Check if numpy array has a normal shape

Question

How do I check if a numpy array has a regular shape.

In the example below x is a *2 by 3* matrix. However y is not regular in the sense that it can't be represented as a proper matrix.

Given that I have a numpy array, is there a method (preferably in-built) that I can use to check that the numpy array is an actual matrix

In [9]: import numpy as np                                                      

In [10]: x = np.array([[1,2,3],[4,5,6]])                                        

In [11]: x.shape                                                                
Out[11]: (2, 3)

In [12]: y = np.array([[1,2,3],[4,5]])                                          

In [13]: y.shape                                                                
Out[13]: (2,)

Divakar · Accepted Answer · 2019-08-30 14:30:42Z

2

Both are arrays and those are valid shapes. But, with normal, think you meant that each element has the same shape and length across it. For that, a better way would be to check for the datatype. For the variable length case, it would be object. So, we can check for that condition and call out accordingly. Hence, simply do -

def is_normal_arr(a): # a is input array to be tested
    return a.dtype is not np.dtype('object')

answered Aug 30, 2019 at 14:30

Divakar

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Péter Leéh · Accepted Answer · 2019-08-30 11:07:36Z

1

I think the .shape method is capable of checking it. If you input an array which can form a matrix it returns it's actual shape, (2, 3) in your case. If you input an incorrect matrix it returns something like (2,), which says something's wrong with the second dimension, so it can't form a matrix.

edited Aug 30, 2019 at 11:07

answered Aug 30, 2019 at 11:05

Péter Leéh

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2 Comments

Georgina Skibinski Over a year ago

replace "correct/incorrect array" with "correct/incorrect matrix". All of them are correct arrays ;)

Péter Leéh Over a year ago

Yes, true. Thank you

Rahul charan · Accepted Answer · 2019-08-30 11:19:02Z

0

Here y is a one-dimensional array and the size of y is 2. y contains 2 list values. AND x is our actual matrix in a proper format.

check the dimensions by y.ndim AND x.ndim.

answered Aug 30, 2019 at 11:19

Rahul charan

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