Getting a sublist of a Python list, with the given indices?

Question

I have a Python list, say a = [0,1,2,3,4,5,6]. I also have a list of indices, say b = [0,2,4,5]. How can I get the list of elements of a

Answer 1

A bit of speed comparison for all mentioned methods and others from Python dictionary: Get list of values for list of keys:

Python 2.7.11 |Anaconda 2.4.1 (64-bit)| (default, Jan 19 2016, 12:08:31) [MSC v.1500 64 bit (AMD64)] on win32

In[2]: import numpy.random as nprnd
idx = nprnd.randint(1000, size=10000)
l = nprnd.rand(1000).tolist()
from operator import itemgetter
import operator
f = operator.itemgetter(*idx)
%timeit f(l)
%timeit list(itemgetter(*idx)(l))
%timeit [l[_] for _ in idx]  # list comprehension
%timeit map(l.__getitem__, idx)
%timeit list(l[_] for _ in idx)  # a generator expression passed to a list constructor.
%timeit map(lambda _: l[_], idx)  # using 'map'
%timeit [x for i, x in enumerate(l) if i in idx]
%timeit filter(lambda x: l.index(x) in idx, l)  # UPDATE @Kundor: work only for list with unique elements
10000 loops, best of 3: 175 µs per loop
1000 loops, best of 3: 707 µs per loop
1000 loops, best of 3: 978 µs per loop
1000 loops, best of 3: 1.03 ms per loop
1000 loops, best of 3: 1.18 ms per loop
1000 loops, best of 3: 1.86 ms per loop
100 loops, best of 3: 12.3 ms per loop
10 loops, best of 3: 21.2 ms per loop

So the fastest is f = operator.itemgetter(*idx); f(l)