How to find row number and column number of a specific element in a multi dimensional array created with numpy?

Question

In a multi-dimensional array created using numpy in python like

matrix=np.array[[0,0,0,0,0], [0,0,0,0,1], [0,0,0,0,0], [0,0,0,0,0], [0,0,0,0,0]]

if we were to treat it as matrix. Is there any way to find the row number and column number of element '1' or any other specific element inside the matrix?

Use np.where() ,

Rahul Vishwakarma
– Rahul Vishwakarma

2020-08-02 09:30:55 +00:00
Commented Aug 2, 2020 at 9:30 — Rahul Vishwakarma
– Rahul Vishwakarma, Commented Aug 2, 2020 at 9:30

Valdi_Bo · Accepted Answer · 2020-08-02 10:38:19Z

3

One of possible solutions is to use np.argwhere:

np.argwhere(matrix == 1)

but note that your array can contain multiple elements with just this value, so it returns a 2-D array, where each row contains indices of each element found.

If you want only the first such element, run:

np.argwhere(matrix == 1)[0]

This time you will get a 1-D array, containing 2 element (row and column number).

answered Aug 2, 2020 at 10:38

Valdi_Bo

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1 Comment

SSPlusUltra Over a year ago

thanks for the suggestion btw, i improved it a bit like if u do np.where(matrix==1) the output will be in tuples and we can retrieve both values of row and column by tuple unpacking res=np.where(matrix==1) and (a,b)=res then we can use 'a' and 'b' individually

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