Combine 2 lists to make a pair of coordinates in a list

Question

I need to combine values in two lists(longitude/latitude), to get one combined list (not in tuple or string format) My simple for loop is not iterating correctly over the first list, it is using one value to match all values in the second list, before moving to the next value.

for a in location1:
    for b in location2:
        location3.append(a+b)
location3

I am getting this (one 'a' matching to all 'b's first) :

[[41.7770923949, -87.6060037796],
[41.7770923949, -87.6547753762],
[41.7770923949, -87.5716351762],

I want this matching the same sequence in both lists:

[41.7770923949, -87.6060037796],
[41.784575915, -87.6547753762],

Also, trying things with zip/map like this:

list(map(lambda X: (X[0],X[1]), list(zip(location1,location2))))

Gives me this not in the correct form (is there another way?):

[([41.7770923949], [-87.6060037796]),
([41.784575915], [-87.6547753762]),

What are the inputs (the contents of two lists)? – kiner_shah Nov 19 '21 at 06:41 — kiner_shah, Nov 19 '21 at 06:41
Also, does `[X[0], X[1]]` work instead? – kiner_shah Nov 19 '21 at 06:41 — kiner_shah, Nov 19 '21 at 06:41

score 1 · Answer 1 · answered Nov 19 '21 at 06:43

1

You need to use zip directly to iterate over the two lists, not with your lambda.

l1 = [ 2, 4, 6, 8 ]
l2 = [ 1, 3, 5, 7 ]

coord = []

for a, b in zip( l1, l2 ):
    coord.append( [ a, b ] )

print( coord )

By the way, your question is related to this one.

answered Nov 19 '21 at 06:43

Camille

56
3

right ,but still the zip gives this format: `[[[41.7770923949], [-87.6060037796]], [[41.784575915], [-87.6547753762]], [[41.7442798961], [-87.5716351762]], ` – Gazoo Nov 19 '21 at 08:01
Because your input is a list of lists of 1 element, like `[[41.7770923949], [41.784575915],...]`? You should have given the input lists so we could know it ;) then you can use `coord.append( [ a[0], b[0] ] )` instead. – Camille Nov 19 '21 at 09:23
Sorry. I posted the image, not sure where it went. thanks for explaining. – Gazoo Nov 19 '21 at 12:39

Soroosh Noorzad · Answer 2 · 2021-11-19T07:04:25.133

0

You don't need the second for in your code. I think your data structure is like this:

location1 = [[1], [2], [3]]
location2 = [[4], [5], [6]]

Then try this:

location3 = []
for i, _ in enumerate(location1):
    location3.append(location1[i]+location2[i])
print(location3)

Result:

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

edited Nov 19 '21 at 07:04

answered Nov 19 '21 at 06:47

Soroosh Noorzad

503
1
6
18

yes, correct output: `[[41.7770923949, -87.6060037796], [41.784575915, -87.6547753762], [41.7442798961, -87.5716351762],` – Gazoo Nov 19 '21 at 08:04
@Gazoo Was my answer wrong? If not, I will appreciate a vote up. It's good to vote up the answers which lead to the correct solution. TNX – Soroosh Noorzad Nov 19 '21 at 10:46
1

I did, but too new so it didn't do anything. – Gazoo Nov 19 '21 at 12:09

score 0 · Accepted Answer · answered Nov 19 '21 at 07:14

You need to show both variables location1 and location 2. Final solution will be depends on it.

case 1: Both variables are list of list then below solution is for you.

location1 = [[1], [2], [3]]
location2 = [[4], [5], [6]]
location3 = list(map(lambda coord: [coord[0][0],coord[1][0]], zip(location1,location2)))
print(location3)

case 2: both variables list of integers

location1 = [1, 2, 3]
location2 = [4, 5, 6]
location3 = list(map(lambda coord: list(coord), zip(location1,location2)))
print(location3)

yes, Case 1 was correct: `[[41.7770923949, -87.6060037796], [41.784575915, -87.6547753762], [41.7442798961, -87.5716351762]` — Gazoo, Nov 19 '21 at 08:11

Combine 2 lists to make a pair of coordinates in a list

3 Answers3