Extracting a specific part of a 2d list Python

Asked Jun 24 '15 at 11:53

Active Jun 24 '15 at 11:53

Viewed 51 times

Say I have a 2d list like below for example:

x = [[31, 34], [32, 34], [33, 34], [31, 35], [33, 35], [31,36], [32, 36]]

And,

y = [[31, 34], [33, 34], [31, 36]]

They are list of pixel coordinates. Basically what I am trying to do is extract only the elements (coordinates) in the list x which are NOT present in list y.

Please suggest an efficient way to do this. As I will be using this for lots of data I am worried about the speed. Thanks.

Edit: There is no particular pattern in the element indexes. So, it might be a search based method but I am not sure.

asked Jun 24 '15 at 11:53

Omzep

Related: http://stackoverflow.com/q/30653705/572670 – amit Jun 24 '15 at 11:55
1

`new = [i for i in x if i not in y]` – Malik Brahimi Jun 24 '15 at 12:01
@MalikBrahimi Thanks a lot. – Omzep Jun 24 '15 at 12:05
1

@MalikBrahimi While simple and clean, this is a very inefficient way to achieve it, and may be an issue if the list grows. – amit Jun 24 '15 at 12:13

Extracting a specific part of a 2d list Python

0 Answers0