def choose(a, choices, out=None, mode='<STR_LIT>'):
try:<EOL><INDENT>choose = a.choose<EOL><DEDENT>except AttributeError:<EOL><INDENT>return _wrapit(a, '<STR_LIT>', choices, out=out, mode=mode)<EOL><DEDENT>return choose(choices, out=out, mode=mode)<EOL>
Construct an array from an index array and a set of arrays to choose from.

First of all, if confused or uncertain, definitely look at the Examples -
in its full generality, this function is less simple than it might
seem from the following code description (below ndi =
`numpy.lib.index_tricks`):

``np.choose(a,c) == np.array([c[a[I]][I] for I in ndi.ndindex(a.shape)])``.

But this omits some subtleties.  Here is a fully general summary:

Given an "index" array (`a`) of integers and a sequence of `n` arrays
(`choices`), `a` and each choice array are first broadcast, as necessary,
to arrays of a common shape; calling these *Ba* and *Bchoices[i], i =
0,...,n-1* we have that, necessarily, ``Ba.shape == Bchoices[i].shape``
for each `i`.  Then, a new array with shape ``Ba.shape`` is created as
follows:

* if ``mode=raise`` (the default), then, first of all, each element of
  `a` (and thus `Ba`) must be in the range `[0, n-1]`; now, suppose that
  `i` (in that range) is the value at the `(j0, j1, ..., jm)` position
  in `Ba` - then the value at the same position in the new array is the
  value in `Bchoices[i]` at that same position;

* if ``mode=wrap``, values in `a` (and thus `Ba`) may be any (signed)
  integer; modular arithmetic is used to map integers outside the range
  `[0, n-1]` back into that range; and then the new array is constructed
  as above;

* if ``mode=clip``, values in `a` (and thus `Ba`) may be any (signed)
  integer; negative integers are mapped to 0; values greater than `n-1`
  are mapped to `n-1`; and then the new array is constructed as above.

Parameters
----------
a : int array
    This array must contain integers in `[0, n-1]`, where `n` is the number
    of choices, unless ``mode=wrap`` or ``mode=clip``, in which cases any
    integers are permissible.
choices : sequence of arrays
    Choice arrays. `a` and all of the choices must be broadcastable to the
    same shape.  If `choices` is itself an array (not recommended), then
    its outermost dimension (i.e., the one corresponding to
    ``choices.shape[0]``) is taken as defining the "sequence".
out : array, optional
    If provided, the result will be inserted into this array. It should
    be of the appropriate shape and dtype.
mode : {'raise' (default), 'wrap', 'clip'}, optional
    Specifies how indices outside `[0, n-1]` will be treated:

      * 'raise' : an exception is raised
      * 'wrap' : value becomes value mod `n`
      * 'clip' : values < 0 are mapped to 0, values > n-1 are mapped to n-1

Returns
-------
merged_array : array
    The merged result.

Raises
------
ValueError: shape mismatch
    If `a` and each choice array are not all broadcastable to the same
    shape.

See Also
--------
ndarray.choose : equivalent method

Notes
-----
To reduce the chance of misinterpretation, even though the following
"abuse" is nominally supported, `choices` should neither be, nor be
thought of as, a single array, i.e., the outermost sequence-like container
should be either a list or a tuple.

Examples
--------

>>> choices = [[0, 1, 2, 3], [10, 11, 12, 13],
...   [20, 21, 22, 23], [30, 31, 32, 33]]
>>> np.choose([2, 3, 1, 0], choices
... # the first element of the result will be the first element of the
... # third (2+1) "array" in choices, namely, 20; the second element
... # will be the second element of the fourth (3+1) choice array, i.e.,
... # 31, etc.
... )
array([20, 31, 12,  3])
>>> np.choose([2, 4, 1, 0], choices, mode='clip') # 4 goes to 3 (4-1)
array([20, 31, 12,  3])
>>> # because there are 4 choice arrays
>>> np.choose([2, 4, 1, 0], choices, mode='wrap') # 4 goes to (4 mod 4)
array([20,  1, 12,  3])
>>> # i.e., 0

A couple examples illustrating how choose broadcasts:

>>> a = [[1, 0, 1], [0, 1, 0], [1, 0, 1]]
>>> choices = [-10, 10]
>>> np.choose(a, choices)
array([[ 10, -10,  10],
       [-10,  10, -10],
       [ 10, -10,  10]])

>>> # With thanks to Anne Archibald
>>> a = np.array([0, 1]).reshape((2,1,1))
>>> c1 = np.array([1, 2, 3]).reshape((1,3,1))
>>> c2 = np.array([-1, -2, -3, -4, -5]).reshape((1,1,5))
>>> np.choose(a, (c1, c2)) # result is 2x3x5, res[0,:,:]=c1, res[1,:,:]=c2
array([[[ 1,  1,  1,  1,  1],
        [ 2,  2,  2,  2,  2],
        [ 3,  3,  3,  3,  3]],
       [[-1, -2, -3, -4, -5],
        [-1, -2, -3, -4, -5],
        [-1, -2, -3, -4, -5]]])