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Diffstat (limited to 'doc/source/reference/maskedarray.generic.rst')
| -rw-r--r-- | doc/source/reference/maskedarray.generic.rst | 170 |
1 files changed, 85 insertions, 85 deletions
diff --git a/doc/source/reference/maskedarray.generic.rst b/doc/source/reference/maskedarray.generic.rst index 7375d60fb..41c3ee564 100644 --- a/doc/source/reference/maskedarray.generic.rst +++ b/doc/source/reference/maskedarray.generic.rst @@ -74,7 +74,7 @@ To create an array with the second element invalid, we would do:: To create a masked array where all values close to 1.e20 are invalid, we would do:: - >>> z = masked_values([1.0, 1.e20, 3.0, 4.0], 1.e20) + >>> z = ma.masked_values([1.0, 1.e20, 3.0, 4.0], 1.e20) For a complete discussion of creation methods for masked arrays please see section :ref:`Constructing masked arrays <maskedarray.generic.constructing>`. @@ -110,15 +110,15 @@ There are several ways to construct a masked array. >>> x = np.array([1, 2, 3]) >>> x.view(ma.MaskedArray) - masked_array(data = [1 2 3], - mask = False, - fill_value = 999999) + masked_array(data=[1, 2, 3], + mask=False, + fill_value=999999) >>> x = np.array([(1, 1.), (2, 2.)], dtype=[('a',int), ('b', float)]) >>> x.view(ma.MaskedArray) - masked_array(data = [(1, 1.0) (2, 2.0)], - mask = [(False, False) (False, False)], - fill_value = (999999, 1e+20), - dtype = [('a', '<i4'), ('b', '<f8')]) + masked_array(data=[(1, 1.0), (2, 2.0)], + mask=[(False, False), (False, False)], + fill_value=(999999, 1.e+20), + dtype=[('a', '<i8'), ('b', '<f8')]) * Yet another possibility is to use any of the following functions: @@ -195,9 +195,9 @@ index. The inverse of the mask can be calculated with the >>> x = ma.array([[1, 2], [3, 4]], mask=[[0, 1], [1, 0]]) >>> x[~x.mask] - masked_array(data = [1 4], - mask = [False False], - fill_value = 999999) + masked_array(data=[1, 4], + mask=[False, False], + fill_value=999999) Another way to retrieve the valid data is to use the :meth:`compressed` method, which returns a one-dimensional :class:`~numpy.ndarray` (or one of its @@ -223,27 +223,26 @@ as invalid is to assign the special value :attr:`masked` to them:: >>> x = ma.array([1, 2, 3]) >>> x[0] = ma.masked >>> x - masked_array(data = [-- 2 3], - mask = [ True False False], - fill_value = 999999) + masked_array(data=[--, 2, 3], + mask=[ True, False, False], + fill_value=999999) >>> y = ma.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) >>> y[(0, 1, 2), (1, 2, 0)] = ma.masked >>> y - masked_array(data = - [[1 -- 3] - [4 5 --] - [-- 8 9]], - mask = - [[False True False] - [False False True] - [ True False False]], - fill_value = 999999) + masked_array( + data=[[1, --, 3], + [4, 5, --], + [--, 8, 9]], + mask=[[False, True, False], + [False, False, True], + [ True, False, False]], + fill_value=999999) >>> z = ma.array([1, 2, 3, 4]) >>> z[:-2] = ma.masked >>> z - masked_array(data = [-- -- 3 4], - mask = [ True True False False], - fill_value = 999999) + masked_array(data=[--, --, 3, 4], + mask=[ True, True, False, False], + fill_value=999999) A second possibility is to modify the :attr:`~MaskedArray.mask` directly, @@ -263,9 +262,10 @@ mask:: >>> x = ma.array([1, 2, 3], mask=[0, 0, 1]) >>> x.mask = True >>> x - masked_array(data = [-- -- --], - mask = [ True True True], - fill_value = 999999) + masked_array(data=[--, --, --], + mask=[ True, True, True], + fill_value=999999, + dtype=int64) Finally, specific entries can be masked and/or unmasked by assigning to the mask a sequence of booleans:: @@ -273,9 +273,9 @@ mask a sequence of booleans:: >>> x = ma.array([1, 2, 3]) >>> x.mask = [0, 1, 0] >>> x - masked_array(data = [1 -- 3], - mask = [False True False], - fill_value = 999999) + masked_array(data=[1, --, 3], + mask=[False, True, False], + fill_value=999999) Unmasking an entry ~~~~~~~~~~~~~~~~~~ @@ -285,14 +285,14 @@ new valid values to them:: >>> x = ma.array([1, 2, 3], mask=[0, 0, 1]) >>> x - masked_array(data = [1 2 --], - mask = [False False True], - fill_value = 999999) + masked_array(data=[1, 2, --], + mask=[False, False, True], + fill_value=999999) >>> x[-1] = 5 >>> x - masked_array(data = [1 2 5], - mask = [False False False], - fill_value = 999999) + masked_array(data=[1, 2, 5], + mask=[False, False, False], + fill_value=999999) .. note:: Unmasking an entry by direct assignment will silently fail if the masked @@ -304,21 +304,27 @@ new valid values to them:: >>> x = ma.array([1, 2, 3], mask=[0, 0, 1], hard_mask=True) >>> x - masked_array(data = [1 2 --], - mask = [False False True], - fill_value = 999999) + masked_array(data=[1, 2, --], + mask=[False, False, True], + fill_value=999999) >>> x[-1] = 5 >>> x - masked_array(data = [1 2 --], - mask = [False False True], - fill_value = 999999) + masked_array(data=[1, 