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author | Pauli Virtanen <pav@iki.fi> | 2009-10-02 19:27:46 +0000 |
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committer | Pauli Virtanen <pav@iki.fi> | 2009-10-02 19:27:46 +0000 |
commit | 1521f6689a3cc48d60a75097a7ffcf4d51f9dc47 (patch) | |
tree | a0f048838717b7ee43177007ec42c3102ea7be25 /numpy/ma/core.py | |
parent | 8c7d1bc554e6b5bbb7900a2f6d976d72795bb454 (diff) | |
download | numpy-1521f6689a3cc48d60a75097a7ffcf4d51f9dc47.tar.gz |
Docstring updates, part 1
Diffstat (limited to 'numpy/ma/core.py')
-rw-r--r-- | numpy/ma/core.py | 170 |
1 files changed, 153 insertions, 17 deletions
diff --git a/numpy/ma/core.py b/numpy/ma/core.py index baf54b5b0..2045ee73b 100644 --- a/numpy/ma/core.py +++ b/numpy/ma/core.py @@ -154,7 +154,42 @@ if 'float128' in ntypes.typeDict: def default_fill_value(obj): """ - Calculate the default fill value for the argument object. + Return the default fill value for the argument object. + + The default filling value depends on the datatype of the input + array or the type of the input scalar: + + ======== ======== + datatype default + ======== ======== + bool True + int 999999 + float 1.e20 + complex 1.e20+0j + object '?' + string 'N/A' + ======== ======== + + + Parameters + ---------- + obj : ndarray, dtype or scalar + The array data-type or scalar for which the default fill value + is returned. + + Returns + ------- + fill_value : scalar + The default fill value. + + Examples + -------- + >>> np.ma.default_fill_value(1) + 999999 + >>> np.ma.default_fill_value(np.array([1.1, 2., np.pi])) + 1e+20 + >>> np.ma.default_fill_value(np.dtype(complex)) + (1e+20+0j) """ if hasattr(obj,'dtype'): @@ -2213,7 +2248,52 @@ class _arraymethod(object): #.......................................................... class MaskedIterator(object): - "Define an interator." + """ + Flat iterator object to iterate over masked arrays. + + A `MaskedIterator` iterator is returned by ``x.flat`` for any masked array + `x`. It allows iterating over the array as if it were a 1-D array, + either in a for-loop or by calling its `next` method. + + Iteration is done in C-contiguous style, with the last index varying the + fastest. The iterator can also be indexed using basic slicing or + advanced indexing. + + See Also + -------- + MaskedArray.flat : Return a flat iterator over an array. + MaskedArray.flatten : Returns a flattened copy of an array. + + Notes + ----- + `MaskedIterator` is not exported by the `ma` module. Instead of + instantiating a `MaskedIterator` directly, use `MaskedArray.flat`. + + Examples + -------- + >>> x = np.ma.array(arange(6).reshape(2, 3)) + >>> fl = x.flat + >>> type(fl) + <class 'numpy.ma.core.MaskedIterator'> + >>> for item in fl: + ... print item + ... + 0 + 1 + 2 + 3 + 4 + 5 + + Extracting more than a single element b indexing the `MaskedIterator` + returns a masked array: + + >>> fl[2:4] + masked_array(data = [2 3], + mask = False, + fill_value = 999999) + + """ def __init__(self, ma): self.ma = ma self.dataiter = ma._data.flat @@ -3952,12 +4032,51 @@ class MaskedArray(ndarray): def mean(self, axis=None, dtype=None, out=None): """ - Returns the average of the array elements along given axis. - Refer to `numpy.mean` for full documentation. + Returns the average of the array elements. + + Masked entries are ignored. + The average is taken over the flattened array by default, otherwise over + the specified axis. Refer to `numpy.mean` for the full documentation. + + Parameters + ---------- + a : array_like + Array containing numbers whose mean is desired. If `a` is not an + array, a conversion is attempted. + axis : int, optional + Axis along which the means are computed. The default is to compute + the mean of the flattened array. + dtype : dtype, optional + Type to use in computing the mean. For integer inputs, the default + is float64; for floating point, inputs it is the same as the input + dtype. + out : ndarray, optional + Alternative output array in which to place the result. It must have + the same shape as the expected output but the type will be cast if + necessary. + + Returns + ------- + mean : ndarray, see dtype parameter above + If `out=None`, returns a new array containing the mean values, + otherwise a reference to the output array is returned. + + See Also + -------- + numpy.ma.mean : Equivalent function. + numpy.mean : Equivalent function on non-masked arrays. + numpy.ma.average: Weighted average. + + Examples + -------- + >>> a = np.ma.array([1,2,3], mask=[False, False, True]) + >>> a + masked_array(data = [1 2 --], + mask = [False False True], + fill_value = 999999) + >>> a.mean() + 1.5 - See Also - -------- - numpy.mean : equivalent function' """ if self._mask is nomask: result = super(MaskedArray, self).mean(axis=axis, dtype=dtype) @@ -3977,18 +4096,35 @@ class MaskedArray(ndarray): def anom(self, axis=None, dtype=None): """ - Return the anomalies (deviations from the average) along the given axis. + Compute the anomalies (deviations from the arithmetic mean) + along the given axis. - Parameters - ---------- - axis : int, optional - Axis along which to perform the operation. - If None, applies to a flattened version of the array. - dtype : {dtype}, optional - Datatype for the intermediary computation. - If not given, the current dtype is used instead. + Returns an array of anomalies, with the same shape as the input and + where the arithmetic mean is computed along the given axis. - """ + Parameters + ---------- + axis : int, optional + Axis over which the anomalies are taken. + The default is to use the mean of the flattened array as reference. + dtype : dtype, optional + Type to use in computing the variance. For arrays of integer type + the default is float32; for arrays of float types it is the same as + the array type. + + See Also + -------- + mean : Compute the mean of the array. + + Examples + -------- + >>> a = np.ma.array([1,2,3]) + >>> a.anom() + masked_array(data = [-1. 0. 1.], + mask = False, + fill_value = 1e+20) + + """ m = self.mean(axis, dtype) if not axis: return (self - m) |