7

Similar to this, I am curious how to remove specific elements from every numpy array in a numpy array. My data is given in form of X below. I think this should work:

X = [[x1 x2 ... xn] [x1 x2 ... xn] ... [x1 x2 ... xn]]
X.shape
(n,|x|)

Y=numpy.delete(X[:],1)

I would think that Y should now be:

Y = [[x1 x3 ... xn] [x1 x3 ... xn] ... [x1 x3 ... xn]]

where Y.shape should equal (n-1,|y|=|x|), but it is not. What am I failing to grasp? My intention is to be able to remove all x2's (low correlation variable) in every array in X in order to send to a decision tree regressor. It would be even better if I could do this:

index = [ 1 3 7]
Y=numpy.delete(X[:],index)

which works if X is not a 'nested' numpy array. refer to response in link for:

array([1, 2, 3, 4, 5, 6, 7, 8, 9])

index
[2, 3, 6]

new_a = np.delete(a, index)

new_a
array([1, 2, 5, 6, 8, 9])
Improve this question

1 Answer 1

Reset to default
9

You need to apply np.delete along an axis. Please refer to the third example in the documentation.

Y = np.delete(X, 1, axis=1)
Improve this answer
Sign up to request clarification or add additional context in comments.

3 Comments

Sweet! To ensure I understand the idea of axis. If my example was an array in an array in an array, then would I declare axis=2?
downwards across rows (axis 0), horizontally across columns (axis 1).
In numpy we talk about multidimensional arrays, i.e. 2D or 3D arrays. They can be converted into lists of lists (of lists). But 'arrays of arrays' is distinct, which arises only if the inner arrays vary in size (i.e. ragged arrays).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.