Python, Tk and OptionMenu: how to sort a drop down list?

Question

I want to make a drop down list with tk and OptionMenu. I want to show a string to the user ("10 us", "40 us"...) and return a number (0, 1,...) which is a parameter that I send to a variable. It works well, but it's not sorted. I want to sort the list like the variable "lst1".

It should be:

• 10 us
• 20 us
• 40 us

• 80 us

   lst1 = {"10 us": 0, "20 us": 1, "40 us": 2, "80 us": 3, "160 us": 4, "320 us": 5, "640 us": 6, "1.28 ms": 7, "2.56 ms": 8, "5.12 ms": 9, "10.24 ms": 10} var_tc = StringVar() var_tc.set("40 us") list_tc = OptionMenu(frame, var_tc, *lst1.keys()) list_tc.config(takefocus=1) list_tc.grid(row=10, column=1, padx=2, pady=10) param.tc = lst1[var_tc.get()] 

Could you help me, please? :)

Answer 1

The issue is that you're using a dictionary as a list, and dictionaries don't have any notion of order. Two ways you could do it; both are pretty straightforward.

Way 1: Just use sorted keys

You don't have to change much, just when you pass in lst1.keys() , you instead pass in sorted(lst1.keys()) , since keys() returns a list and you can give a sorted one of those.

Way 2: Use a dictionary that keeps order

One of the python standard libraries is collections , which contains many containers of varying usefulness. One of these is the OrderedDict , a dictionary that keeps the order in which you enter things. You would import it as from collections import OrderedDict , and initialize it as any other object - lst1 = OrderedDict([("10us",0), ("20us",1), ...])