How do I obtain the index list in a NumPy Array of all the NaN values present using Python

Question

Hi all, pretty simple question but I am held back.

Let us consider the case where I have created a NumPy array which is valid. 

Consider the example:

[[1,2,3,4],
[2,3,NaN,5],
[NaN,5,2,3]]

And now, let us say that I want to be presented with a certain list that consists of all of the index values of the missing elements. In this case, the missing elements is [(1,2),(2,0)] as you can see.

How can I go about doing this? 

Appreciate all the help!

Answer 1

Hi, it is pretty simple, to be honest. Check this out:

You will have to make use of np.isnan along with no.argwhere to achieve what you desire in this question.

The following code will help give you some clarity:

x = np.array([[1,2,3,4],
              [2,3,np.nan,5],
              [np.nan,5,2,3]])
np.argwhere(np.isnan(x))

The output for the above code is as follows:

array([[1, 2],
      [2, 0]])

I am sure this helped to answer your query, cheers!

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Thanks!