Question

If I have sublist A: [‘E’,’C’, ‘W’], what is the most pythonic way to order the sublist according to the order of master list M: [‘C’,’B’,’W’,’E’,’K’]

My solution is seems rather rudimentary. I am curious if there is a more ‘pythonic’ way to get the same result.

ORDER = ['C','B','W','E','K']
possibilities = ['E','C', 'W']
possibilities_in_order = []

for x in ORDER:
    if x in possibilities: possibilities_in_order.append(x)

Answer 1

>>> order = ['C','B','W','E','K']
>>> possibilities = ['E','C','W']
>>> possibilities_in_order = sorted(possibilities, key=order.index)
>>> possibilities_in_order
['C', 'W', 'E']

How this works: for each element in possibilities, order.index(element) is called, and the list is simply sorted by those respective positions.

More details: Built-in Functions → sorted.