Selecting columns from multi-dimensional numpy array

Question

I created a multi-dimensional numpy array using this code:

pt=[[0 for j in range(intervals+1)] for i in range(users+1)]

A `print (np.shape(pt)) gives me

(1001,169)

I then proceeded to populate the array (code not shown) before trying to select everything but the first column to feed into matplotlib.

I referred to posts on how to select columns from a multi-dimensional array: here here and here

all of whom say I should do:

pt[:,1:]

to select everything but the first column. However this gives me the error message:

TypeError: list indices must be integers or slices, not tuple

Why not simply numpy.zeros((users + 1, intervals + 1), dtype=int)? — Nils Werner
– Nils Werner, Commented Jun 14, 2017 at 10:08
@Markus - You are absolutely correct. I just realized this. People like this (i-programmer.info/programming/python/…) are to blame. For goodness sake don't say "For a programmer moving to Python the problem is that there are no explicit provisions for multidimensional arrays. As a list can contain any type of data there is no need to create a special two-dimensional data structure. All you have to do is store lists within lists". — Reddspark
– Reddspark, Commented Jun 14, 2017 at 10:13

Reddspark · Accepted Answer · 2017-06-14 10:14:13Z

0

Anyone else that reaches this post from having made the same mistake (see comments above), if you want to continue using lists then do pt[:][0:1] but really I recommend switching to numpy and ignoring all the results you get when you search for 'declaring python array'

answered Jun 14, 2017 at 10:14

Reddspark

7,63712 gold badges57 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Selecting columns from multi-dimensional numpy array

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related