Let's say I have a list of elements X and one of indices Y.
X = [1, 2, 3, 4, 5, 6, 7]
Y = [0, 3, 4]
Is there a function in Python that allows one to extract elements from X based on the indices provided in Y? After execution, X would be:
X = [1, 4, 5]
X = [X[index] for index in Y]
This is a list comprehension; you can look up that topic to learn more.
The list comprehension provided by @Prune is the way to go in pure python. If you don't mind numpy, it might be easier just use their indexing scheme:
import numpy as np
>>> np.array(X)[Y]
array([1, 4, 5])
You can use list.__getitem__ with map:
X = [1, 2, 3, 4, 5, 6, 7]
Y = [0, 3, 4]
res = list(map(X.__getitem__, Y)) # [1, 4, 5]
Or, if you are happy to use a 3rd party library, you can use NumPy:
import numpy as np
X = np.array([1, 2, 3, 4, 5, 6, 7])
res = X[Y] # array([1, 4, 5])
