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Iterating over two list of lists, getting the same element of each inner list

June 28, 2022

I am working with ETABS API using python. So there is a command like:

SapModel.FrameObj.AddByCoord(x1,y1,z1,x2,y2,z2,"name","section")

where x1 , x2 ,etc are coordinates in Cartesian coordinate system.
I have two separate lists that each one consist of 5 sub lists and each sub list contain 5 elements that are X and Y coordinates of different points. Some thing like:

X=[[2,4,5,9,10],[3,6,7,9,11],[10,16,17,19,20],[8,9,15,16,20],[3,12,14,18,21]]
Y=[[0,5,6,8,10],[1,3,7,8,16],[10,13,14,18,23],[6,8,11,14,16],[5,14,15,19,20]]

The output I’m looking for is:

for i in range(3,16,3):
    SapModel.FrameObj.AddByCoord(X[0][0],Y[0][0],i,X[1][0],Y[1][0],i,"name","section")
    SapModel.FrameObj.AddByCoord(X[1][0],Y[1][0],i,X[2][0],Y[2][0],i,"name","section")
    SapModel.FrameObj.AddByCoord(X[2][0],Y[2][0],i,X[3][0],Y[3][0],i,"name","section")
    SapModel.FrameObj.AddByCoord(X[3][0],Y[3][0],i,X[4][0],Y[4][0],i,"name","section")
    
    SapModel.FrameObj.AddByCoord(X[0][1],Y[0][1],i,X[1][1],Y[1][1],i,"name","section")
    SapModel.FrameObj.AddByCoord(X[1][1],Y[1][1],i,X[2][1],Y[2][1],i,"name","section")
    SapModel.FrameObj.AddByCoord(X[2][1],Y[2][1],i,X[3][1],Y[3][1],i,"name","section")
    ...
    ...
    ...
    SapModel.FrameObj.AddByCoord(X[0][4],Y[0][4],i,X[1][4],Y[1][4],i,"name","section")
    SapModel.FrameObj.AddByCoord(X[1][4],Y[1][4],i,X[2][4],Y[2][4],i,"name","section")
    SapModel.FrameObj.AddByCoord(X[2][4],Y[2][4],i,X[3][4],Y[3][4],i,"name","section")
    SapModel.FrameObj.AddByCoord(X[3][4],Y[3][4],i,X[4][4],Y[4][4],i,"name","section")

I have no idea how to do that. Can you help me with that?

>Solution :

You can iterate as follows

for _x, _xs, _y, _ys in zip(X,Y,X[1:],Y[1:]):
    for x, y, xs, ys in zip(_x, _xs, _y, _ys):
        print(x, y, xs, ys)

for _x, _xs, _y, _ys in zip(zip(*X), zip(*Y) , zip(*X[1:]), zip(*Y[1:])):
    for x, y, xs, ys in zip(_x, _xs, _y, _ys):
        print(x, y, xs, ys)

The second way would produce 4-pairs in the exact order as in your example:

2 0 3 1
3 1 10 10
10 10 8 6
8 6 3 5
4 5 6 3
6 3 16 13
16 13 9 8
9 8 12 14
5 6 7 7
7 7 17 14
17 14 15 11
15 11 14 15
9 8 9 8
9 8 19 18
19 18 16 14
16 14 18 19
10 10 11 16
11 16 20 23
20 23 20 16
20 16 21 20