Access columns and rows of numpy.ndarray

Question

I currently struggling with extracting certain columns and rows from a matrix stored as a numpy.ndarray.

I have a list in which I've appended these numpy.ndarrays.

This list is stored in a variable named data

print data[0].shape

outputs this

(400, 288)

Which I've according to the documentation have understood being the matrix has 400 rows, and 288 columns.

How do I extract all the 288 seperately?

Example:

>> import numpy as np
>> data = np.random.rand(3,3)
>> print data

[[ 0.97522481  0.57583658  0.68582806]
 [ 0.88509883  0.22261933  0.84307038]
 [ 0.59397925  0.51592125  0.54346909]]

How do I print the columns separately of this 3x3 matrix, first being

[0.97522481 , 0.88509883, 0.59397925 ]

without outputting the others?

A short example describing the desired behavior would be helpful — Itay
– Itay, Commented Nov 12, 2016 at 18:58
Depending on the use case, you might not need to separate out the columns as you can simply slice - docs.scipy.org/doc/numpy/reference/… — Divakar
– Divakar, Commented Nov 12, 2016 at 18:58

Ilya V. Schurov · Accepted Answer · 2016-11-12 19:04:23Z

0

Is it what you are looking for?

import numpy as np
arr = np.array([[1, 2], 
                [3, 4], 
                [5, 6]])
print(arr.shape)
# (3, 2)
print(list(data.T))
# [array([1, 3, 5]), array([2, 4, 6])]

answered Nov 12, 2016 at 19:04

Ilya V. Schurov

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