Python 2D array assignment

Question

In Matlab I can assign values inside arrays as follows.

a = [];
a(end+1, 1:2) = [1,2];
a(end,3:4) = [3,4];
a(end+1, 1:2) = [5,6];
a(end,3:4) = [7,8];

and so on. But in Python I can use the append command to append an array to the existing array. e.g.

a = []
a.append([1,2,3,4])
a.append([5,6,7,8])

My problem is I should assign the first two values at some point and the next two values in some other point as shown in my Matlab code. How can I do that?

an example of your expected output would be good. the python code you are showing would produce a=[[1,2,3,4]], while it seems from the matlab code that you want a=[[1,2],[3,4]] — jaumebonet
– jaumebonet, Commented Mar 25, 2018 at 13:10
I don't think the matlab code does what you think it does. Every time you run the command a(end+1, ...) you extend a by one more row; you're not assigning the values to the columns. — dROOOze
– dROOOze, Commented Mar 25, 2018 at 13:15

hoyland · Accepted Answer · 2018-03-25 13:12:27Z

3

I think you're looking for extend:

a = []
a.append([1,2])  # [[1,2]]
a[-1].extend([3,4])  # [[1,2,3,4]]

answered Mar 25, 2018 at 13:12

hoyland

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