If you have array = np.array([1,2,3,4]) and you have index = np.array([0,1,2]) and you want to remove the index elements in array, what's the best way to do this without looping?
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1 Answer
You use numpy.delete:
smaller_array = np.delete(array,index)
2 Comments
Jaime
+1 But for completeness, in this other question, @askewchan found out that building a boolean mask is faster than using
np.delete, i.e mask = np.ones(array.shape, dtype=np.bool); mask[index] = False; smaller_array = array[mask].
seberg
The speed difference should mostly vanish, as delete will be basically a shorthand for that in 1.8. and later (with some faster paths for smaller slices and single integers). Until a bit longer there are some differences for out of bound/negative or boolean indices though.