CODEWITHSUNDEEP
python
Nitesh
Nitesh

Reputation: 77

Iterate function over all the items in the list

Consider a list with various points

l=[(point1,point2),(point3,point4),....,(point 2n-1, point 2n)]

now we have a function that calculates the distance between point 

distance(point1,point2)

How to apply the function for all the points in the list?

Upvotes: 1

Views: 58

Answers (3)

kederrac
kederrac

Reputation: 17322

you can use a simple for loop:

result = []

for p1, p2 in l:
    result.append(distance(p1,p2))

Upvotes: 0

user2390182
user2390182

Reputation: 73450

You can use itertools.starmap:

from itertools import starmap

list(starmap(distance, l))

or just a list comprehension:

[distance(*p) for p in l]  # hence the name `starmap`

if you are in fact looking for the distances of any pair of points (coordinate pairs), you can use itertools.product:

from itertools import starmap, product

list(starmap(distance, product(l, repeat=2)))
# or
[distance(*points) for points in product(l, repeat=2)]

If you don't want to pair points with themselves and don't care about order (after all, "distance" indicates symmetry), use combinations:

from itertools import starmap, combinations

list(starmap(distance, combinations(l, 2)))

Upvotes: 4

Vishnudev Krishnadas
Vishnudev Krishnadas

Reputation: 10960

Zip with a sliced list and use list comprehension

distances = [distance(p1, p2) for p1, p2 in list(zip(l, l[1:]))]

What does list(zip(l, l[1:])) do? It combines two adjacent elements

>>> l = [(0,1), (1,2), (2,3), (3,4)]
>>> list(zip(l, l[1:]))
[((0, 1), (1, 2)), ((1, 2), (2, 3)), ((2, 3), (3, 4))]

Upvotes: 0

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