python – Sorting list based on values from another list

python – Sorting list based on values from another list

Shortest Code

[x for _, x in sorted(zip(Y, X))]

Example:

X = [a, b, c, d, e, f, g, h, i]
Y = [ 0,   1,   1,    0,   1,   2,   2,   0,   1]

Z = [x for _,x in sorted(zip(Y,X))]
print(Z)  # [a, d, h, b, c, e, i, f, g]

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Generally Speaking

[x for _, x in sorted(zip(Y, X), key=lambda pair: pair[0])]

Explained:

1. zip the two lists.
2. create a new, sorted list based on the zip using sorted().
3. using a list comprehension extract the first elements of each pair from the sorted, zipped list.

For more information on how to setuse the key parameter as well as the sorted function in general, take a look at this.

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Zip the two lists together, sort it, then take the parts you want:

>>> yx = zip(Y, X)
>>> yx
[(0, a), (1, b), (1, c), (0, d), (1, e), (2, f), (2, g), (0, h), (1, i)]
>>> yx.sort()
>>> yx
[(0, a), (0, d), (0, h), (1, b), (1, c), (1, e), (1, i), (2, f), (2, g)]
>>> x_sorted = [x for y, x in yx]
>>> x_sorted
[a, d, h, b, c, e, i, f, g]

Combine these together to get:

[x for y, x in sorted(zip(Y, X))]

python – Sorting list based on values from another list

Also, if you dont mind using numpy arrays (or in fact already are dealing with numpy arrays…), here is another nice solution:

people = [Jim, Pam, Micheal, Dwight]
ages = [27, 25, 4, 9]

import numpy
people = numpy.array(people)
ages = numpy.array(ages)
inds = ages.argsort()
sortedPeople = people[inds]

I found it here:
http://scienceoss.com/sort-one-list-by-another-list/