How can we have SortedList as a parameter in SortedDict in Python?

Question

I am trying to use SortedList from sortedcontainers library as a parameter for SortedDict. Even though the Initialization maps = SortedDict(SortedList()) worked. I am Unable to insert any data into the SortedDict maps

from sortedcontainers import SortedDict, SortedList
maps = SortedDict(SortedList)
maps[1] = [1,2] 

I tried doing the above code but i got a TypeError:Int object is not Iterable so i tried maps['a'] = [1,2] and it worked but I am unable to further add elements into maps['a'] using .add() or .update() methods of SortedList.

I am only able to do so using .append() method => maps['a'].append(0) does work but it loses the functionality of SortedList as I got maps = {'a':[1,2,0]} where list was unsorted.

So how can I get maps = {1:[1,2,4], 2:[8,9], 3:[1,5,6]} in this way.

I have also tried using maps = SortedDict(lambda x:SortedList) which worked for defaultdict, so I tried it here but it didn't work.

Answer 1

You are passing the class SortedList to the constructor of the SortedDict. What do you expect that to do?

The documentation explains what it actually does:

Optional key-function argument defines a callable that, like the key argument to the built-in sorted function, extracts a comparison key from each dictionary key. If no function is specified, the default compares the dictionary keys directly. The key-function argument must be provided as a positional argument and must come before all other arguments.

So when trying to insert an entry, SortedDict calls SortedList(1). This throws an error because the SortedList constructor expects an iterable, but 1 is not iterable.

If you want a SortedDict whose values are SortedList objects, just create an empty SortedDict and put only SortedList objects into it:

maps = SortedDict()
maps[1] = SortedList([1, 2])