Generating tuple from a list of items in Python

Question

I;m trying to generate a tuple list from a larger list. how do I do it in pythonic way?

c = ['A1','B1','C1','A2','B2','C2']

Output required is something like this:

c = [('A1','A2'),('B1','B2'),('C1','C2')]

I tried to iterate through the list and put a regex to match for mattern and then added that to a tuple but that doesn;t look convincing for me.. Any better way to handle this?

This is somewhat unclear. So the first element of each tuple is in the first half of the list and the second element in the second half? Or are you pairing based on the first letter? — slider, Dec 11 '18 at 17:50

score 1 · Answer 1 · answered Dec 11 '18 at 17:47

1

If the length is exactly the same, you can do this:

half = len(c) / 2
pairs = zip(c[:half], c[half:])

zip accepts two lists and returns a list of pairs. The slices refer to the first half of the list and the second half, respectively.

answered Dec 11 '18 at 17:47

asthasr

9,125
1
29
43

score 1 · Answer 2 · answered Dec 11 '18 at 17:47

1

You can slice the list at mid point and then zip with the list itself:

list(zip(c, c[len(c)//2:]))

answered Dec 11 '18 at 17:47

blhsing

91,368
6
71
106

score 0 · Accepted Answer · answered Dec 11 '18 at 17:48

With no assumption on ordering or size of each tuple, you can use collections.defaultdict. This does assume your letters are in range A-Z.

from collections import defaultdict

dd = defaultdict(list)

c = ['A1','B1','C1','A2','B2','C2']

for i in c:
    dd[i[:1]].append(i)

res = list(map(tuple, dd.values()))

print(res)

[('A1', 'A2'), ('B1', 'B2'), ('C1', 'C2')]

Generating tuple from a list of items in Python

3 Answers3