2, --], + mask=[False, False, True], + fill_value=999999) >>> x.soften_mask() + masked_array(data=[1, 2, --], + mask=[False, False, True], + fill_value=999999) >>> x[-1] = 5 >>> x - masked_array(data = [1 2 5], - mask = [False False False], - fill_value = 999999) + masked_array(data=[1, 2, 5], + mask=[False, False, False], + fill_value=999999) >>> x.harden_mask() + masked_array(data=[1, 2, 5], + mask=[False, False, False], + fill_value=999999) To unmask all masked entries of a masked array (provided the mask isn't a hard @@ -327,15 +333,14 @@ mask:: >>> x = ma.array([1, 2, 3], mask=[0, 0, 1]) >>> x - masked_array(data = [1 2 --], - mask = [False False True], - fill_value = 999999) + masked_array(data=[1, 2, --], + mask=[False, False, True], + fill_value=999999) >>> x.mask = ma.nomask >>> x - masked_array(data = [1 2 3], - mask = [False False False], - fill_value = 999999) - + masked_array(data=[1, 2, 3], + mask=[False, False, False], + fill_value=999999) Indexing and slicing @@ -353,9 +358,7 @@ the mask is ``True``):: >>> x[0] 1 >>> x[-1] - masked_array(data = --, - mask = True, - fill_value = 1e+20) + masked >>> x[-1] is ma.masked True @@ -370,10 +373,7 @@ is masked. >>> y[0] (1, 2) >>> y[-1] - masked_array(data = (3, --), - mask = (False, True), - fill_value = (999999, 999999), - dtype = [('a', '<i4'), ('b', '<i4')]) + (3, --) When accessing a slice, the output is a masked array whose @@ -385,20 +385,19 @@ required to ensure propagation of any modification of the mask to the original. >>> x = ma.array([1, 2, 3, 4, 5], mask=[0, 1, 0, 0, 1]) >>> mx = x[:3] >>> mx - masked_array(data = [1 -- 3], - mask = [False True False], - fill_value = 999999) + masked_array(data=[1, --, 3], + mask=[False, True, False], + fill_value=999999) >>> mx[1] = -1 >>> mx - masked_array(data = [1 -1 3], - mask = [False False False], - fill_value = 999999) + masked_array(data=[1, -1, 3], + mask=[False, False, False], + fill_value=999999) >>> x.mask - array([False, True, False, False, True]) + array([False, False, False, False, True]) >>> x.data array([ 1, -1, 3, 4, 5]) - Accessing a field of a masked array with structured datatype returns a :class:`MaskedArray`. @@ -421,9 +420,9 @@ ufuncs. Unary and binary functions that have a validity domain (such as constant whenever the input is masked or falls outside the validity domain:: >>> ma.log([-1, 0, 1, 2]) - masked_array(data = [-- -- 0.0 0.69314718056], - mask = [ True True False False], - fill_value = 1e+20) + masked_array(data=[--, --, 0.0, 0.6931471805599453], + mask=[ True, True, False, False], + fill_value=1e+20) Masked arrays also support standard numpy ufuncs. The output is then a masked array. The result of a unary ufunc is masked wherever the input is masked. The @@ -435,10 +434,9 @@ input fall outside the validity domain:: >>> x = ma.array([-1, 1, 0, 2, 3], mask=[0, 0, 0, 0, 1]) >>> np.log(x) - masked_array(data = [-- -- 0.0 0.69314718056 --], - mask = [ True True False False True], - fill_value = 1e+20) - + masked_array(data=[--, 0.0, --, 0.6931471805599453, --], + mask=[ True, False, True, False, True], + fill_value=1e+20) Examples @@ -454,11 +452,11 @@ of anomalies (deviations from the average):: >>> import numpy.ma as ma >>> x = [0.,1.,-9999.,3.,4.] >>> mx = ma.masked_values (x, -9999.) - >>> print mx.mean() + >>> print(mx.mean()) 2.0 - >>> print mx - mx.mean() + >>> print(mx - mx.mean()) [-2.0 -1.0 -- 1.0 2.0] - >>> print mx.anom() + >>> print(mx.anom()) [-2.0 -1.0 -- 1.0 2.0] @@ -468,7 +466,7 @@ Filling in the missing data Suppose now that we wish to print that same data, but with the missing values replaced by the average value. - >>> print mx.filled(mx.mean()) + >>> print(mx.filled(mx.mean())) [ 0. 1. 2. 3. 4.] @@ -478,10 +476,10 @@ Numerical operations Numerical operations can be easily performed without worrying about missing values, dividing by zero, square roots of negative numbers, etc.:: - >>> import numpy as np, numpy.ma as ma + >>> import numpy.ma as ma >>> x = ma.array([1., -1., 3., 4., 5., 6.], mask=[0,0,0,0,1,0]) >>> y = ma.array([1., 2., 0., 4., 5., 6.], mask=[0,0,0,0,0,1]) - >>> print np.sqrt(x/y) + >>> print(ma.sqrt(x/y)) [1.0 -- -- 1.0 -- --] Four values of the output are invalid: the first one comes from taking the @@ -492,8 +490,10 @@ the last two where the inputs were masked. Ignoring extreme values ----------------------- -Let's consider an array ``d`` of random floats between 0 and 1. We wish to +Let's consider an array ``d`` of floats between 0 and 1. We wish to compute the average of the values of ``d`` while ignoring any data outside -the range ``[0.1, 0.9]``:: +the range ``[0.2, 0.9]``:: - >>> print ma.masked_outside(d, 0.1, 0.9).mean() + >>> d = np.linspace(0, 1, 20) + >>> print(d.mean() - ma.masked_outside(d, 0.2, 0.9).mean()) + -0.05263157894736836 |