sorting multiple lists based on a single list in python

Question

I'm printing a few lists but the values are not sorted.

for f, h, u, ue, b, be, p, pe, m, me in zip(filename, human_rating, rating_unigram, percentage_error_unigram, rating_bigram, percentage_error_bigram, rating_pos, percentage_error_pos, machine_rating, percentage_error_machine_rating):
        print "{:>6s}{:>5.1f}{:>7.2f}{:>8.2f} {:>7.2f} {:>7.2f}  {:>7.2f} {:>8.2f}  {:>7.2f} {:>8.2f}".format(f,h,u,ue,b,be,p,pe,m,me)

What's the best way to sort all of these lists based on the values in 'filename'?

So if:

filename = ['f3','f1','f2']
human_rating = ['1','2','3']
etc.

Then sorting would return:

filename = ['f1','f2','f3']
human_rating = ['2','3','1']
etc.

David Wolever · Accepted Answer · 2012-07-22 16:29:52Z

24

I would zip then sort:

zipped = zip(filename, human_rating, …)
zipped.sort()
for row in zipped:
     print "{:>6s}{:>5.1f}…".format(*row)

If you really want to get the individual lists back, I would sort them as above, then unzip them:

filename, human_rating, … = zip(*zipped)

answered Jul 22, 2012 at 16:29

David Wolever

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3 Comments

Bart Römgens Over a year ago

Python 3 note: zip returns an iterator in Python 3, use list to see its content, zipped = list(zip(filename, human_rating, …))

Reegan Miranda Over a year ago

@David Wolever very nice solution.

mrazizi Over a year ago

In case you're getting 'zip' object has no attribute 'sort' error, use sorted(zipped) as @jochen-ritzel mentioned in his answer.

orip · Accepted Answer · 2012-07-22 16:33:57Z

12

How about this: zip into a list of tuples, sort the list of tuples, then "unzip"?

l = zip(filename, human_rating, ...)
l.sort()
# 'unzip'
filename, human_rating ... = zip(*l)

Or in one line:

filename, human_rating, ... = zip(*sorted(zip(filename, human_rating, ...)))

Sample run:

foo = ["c", "b", "a"]
bar = [1, 2, 3]
foo, bar = zip(*sorted(zip(foo, bar)))
print foo, "|", bar # prints ('a', 'b', 'c') | (3, 2, 1)

answered Jul 22, 2012 at 16:33

orip

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2 Comments

Parisa Khateri Over a year ago

Nice and compact solution! the problem is that it returns tuples not lists.

matheburg Over a year ago

@ParisaKhateri Combine it with map if you need lists: l1, l2, l3, ... = map(list, zip(*sorted(zip(l1, l2, l3, ...))))

Jochen Ritzel · Accepted Answer · 2012-07-22 16:32:03Z

2

zip returns a list of tuples which you can sort by their first value. So:

for ... in sorted(zip( ... )):
    print " ... "

answered Jul 22, 2012 at 16:32

Jochen Ritzel

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