Reorder elements in Erlang

Question

I want to redefine the order of a tuple looking for specific words

Example, I have a list of tuples like this:

[{"a",["r001"]},
 {"bi",["bidder"]},
 {"bo",["an"]}]

But sometimes the order of the tuples can change for example:

[{"bi",["bidder"]},
 {"a",["r001"]},
 {"bo",["an"]}]

or

[{"bo",["an"]},
 {"a",["r001"]},
 {"bi",["bidder"]}]

The first string/list of the tuple is my unique key ("bo","a","bi")

But I want to be able to reorder the list of tuples, always like:

 [{"a",["r001"]},
     {"bi",["bidder"]},
     {"bo",["an"]}]

How can I achieve this?

Answer 1

This will do it:

lists:sort(fun({A,_},{B,_}) -> A =< B end, List).

Or this, which will sort by the tuples second element after the first:

lists:sort(List).

I offer the second version, because without the custom sort function, it is faster for data like this.

Answer 2

If you need to sort by specified element, you just sort by specified element

lists:keysort(1, List).