I am looking for a way to sort a list in order of appearance in another string, so that the the follow code
thelist = ["a", "b", "c"]
thestring = "b c a"
will be able to be sorted into
["b", "c", "a"]
as that is the order that each of the list objects appear in the string.
How would I go about achieving this? Would it be possible to use the sorted function with certain param to easily achieve this or something else? Thanks.
Turn your string into a map:
indices = {c: i for i, c in enumerate(thestring.split())}
then sort using that map:
sorted(thelist, key=indices.get)
This allows for values from thestring missing in thelist as well as vice-versa. This also works correctly for repeating elements in thelist.
Demo:
>>> thestring = "b c a"
>>> indices = {c: i for i, c in enumerate(thestring.split())}
>>> sorted(['a', 'b', 'c'], key=indices.get)
['b', 'c', 'a']
>>> sorted(['a', 'b', 'c', 'a', 'c', 'b'], key=indices.get)
['b', 'b', 'c', 'c', 'a', 'a']
>>> sorted(['a', 'a', 'a'], key=indices.get)
['a', 'a', 'a']
>>> sorted(['a', 'e', 'b'], key=indices.get)
['e', 'b', 'a']
{c: i for i, c in enumerate(thestring)}, the exact integer values don't really matter.
thestring.split(), instead of sortingthelist?.sort(key=lambda c: thestring.index(c)), but that won't deal with repeats nicelythelist? Or repeats inthestring? In which case what position wins?