CODEWITHSUNDEEP
pythonlist
Todd
Todd

Reputation: 439

python: how to take out the first list within list from two different list-in-list and pair them up to make them as separate list

it was really difficult to explain this in one sentence when I wrote a title. So, I'll jump to an example right away.

list1=[[1],[2],[3]]
list2=[['abc'],['def'],['ghi']]

a_list=[]

for i,j in zip(list1,list2):
    a_list.append(i)
    a_list.append(j)
print (a_list)

Acutal output:
[[1], ['abc'], [2], ['def'], [3], ['ghi']]

The above code gives me the above output.
But what I want to get is the below output.

Expected output:
[[1,'abc'], [2,'def'], [3,'ghi']]

I tried using extend but I guess it's not a matter of using append or extend. I think I'm missing one tiny part but could someone help me out?

Upvotes: 0

Views: 75

Answers (4)

blhsing
blhsing

Reputation: 106891

You can join the sub-lists in a list comprehension instead:

[a + b for a, b in zip(list1, list2)]

or map the two lists to the list.__add__ method:

list(map(list.__add__, list1, list2))

Upvotes: 3

MrJuicyBacon
MrJuicyBacon

Reputation: 326

What you're doing is appending initial lists to the a_list, not the values. What you need to do instead is to concatenate them and then append to the result like that:

for i,j in zip(list1,list2):
    a_list.append(i + j)

Another solution would be to append a list that consists of the first items of each of the initial lists.

for i,j in zip(list1,list2):
    a_list.append([i[0], j[0]])

Upvotes: 2

Nerveless_child
Nerveless_child

Reputation: 1406

This should solve it.

for i, j in zip(list1,list2):
    a_list.append(i+j)

print (a_list)

[[1, 'abc'], [2, 'def'], [3, 'ghi']]

Upvotes: 1

Swagga Ting
Swagga Ting

Reputation: 602

You only need a single variable when iterating through zip:

In [17]: for i in zip(list1, list2):
    ...:     print(i)
    ...:
([1], ['abc'])
([2], ['def'])
([3], ['ghi'])

And then:

In [20]: for i in zip(list1, list2):
    ...:     a_list.append(i)
In [21]: a_list
Out[21]: [([1], ['abc']), ([2], ['def']), ([3], ['ghi'])]

Since you are pulling two elements at a time, you are actually separating the elements and canceling the zip operation.

Upvotes: 1

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