.ufunc.reduce(target, **kargs)
m = umath.logical_and.reduce(m, **kargs)
if hasattr(t, '_mask'):
t._mask = m
elif m:
t = masked
return t
def compressed(x):
"""
Return all the non-masked data as a 1-D array.
This function is equivalent to calling the "compressed" method of a
`MaskedArray`, see `MaskedArray.compressed` for details.
See Also
--------
MaskedArray.compressed
Equivalent method.
"""
if not isinstance(x, MaskedArray):
x = asanyarray(x)
return x.compressed()
def left_shift(a, n):
"""
Shift the bits of an integer to the left.
This is the masked array version of `numpy.left_shift`, for details
see that function.
See Also
--------
numpy.left_shift
"""
m = getmask(a)
if m is nomask:
d = umath.left_shift(filled(a), n)
return masked_array(d)
else:
d = umath.left_shift(filled(a, 0), n)
return masked_array(d, mask=m)
def right_shift(a, n):
"""
Shift the bits of an integer to the right.
This is the masked array version of `numpy.right_shift`, for details
see that function.
See Also
--------
numpy.right_shift
"""
m = getmask(a)
if m is nomask:
d = umath.right_shift(filled(a), n)
return masked_array(d)
else:
d = umath.right_shift(filled(a, 0), n)
return masked_array(d, mask=m)
def dump(a, F):
"""
Pickle a masked array to a file.
This is a wrapper around ``cPickle.dump``.
Parameters
----------
a : MaskedArray
The array to be pickled.
F : str or file-like object
The file to pickle `a` to. If a string, the full path to the file.
"""
if not hasattr(F, 'readline'):
F = open(F, 'w')
return pickle.dump(a, F)
def loads(strg):
"""
Load a pickle from the current string.
The result of ``cPickle.loads(strg)`` is returned.
Parameters
----------
strg : str
The string to load.
See Also
--------
dumps : Return a string corresponding to the pickling of a masked array.
"""
return pickle.loads(strg)
def get_masked_subclass(*arrays):
"""
Return the youngest subclass of MaskedArray from a list of (masked) arrays.
In case of siblings, the first listed takes over.
"""
if len(arrays) == 1:
arr = arrays[0]
if isinstance(arr, MaskedArray):
rcls = type(arr)
else:
rcls = MaskedArray
else:
arrcls = [type(a) for a in arrays]
rcls = arrcls[0]
if not issubclass(rcls, MaskedArray):
rcls = MaskedArray
for cls in arrcls[1:]:
if issubclass(cls, rcls):
rcls = cls
# Don't return MaskedConstant as result: revert to MaskedArray
if rcls.__name__ == 'MaskedConstant':
return MaskedArray
return rcls
def outer(self, a, b):
"""
Return the function applied to the outer product of a and b.
"""
(da, db) = (getdata(a), getdata(b))
d = self.f.outer(da, db)
ma = getmask(a)
mb = getmask(b)
if ma is nomask and mb is nomask:
m = nomask
else:
ma = getmaskarray(a)
mb = getmaskarray(b)
m = umath.logical_or.outer(ma, mb)
if (not m.ndim) and m:
return masked
if m is not nomask:
np.copyto(d, da, where=m)
if not d.shape:
return d
masked_d = d.view(get_masked_subclass(a, b))
masked_d._mask = m
return masked_d
def unshare_mask(self):
"""
Copy the mask and set the sharedmask flag to False.
Whether the mask is shared between masked arrays can be seen from
the `sharedmask` property. `unshare_mask` ensures the mask is not shared.
A copy of the mask is only made if it was shared.
See Also
--------
sharedmask
"""
if self._sharedmask:
self._mask = self._mask.copy()
self._sharedmask = False
return self
def resize(self, newshape, refcheck=True, order=False):
"""
.. warning::
This method does nothing, except raise a ValueError exception. A
masked array does not own its data and therefore cannot safely be
resized in place. Use the `numpy.ma.resize` function instead.
This method is difficult to implement safely and may be deprecated in
future releases of NumPy.
"""
# Note : the 'order' keyword looks broken, let's just drop it
errmsg = "A masked array does not own its data "\
"and therefore cannot be resized.\n" \
"Use the numpy.ma.resize function instead."
raise ValueError(errmsg)
def round(self, decimals=0, out=None):
"""
Return an array rounded a to the given number of decimals.
