Sorting sub-lists into new sub-lists based on common first items

Question

I have a large number of two-membered sub-lists that are members of a list called mylist:

mylist = [[\'AB001\', 22100],
          [\'AB001\', 32         


        

Answer 1

Without importing any packages:

• Build a dictionary and then get the values to a list
  • Use .get to determine if a key exists, and return some specified value, None in this case, if the key is nonexistent.
  • dict.get defaults to None, so this method never raises a KeyError.
    • If None is a value in the dictionary, then change the default value returned by .get.
      • test.get(t[0], 'something here')
• Because: sub-lists based on common first items.
  • Add index 0 as the key, and then add the list, t, as the dict value.

test = dict()
for t in mylist:
    if test.get(t[0]) == None:
        test[t[0]] = [t]
    else:
        test[t[0]].append(t)
        
final = list(test.values())

# print final results in

[[['AB001', 22100], ['AB001', 32935], ['AB001', 34439]],
 [['XC013', 99834], ['XC013', 86701]],
 [['VD126', 18884]]]