CODEWITHSUNDEEP
pythonlisttuples
fizis
fizis

Reputation: 193

How to pair up a list of list with a list?

I have two lists:

xy = [[1,2],[3,4],[5,6]]
z = [1,3,5]

I want to merge them to get:

xyz = [[1,2,1],[3,4,3],[5,6,5]]

or

xyz = [(1,2,1),(3,4,3),(5,6,5)]

Here is how I achieve this:

for i,lst in enumerate(xy):
    lst.append(z[i])
xy

Is there any neater way to do it without using the for loop or something?

Upvotes: 0

Views: 54

Answers (4)

Delgan
Delgan

Reputation: 19677

If you are using Python 3.5+, you can make use of PEP 448: 

xyz = [(*a, b) for a, b in zip(xy, z)]

This also uses list comprehension and zip() to make it a simple one-liner.

If you do not want to use a for loop at all, there is actually a way using functional programming and map(), but this is probably not the best way to go (Python does not favor functional programming):

xyz = map(lambda a, b: a + [b], xy, z)

Upvotes: 5

dseuss
dseuss

Reputation: 1141

I would suggest list-comprehensions for readability:

[a + [b] for a, b in zip(xy, z)]

Upvotes: 0

RomanPerekhrest
RomanPerekhrest

Reputation: 92854

Short list comprehension with enumerate function:

result = [l+[z[k]] for k,l in enumerate(xy)]
print(result)

The output:

[[1, 2, 1], [3, 4, 3], [5, 6, 5]]

Upvotes: 0

ForceBru
ForceBru

Reputation: 44878

This may be a neater way:

Ret = [a + [b] for a, b in zip(xy, z)]

Upvotes: 3

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