Delete specific Values of an Array: Python

Question

I have an array of the shape (1179648, 909). The problem is that some rows are filled with 0's only. I am checking for this as follows:

for i in range(spectra1Only.shape[0]):
    for j in range(spectra1Only.shape[1]):
        if spectra1Only[i,j] == 0:

I now want to remove the whole row of [i] if there is any 0 appearing to get a smaller amount of only the data needed.

My question is: what would be the best method to do so? Remove? Del? numpy.delete? Or any other method?

The problem is that some rows are filled with 0's only and remove the whole row of [i] if there is any 0 appearing are contradictory. do you want to remove a row when even a single value is 0 or when all values are 0? — user8401765
– user8401765, Commented Nov 22, 2018 at 9:42
shouldnt make a difference as if there is one 0 the whole row will be 0 — Luke M.
– Luke M., Commented Nov 22, 2018 at 9:44

jpp · Accepted Answer · 2018-11-22 09:29:39Z

1

You can use Boolean indexing with np.any along axis=1:

spectra1Only = spectra1Only[~(spectra1Only == 0).any(1)]

Here's a demonstration:

A = np.random.randint(0, 9, (5, 5))

print(A)

[[5 0 3 3 7]
 [3 5 2 4 7]
 [6 8 8 1 6]
 [7 7 8 1 5]
 [8 4 3 0 3]]

print(A[~(A == 0).any(1)])

[[3 5 2 4 7]
 [6 8 8 1 6]
 [7 7 8 1 5]]

answered Nov 22, 2018 at 9:29

jpp

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1 Comment

Luke M. Over a year ago

wow thank you so much thats so much easier and totally solves what i needed! sorry but im a beginner and teaching things somehow by myself

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