Question

Hello I am trying to figure out how to sort a nested list by multiple variables while some will not be sorted by 1,2,3 and instead by a predetermined list.

For Example:

List=[[XD,1],[XD,3],[XD,2],[X5,2],[X5,3],[XT,2]]

This would result in:

[[XD,1],[XD,2],[XD,3],[XT,2],[X5,2],[X5,3]]

The first element would be sorted by the sortbylist and the second element simply in numerical order.

SortByList={'XD': 'A', 'XT':'B', 'XQ': 'C','X5': 'D'}

I have currently been trying to use the code:

List.sort(key=SortByList.__getitem__  x: x[0])
List=sorted(List,key=itemgetter(1))

This however does not seem to work. Any hints?

One of the easiest ways to do this is:

Result=sorted(List, key=lambda x:(SortByList[x[0]],x[1]))

Answer 1

How about:

In [2]: List=[['XD',1],['XD',3],['XD',2],['X5',2],['X5',3],['XT',2]]

In [3]: SortByList={'XD': 'A', 'XT':'B', 'XQ': 'C','X5': 'D'}

In [4]: sorted(List, key=lambda x:(SortByList[x[0]],x[1]))
Out[4]: [['XD', 1], ['XD', 2], ['XD', 3], ['XT', 2], ['X5', 2], ['X5', 3]]

This uses a two-element compound key as explained in your question.