python iteration through list of list [duplicate]

Question

I have list a with below elements :

[[('433318', 0.7064461851335214), ('433363', 0.6709502341952089)],
 [('433395', 0.6988424611161282), ('433400', 0.6794787567547861)],
 [('433395', 0.6871546406771576), ('433363', 0.653218445986381)]]

Now I wanted retrieve the elements into a new list b which will have

['433318','433363','433395','433400','433395','433363']

a[0][0][0] gives ‘433318’
a[0][1][0] gives ‘433363’

But I am looking for a generic way (may be in a loop which iterates through the entire list) and gives me the desired result ?

Possible duplicate of Creating a Python list from a list of tuples and a metric ton of other, related questions and solutions provided on SO... — Patrick Artner
– Patrick Artner, Commented Apr 9, 2019 at 6:32

Ocaso Protal · Accepted Answer · 2019-04-09 06:26:10Z

3

Use a list comprehension:

l = [[('433318', 0.7064461851335214), ('433363', 0.6709502341952089)],
[('433395', 0.6988424611161282), ('433400', 0.6794787567547861)],
[('433395', 0.6871546406771576), ('433363', 0.653218445986381)]]

[y[0] for x in l for y in x]

answered Apr 9, 2019 at 6:26

Ocaso Protal

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Comments

theberzi · Accepted Answer · 2019-04-09 06:30:55Z

2

Using a list comprehension is best, but it may be helpful to see how a regular loop version would look like:

my_list = [[('433318', 0.7064461851335214), ('433363', 0.6709502341952089)],
[('433395', 0.6988424611161282), ('433400', 0.6794787567547861)],
[('433395', 0.6871546406771576), ('433363', 0.653218445986381)]]

result = []
for inner_list in my_list:
    for inner_tuple in inner_list:
        result.append(inner_tuple[0])

answered Apr 9, 2019 at 6:30

theberzi

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1 Comment

pyds_learner Over a year ago

Thanks Federico to this loop explanation.

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