Given
mylist = ["a", "b", "c"]
how can I subset elements 0 and 2 (i.e., ["a", "c"])?
4 Answers
Although this is not the usual way to use itemgetter,
>>> from operator import itemgetter
>>> mylist = ["a", "b", "c"]
>>> itemgetter(0,2)(mylist)
('a', 'c')
If the indices are already in a list - use * to unpack it
>>> itemgetter(*[0,2])(mylist)
('a', 'c')
You an also use a list comprehension
>>> [mylist[idx] for idx in [0,2]]
['a', 'c']
or use map
>>> map(mylist.__getitem__, [0,2])
['a', 'c']
7 Comments
John La Rooy
@Franklin,
map is still a solid part of Python. It's still a builtin in Python3 and has even been improved to return an iterator instead of a list.
Utku Zihnioglu
Franklin, why don't you read this question? You might see when and why someone might use map instead of list comprehension.
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For fancy indexing you can use numpy arrays.
>>> mylist = ["a", "b", "c"]
>>> import numpy
>>> myarray = numpy.array(mylist)
>>> myarray
array(['a', 'b', 'c'],
dtype='|S1')
>>> myarray[[0,2]]
array(['a', 'c'],
dtype='|S1')
1 Comment
John La Rooy
@Mark, If answer is perfect for you, you should mark it as accepted. to do that, simply click on the tick outline.
Here's one solution (among many):
[mylist[i] for i in [0, 2]]
Comments
If you want every second one, mylist[::2].
[mylist[0], mylist[1]]? So please describe what do you really want to do.