Explicitly select items from a list or tuple

user_366309 0
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I have the following Python list (can also be a tuple):

myList = ['foo', 'bar', 'baz', 'quux']

I can say

>>> myList[0:3]
['foo', 'bar', 'baz']
>>> myList[::2]
['foo', 'baz']
>>> myList[1::2]
['bar', 'quux']

How do I explicitly pick out items whose indices have no specific patterns? For example, I want to select [0,2,3]. Or from a very big list of 1000 items, I want to select [87, 342, 217, 998, 500]. Is there some Python syntax that does that? Something that looks like:

>>> myBigList[87, 342, 217, 998, 500]
tuples indexing select list python
9 Answers

Another possible solution:

sek=[]
L=[1,2,3,4,5,6,7,8,9,0]
for i in [2, 4, 7, 0, 3]:
   a=[L[i]]
   sek=sek+a
print (sek)
user_89639610

like often when you have a boolean numpy array like mask

[mylist[i] for i in np.arange(len(mask), dtype=int)[mask]]

A lambda that works for any sequence or np.array:

subseq = lambda myseq, mask : [myseq[i] for i in np.arange(len(mask), dtype=int)[mask]]

newseq = subseq(myseq, mask)

user_44022670

Here is a one line lambda:

list(map(lambda x: mylist[x],indices))

where:

mylist=['a','b','c','d','e','f','g','h','i','j']
indices = [3, 5, 0, 2, 6]

output:

['d', 'f', 'a', 'c', 'g']
user_60443120
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