Numpy.lexsort() function with example in python

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Syntax: numpy.lexsort
numpy.lexsort(keys, axis=-1)
Description : Perform an indirect stable sort using a sequence of keys.

Given multiple sorting keys, which can be interpreted as columns in a spreadsheet, lexsort returns an array of integer indices that describes the sort order by multiple columns. The last key in the sequence is used for the primary sort order, the second-to-last key for the secondary sort order, and so on. The keys argument must be a sequence of objects that can be converted to arrays of the same shape. If a 2D array is provided for the keys argument, it’s rows are interpreted as the sorting keys and sorting is according to the last row, second last row etc.

keys : (k, N) array or tuple containing k (N,)-shaped sequences
The k different “columns” to be sorted. The last column (or row if keys is a 2D array) is the primary sort key.

axis : int, optional
Axis to be indirectly sorted. By default, sort over the last axis.

indices : (N,) ndarray of ints
Array of indices that sort the keys along the specified axis.


Numpy.lexsort() function Example program 

import numpy as np surnames = ('Hertz', 'Galilei', 'Hertz') first_names = ('Heinrich', 'Galileo', 'Gustav') ind = np.lexsort((first_names, surnames)) print(ind)



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