numpy.asfortranarray() in Python

numpy.asfortranarray() function is used when we want to convert input to a array which is laid out in Fortran order in memory. Input includes scalar, lists, lists of tuples, tuples, tuples of tuples, tuples of lists and ndarrays.

Syntax : numpy.asfortranarray(arr, dtype=None)

Parameters :
arr : [array_like] Input data, in any form that can be converted to an float type array. This includes scalar, lists, lists of tuples, tuples, tuples of tuples, tuples of lists and ndarrays.
dtype : By default, the data-type is inferred from the input data.

Return : The input arr in Fortran, or column-major, order.

Code #1 : List to fortranarray



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# Python program explaining
# numpy.asfortranarray() function
  
import numpy as geek
my_list = [1, 3, 5, 7, 9]
  
print ("Input  list : ", my_list)
   
    
out_arr = geek.asfortranarray(my_list)
print ("output fortanarray from input list : ", out_arr) 

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Output :

Input  list :  [1, 3, 5, 7, 9]
output fortanarray from input list :  [1 3 5 7 9]

 
Code #2 : Tuple to fortanarray

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# Python program explaining
# numpy.asfortranarray() function
  
import numpy as geek
  
my_tuple = ([1, 3, 9], [8, 2, 6])
   
print ("Input  tuple : ", my_tuple)
    
out_arr = geek.asfortranarray(my_tuple, dtype ='int8'
print ("output fortan array from input tuple : ", out_arr) 

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Output :

Input  tuple :  ([1, 3, 9], [8, 2, 6])
output fortan array from input touple :  [[1 3 9]
 [8 2 6]]

 
Code #3 : Scalar to fortanarray

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# Python program explaining
# numpy.asfortranarray() function
  
import numpy as geek
  
my_scalar = 15
   
print ("Input  scalar : ", my_scalar)
    
out_arr = geek.asfortranarray(my_scalar, dtype ='float'
print ("output fortan array from input scalar : ", out_arr) 

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Output :

Input  scalar :  15
output fortan array from input scalar :  [ 15.]

 
Code #4 : array to fortanarray

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# Python program explaining
# numpy.asfortranarray() function
  
import numpy as geek
  
in_arr = geek.arange(9).reshape(3, 3)
   
print ("Input  array : ", in_arr)
  
# checking if it is fortanarray
print(in_arr.flags['F_CONTIGUOUS'])
  
out_arr = geek.asfortranarray(in_arr, dtype ='float'
print ("output array from input array : ", out_arr) 
  
# checking if it has become fortanarray
print(out_arr.flags['F_CONTIGUOUS'])

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Output :

Input  array :  [[0 1 2]
 [3 4 5]
 [6 7 8]]
False
output array from input array :  [[ 0.  1.  2.]
 [ 3.  4.  5.]
 [ 6.  7.  8.]]
True


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