How can I get the list slice using a list of indexes in Python?

Question

In Perl I can easily select multiple array elements using a list of indexes, e.g.

my @array = 1..11;
my @indexes = (0,3,10);
print "@array[ @indexes ]"; # 1 4 11

What's the canonical way to do this in Python?

Jon Clements · Accepted Answer · 2013-06-15 17:15:44Z

7

use operator.itemgetter:

from operator import itemgetter
array = range(1, 12)
indices = itemgetter(0, 3, 10)
print indices(array)
# (1, 4, 11)

Then present that tuple however you want..., eg:

print ' '.join(map(str, indices(array)))
# 1 4 11

answered Jun 15, 2013 at 17:15

Jon Clements

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2 Comments

wow!! Thanks. From where you get to know all these techniques:)

@rajpy It's worth taking the time (although not all in one sitting) to read through the library reference to see what is there.

falsetru · Accepted Answer · 2013-06-15 17:27:03Z

4

>>> array = range(1, 12)
>>> indexes = [0, 3, 10]
>>> [array[i] for i in indexes]
[1, 4, 11]
>>>
>>> list(map(array.__getitem__, indexes))
[1, 4, 11]

answered Jun 15, 2013 at 17:19

falsetru

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Ashwini Chaudhary · Accepted Answer · 2013-06-15 17:35:25Z

1

>>> import numpy as np
>>> indexes = (0,3,10)
>>> x = np.arange(1,12)
>>> x [np.array(indexes)]
array([ 1,  4, 11])

answered Jun 15, 2013 at 17:35

Ashwini Chaudhary

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