How to get list from list of list of tuples in python

Question

I have a list of list of tuples:

[[(1,0.99), (2,0.95)], [(2,0.97),(3,0.89),(1, 0.80)]]

From the above data how can I get the list of list such as:

[[1,2],[2,3,1]]

Answer 1

You can simply use a nested list comprehension :

lst = [[(1,0.99), (2,0.95)], [(2,0.97),(3,0.89),(1, 0.80)]]

r = [[i for i, _ in l] for l in lst]
print(r)
# [[1, 2], [2, 3, 1]]

Answer 2

similar using nested list comprehension with a little variance from @Moses Koledoye answer

lst = [[(1,0.99), (2,0.95)], [(2,0.97),(3,0.89),(1, 0.80)]]
result = [[i[0] for i in j] for j in lst]
# result = [[1, 2], [2, 3, 1]]

Answer 3

You can do this with groupby from the itertools module:

import itertools

L = [[(1,0.99), (2,0.95)], [(2,0.97),(3,0.89),(1, 0.80)]]

print [[x[0] for x in k] for k, g in itertools.groupby(L)]

Answer 4

Another option is to use a more functional approach. Use operator.itemgetter to construct a callable object that fetches the initial item from a collection, and apply it to each row of the main list using map .

from operator import itemgetter

lst = [[(1,0.99), (2,0.95)], [(2,0.97),(3,0.89),(1, 0.80)]]

ig0 = itemgetter(0)
print([list(map(ig0, row)) for row in lst])

output

[[1, 2], [2, 3, 1]]