  # How to Sort a Numpy Array | python

NumPy | Python Methods and Functions

Example # 1: Just sort the given array based on the axis using the sort () method.

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 ` # import libraries ` ` import ` ` numpy as np ` ` `  ` # sort by first axis ` ` a ` ` = ` ` np.array ([[` ` 12 ` `, ` ` 15 ` `], [` ` 10 ` `, ` ` 1 ` `]]) ` ` arr1 ` ` = ` ` np.sort (a, axis ` ` = ` ` 0 ` `) `   ` print ` ` (` ` "Along first axis:" ` `, arr1) `     ` # sort by last axis ` ` a ` ` = ` ` np.array ([[` ` 10 ` `, ` ` 15 ` `], [` ` 12 ` `, ` ` 1 ` `]]) ` ` arr2 ` ` = ` ` np.sort (a, axis ` ` = ` ` - ` ` 1 ` `) ` ` print ` ` (` ` "Along first axis:" , arr2) ``     a = np.array ([[ 12 , 15 ], [ 10 , 1 ]]) arr1 = np.sort (a, axis = None )  print ( "Along none axis: " , arr1) `

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Exit:

` Along first axis: [[10 1] [12 15]] Along first axis: [[10 15] [1 12]] Along none axis: [1 10 1 2 15] `

Example # 2: Get the indexes that a sorted array can return using the argsort () method

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` # Python code for demo # working of numpy.argsort import numpy as np   # Numpy array created a = np.array ([ 9 , 3 , 1 , 7 , 4 , 3 , < code class = "value"> 6 ])   # unsorted print array print ( `Original array:` , a)    # Sort array indices b = np.argsort (a) print ( `Sorted indices of original array- & gt;` , b)   # Get a sorted array using sorted indices # c is a temporary array created from the same len as b c = np.zeros ( len ( b), dtype = int ) for i in range ( 0 , len (b)):   c [i] = a [b [i]] print ( `Sorted array- & gt;` , c) `

Output:

` Original array: [9 3 1 7 4 3 6] Sorted indices of original array- & gt; [2 1 5 4 6 3 0] Sorted array- & gt; [1 3 3 4 6 7 9] `

Example # 3: Get a stable sort using a sequence of keys.

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` import numpy as np    # Numpy array created # First column a = np.array ([ 9 , 3 , 1 , 3 , 4 , 3 , 6 ])    # Second column b = np.array ([ 4 , 6 , 9 , 2 , 1 , 8 , 7 ])  print ( `column a, column b` ) for (i, j) in zip (a, b) : print (i, `` , j)    # Sort by then by b ind = np.lexsort ((b, a))  print ( `Sorted indices- & gt;` , ind) `

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Exit :

` column a, column b 9 4 3 6 1 9 3 2 4 1 3 8 6 7 Sorted indices- & gt; [2 3 1 5 4 6 0] `