[Python] Redirecting output of a "for" loop into two-dimensional lists

Hi guys,

i'm quite new at Python scripting, asking your help.

I've got a loop in a loop (two consecutive "for" loop).

Is there a way to create a two dimensional list (whose number of item (list) is the count of the first loop variable).

I'm thinking to something like

list = [list1,list2,list3,...,listN] #where N is the number of cicle in the first loop

list1 is the result of cicle in the second loop (caused by the second variable), like list 2m list3, and so on till to listN..

I've tried like this, but it doesn't work:

MainList = []
SubList = []

for i in range(len(InputList_1)):
MainList.append(SubList)
for j in range(len(InputList_2)):
MainList[i].append(rs.TransformObject(InputList_1[i],XformMatrix[j]))

it retrieves this error:

Runtime error (ArgumentTypeException): __getitem__() takes exactly 2 arguments (1 given)

Replies to This Discussion

Permalink Reply by Eduardo on October 28, 2014 at 9:59am

The concept is to create in grasshopper one branch each sublist, but avoiding gh data structure, and creating it in python.

Permalink Reply by Anders Holden Deleuran on October 28, 2014 at 11:37am

Do you mean making a nested list using two for for loops? If so you can try something like this..

Permalink Reply by GM on October 28, 2014 at 12:08pm

It's almost like that.

I've updated the code, and it works now, but not at all.
It creates too much lists.

This is the code

MainList = []
SubList = []
for i in range(len(InputList_1)):
    for j in range(len(InputList_2)):
        SubList.append(rs.TransformObject(InputList_1[i],MirrorMatrix_L[j],True))
        MainList.append(SubList)

I've just culled the [i] from the last .append

The real problem is that it copies the both the two list j times. Here is a screenshot

Permalink Reply by GM on October 28, 2014 at 12:10pm

2 Different Lists (in different branch) 6 times, for totally 12 branches.

Permalink Reply by Eduardo on October 28, 2014 at 12:13pm

Thanks for the reply.
I tried both ways and it doesn't work...

Something else?

Permalink Reply by Eduardo on October 28, 2014 at 1:14pm

It has been quite easy to extract the right values in a flat python list.
And i've found a way to post-create sublists as temporary way, but still looking for a cleaner way =)

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