Refer to `numpy.around` for full documentation.
See Also
--------
numpy.around : equivalent function
"""
result = self._data.round(decimals=decimals, out=out).view(type(self))
if result.ndim > 0:
result._mask = self._mask
result._update_from(self)
elif self._mask:
# Return masked when the scalar is masked
result = masked
# No explicit output: we're done
if out is None:
return result
if isinstance(out, MaskedArray):
out.__setmask__(self._mask)
return out
def take(self, indices, axis=None, out=None, mode='raise'):
"""
"""
(_data, _mask) = (self._data, self._mask)
cls = type(self)
# Make sure the indices are not masked
maskindices = getattr(indices, '_mask', nomask)
if maskindices is not nomask:
indices = indices.filled(0)
# Get the data
if out is None:
out = _data.take(indices, axis=axis, mode=mode).view(cls)
else:
np.take(_data, indices, axis=axis, mode=mode, out=out)
# Get the mask
if isinstance(out, MaskedArray):
if _mask is nomask:
outmask = maskindices
else:
outmask = _mask.take(indices, axis=axis, mode=mode)
outmask |= maskindices
out.__setmask__(outmask)
return out
# Array methods
def __getstate__(self):
"""Return the internal state of the masked array, for pickling
purposes.
"""
cf = 'CF'[self.flags.fnc]
state = (1,
self.shape,
self.dtype,
self.flags.fnc,
self._data.tobytes(cf),
# self._data.tolist(),
getmaskarray(self).tobytes(cf),
# getmaskarray(self).tolist(),
self._fill_value,
)
return state
def __setstate__(self, state):
"""Restore the internal state of the masked array, for
pickling purposes. ``state`` is typically the output of the
``__getstate__`` output, and is a 5-tuple:
- class name
- a tuple giving the shape of the data
- a typecode for the data
- a binary string for the data
- a binary string for the mask.
"""
(_, shp, typ, isf, raw, msk, flv) = state
super(MaskedArray, self).__setstate__((shp, typ, isf, raw))
self._mask.__setstate__((shp, make_mask_descr(typ), isf, msk))
self.fill_value = flv
def __getitem__(self, indx):
"""
Get the index.
"""
m = self._mask
if isinstance(m[indx], ndarray):
# Can happen when indx is a multi-dimensional field:
# A = ma.masked_array(data=[([0,1],)], mask=[([True,
# False],)], dtype=[("A", ">i2", (2,))])
# x = A[0]; y = x["A"]; then y.mask["A"].size==2
# and we can not say masked/unmasked.
# The result is no longer mvoid!
# See also issue #6724.
return masked_array(
data=self._data[indx], mask=m[indx],
fill_value=self._fill_value[indx],
hard_mask=self._hardmask)
if m is not nomask and m[indx]:
return masked
return self._data[indx]
def filled(self, fill_value=None):
"""
Return a copy with masked fields filled with a given value.
Parameters
----------
fill_value : scalar, optional
The value to use for invalid entries (None by default).
If None, the `fill_value` attribute is used instead.
Returns
-------
filled_void
A `np.void` object
See Also
--------
MaskedArray.filled
"""
return asarray(self).filled(fill_value)[()]
def reduce(self, target, axis=None):
"Reduce target along the given axis."
target = narray(target, copy=False, subok=True)
m = getmask(target)
if axis is not None:
kargs = {'axis': axis}
else:
kargs = {}
target = target.ravel()
if not (m is nomask):
m = m.ravel()
if m is nomask:
t = self.ufunc.reduce(target, **kargs)
else:
target = target.filled(
self.fill_value_func(target)).view(type(target))
t = self.ufunc.reduce(target, **kargs)
m = umath.logical_and.reduce(m, **kargs)
if hasattr(t, '_mask'):
t._mask = m
elif m:
t = masked
return t
def compressed(x):
"""
Return all the non-masked data as a 1-D array.
This function is equivalent to calling the "compressed" method of a
`MaskedArray`, see `MaskedArray.compressed` for details.
See Also
--------
MaskedArray.compressed
Equivalent method.
"""
if not isinstance(x, MaskedArray):
x = asanyarray(x)
return x.compressed()
def left_shift(a, n):
"""
Shift the bits of an integer to the left.
This is the masked array version of `numpy.left_shift`, for details
see that function.
