How to get the indices list of all NaN value in numpy array

Question

Say now I have a numpy array which is defined as     1 2 3 4    2 3 NaN 5    NaN 5 2 3     Now I want to have a list that contains all the indices of the missing values  which is   1 2   2 0   at this case   Is there any way I can do that

User · Answer

You can use np where to match the boolean conditions corresponding to Nan values of the array and map each outcome to generate a list of tuples    gt  gt  gt list map tuple  np where np isnan x       1  2    2  0

User · Answer

Since x  x returns the same boolean array with np isnan x   because np nan  np nan would return True   you could also write    np argwhere x  x    However  I still recommend writing np argwhere np isnan x   since it is more readable  I just try to provide another way to write the code in this answer

User · Answer

np isnan combined with np argwhere  x   np array   1 2 3 4                  2 3 np nan 5                  np nan 5 2 3    np argwhere np isnan x     output   array   1  2           2  0

[python] How to get the indices list of all NaN value in numpy array?

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