I am trying to iterate a numpy 2D array in a for loop. why is the output repeating itself-CodePudding

please tell what am I doing wrong here the output is repeated

import numpy as np

hj = np.array([[2, 3, 0], [6, 5, 7], [8, 9, 7], [1, 1, 1]])
print(hj)

print("2-D")
grr = hj

for x in grr:
    for y in grr:
        print(grr)

I even tried to do hj = np.arange(0, 10).reshape(5, 2)

I also did

import numpy as np

hj = np.array([[2, 3, 0], [6, 5, 7], [8, 9, 7], [1, 1, 1]])
# hj = np.arange(0, 10).reshape(5, 2)
# print(hj)

print("2-D")

for x in hj:
    for y in hj:
        print(hj)

CodePudding user response：

In [25]: arr = np.array([[1,2],[3,4]])

Lets look in more detail at what the variables are in the loop:

In [26]: for x in arr:
    ...:     print('%r %r'%(x, arr))
    ...:     for y in x:
    ...:         print('%r %r %r'%(y, x, arr))
    ...: 
array([1, 2]) array([[1, 2],       # a (2,) and (2,2) array
       [3, 4]])
1 array([1, 2]) array([[1, 2],     # a scalar, a (2,) and (2,2)
       [3, 4]])
2 array([1, 2]) array([[1, 2],
       [3, 4]])
array([3, 4]) array([[1, 2],
       [3, 4]])
3 array([3, 4]) array([[1, 2],
       [3, 4]])
4 array([3, 4]) array([[1, 2],
       [3, 4]])

You could use a double list comprehension to produce a list of lists:

In [27]: [[y for y in x] for x in arr]
Out[27]: [[1, 2], [3, 4]]
In [28]: arr.tolist()             # faster
Out[28]: [[1, 2], [3, 4]]

CodePudding user response：

This loop is wrong:

for x in grr:
    for y in grr:
        print(grr)

You're basically printing grr over and over again. Probably you meant something like this:

for x in grr:
    print(x)