See Also
--------
numpy.left_shift
"""
m = getmask(a)
if m is nomask:
d = umath.left_shift(filled(a), n)
return masked_array(d)
else:
d = umath.left_shift(filled(a, 0), n)
return masked_array(d, mask=m)
def right_shift(a, n):
"""
Shift the bits of an integer to the right.
This is the masked array version of `numpy.right_shift`, for details
see that function.
See Also
--------
numpy.right_shift
"""
m = getmask(a)
if m is nomask:
d = umath.right_shift(filled(a), n)
return masked_array(d)
else:
d = umath.right_shift(filled(a, 0), n)
return masked_array(d, mask=m)
def dump(a, F):
"""
Pickle a masked array to a file.
This is a wrapper around ``cPickle.dump``.
Parameters
----------
a : MaskedArray
The array to be pickled.
F : str or file-like object
The file to pickle `a` to. If a string, the full path to the file.
"""
if not hasattr(F, 'readline'):
F = open(F, 'w')
return pickle.dump(a, F)
def loads(strg):
"""
Load a pickle from the current string.
The result of ``cPickle.loads(strg)`` is returned.
Parameters
----------
strg : str
The string to load.
See Also
--------
dumps : Return a string corresponding to the pickling of a masked array.
"""
return pickle.loads(strg)
def get_masked_subclass(*arrays):
"""
Return the youngest subclass of MaskedArray from a list of (masked) arrays.
In case of siblings, the first listed takes over.
"""
if len(arrays) == 1:
arr = arrays[0]
if isinstance(arr, MaskedArray):
rcls = type(arr)
else:
rcls = MaskedArray
else:
arrcls = [type(a) for a in arrays]
rcls = arrcls[0]
if not issubclass(rcls, MaskedArray):
rcls = MaskedArray
for cls in arrcls[1:]:
if issubclass(cls, rcls):
rcls = cls
# Don't return MaskedConstant as result: revert to MaskedArray
if rcls.__name__ == 'MaskedConstant':
return MaskedArray
return rcls
def outer(self, a, b):
"""
Return the function applied to the outer product of a and b.
"""
(da, db) = (getdata(a), getdata(b))
d = self.f.outer(da, db)
ma = getmask(a)
mb = getmask(b)
if ma is nomask and mb is nomask:
m = nomask
else:
ma = getmaskarray(a)
mb = getmaskarray(b)
m = umath.logical_or.outer(ma, mb)
if (not m.ndim) and m:
return masked
if m is not nomask:
np.copyto(d, da, where=m)
if not d.shape:
return d
masked_d = d.view(get_masked_subclass(a, b))
masked_d._mask = m
masked_d._update_from(d)
return masked_d
def __call__(self, *args, **params):
methodname = self.__name__
instance = self.obj
# Fallback : if the instance has not been initialized, use the first
# arg
if instance is None:
args = list(args)
instance = args.pop(0)
data = instance._data
mask = instance._mask
cls = type(instance)
result = getattr(data, methodname)(*args, **params).view(cls)
result._update_from(instance)
if result.ndim:
if not self._onmask:
result.__setmask__(mask)
elif mask is not nomask:
result.__setmask__(getattr(mask, methodname)(*args, **params))
else:
if mask.ndim and (not mask.dtype.names and mask.all()):
return masked
return result
def unshare_mask(self):
"""
Copy the mask and set the sharedmask flag to False.
Whether the mask is shared between masked arrays can be seen from
the `sharedmask` property. `unshare_mask` ensures the mask is not shared.
A copy of the mask is only made if it was shared.
See Also
--------
sharedmask
"""
if self._sharedmask:
self._mask = self._mask.copy()
self._sharedmask = False
return self
def common_fill_value(a, b):
"""
Return the common filling value of two masked arrays, if any.
If ``a.fill_value == b.fill_value``, return the fill value,
otherwise return None.
Parameters
----------
a, b : MaskedArray
The masked arrays for which to compare fill values.
Returns
-------
fill_value : scalar or None
The common fill value, or None.
Examples
--------
>>> x = np.ma.array([0, 1.], fill_value=3)
>>> y = np.ma.array([0, 1.], fill_value=3)
>>> np.ma.common_fill_value(x, y)
3.0
"""
t1 = get_fill_value(a)
t2 = get_fill_value(b)
if t1 == t2:
return t1
return None
def __str__(self):
return "Masked version of %s. [Invalid values are masked]" % str(self.f)
def reduce(self, target, axis=0, dtype=None):
"""
Reduce `target` along the given `axis`.
