numpy.ma.choose() function – Python

numpy.ma.choose() function use an index array to construct a new array from a set of choices. Given an array of integers and a set of n choice arrays, this method will create a new array that merges each of the choice arrays. Where arr value in arr is i, the new array will have the value that choices[i] contains in the same place.

Syntax : numpy.ma.choose(arr, choices, out = None, mode = ‘raise’)

Parameters :
arr : [ndarray of ints] This array must contain integers in [0, n-1], where n is the number of choices.
choices : [sequence of arrays] Choice arrays. The index array and all of the choices should be broadcastable to the same shape.
out : [array, optional] If provided, the result will be inserted into this array. It should be of the appropriate shape and dtype.
mode : [{‘raise’, ‘wrap’, ‘clip’}, optional] Specifies how out-of-bounds indices will behave. ‘raise’: raise an error. ‘wrap’: wrap around. ‘clip’: clip to the range.

Return : A new array that merges each of the choice arrays.

Code #1 :

Output :

[3 2 1]

 
Code #2 :

Output :

[1 2 3]