"""
tclass = get_masked_subclass(target)
m = getmask(target)
t = filled(target, self.filly)
if t.shape == ():
t = t.reshape(1)
if m is not nomask:
m = make_mask(m, copy=1)
m.shape = (1,)
if m is nomask:
tr = self.f.reduce(t, axis)
mr = nomask
else:
tr = self.f.reduce(t, axis, dtype=dtype or t.dtype)
mr = umath.logical_and.reduce(m, axis)
if not tr.shape:
if mr:
return masked
else:
return tr
masked_tr = tr.view(tclass)
masked_tr._mask = mr
return masked_tr
def _check_mask_axis(mask, axis):
"Check whether there are masked values along the given axis"
if mask is not nomask:
return mask.all(axis=axis)
return nomask
###############################################################################
# Masking functions #
###############################################################################
def display(self):
"""
Display the string to print for masked values.
"""
return self._display
def set_display(self, s):
"""
Set the string to print for masked values.
"""
self._display = s
def __getitem__(self, indx):
result = self.dataiter.__getitem__(indx).view(type(self.ma))
if self.maskiter is not None:
_mask = self.maskiter.__getitem__(indx)
if isinstance(_mask, ndarray):
# set shape to match that of data; this is needed for matrices
_mask.shape = result.shape
result._mask = _mask
elif isinstance(_mask, np.void):
return mvoid(result, mask=_mask, hardmask=self.ma._hardmask)
elif _mask: # Just a scalar, masked
return masked
return result
# This won't work if ravel makes a copy
def __next__(self):
"""
Return the next value, or raise StopIteration.
Examples
--------
>>> x = np.ma.array([3, 2], mask=[0, 1])
>>> fl = x.flat
>>> fl.next()
3
>>> fl.next()
masked_array(data = --,
mask = True,
fill_value = 1e+20)
>>> fl.next()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/ralf/python/numpy/numpy/ma/core.py", line 2243, in next
d = self.dataiter.next()
StopIteration
"""
d = next(self.dataiter)
if self.maskiter is not None:
m = next(self.maskiter)
if isinstance(m, np.void):
return mvoid(d, mask=m, hardmask=self.ma._hardmask)
elif m: # Just a scalar, masked
return masked
return d
def __setslice__(self, i, j, value):
"""
x.__setslice__(i, j, value) <==> x[i:j]=value
Set the slice (i,j) of a to value. If value is masked, mask those
locations.
"""
self.__setitem__(slice(i, j), value)
def _set_recordmask(self):
"""
Return the mask of the records.
A record is masked when all the fields are masked.
"""
raise NotImplementedError("Coming soon: setting the mask per records!")
def harden_mask(self):
"""
Force the mask to hard.
Whether the mask of a masked array is hard or soft is determined by
its `hardmask` property. `harden_mask` sets `hardmask` to True.
See Also
--------
hardmask
"""
self._hardmask = True
return self
def soften_mask(self):
"""
Force the mask to soft.
Whether the mask of a masked array is hard or soft is determined by
its `hardmask` property. `soften_mask` sets `hardmask` to False.
See Also
--------
hardmask
"""
self._hardmask = False
return self
def get_fill_value(self):
"""
Return the filling value of the masked array.
Returns
-------
fill_value : scalar
The filling value.
Examples
--------
>>> for dt in [np.int32, np.int64, np.float64, np.complex128]:
... np.ma.array([0, 1], dtype=dt).get_fill_value()
...
999999
999999
1e+20
(1e+20+0j)
>>> x = np.ma.array([0, 1.], fill_value=-np.inf)
>>> x.get_fill_value()
-inf
"""
if self._fill_value is None:
self._fill_value = _check_fill_value(None, self.dtype)
return self._fill_value[()]
def compressed(self):
"""
Return all the non-masked data as a 1-D array.
Returns
-------
data : ndarray
A new `ndarray` holding the non-masked data is returned.
Notes
-----
The result is **not** a MaskedArray!
Examples
--------
>>> x = np.ma.array(np.arange(5), mask=[0]*2 + [1]*3)
>>> x.compressed()
array([0, 1])
>>> type(x.compressed())
<type 'numpy.ndarray'>
"""
data = ndarray.ravel(self._data)
if self._mask is not nomask:
data = data.compress(np.logical_not(ndarray.ravel(self._mask)))
return data