Arranging items of a list in proper order-CodePudding

i want to arrange some items of my list in a following order.

raw_list = ['L1', 'L2', 'J1', 'L10', 'L12', 'J10', 'P2', 'P5', 'P11' ]

i want it to order it as L(ascending_integer), J(ascending_interger) and P(ascending_integer).

like as follows,

arranged_list = [
    'L1', 'L2', 'L10', 'L12',
    'J1', 'J10',
    'P1', 'P5', 'P11'
]

how can i do it?

CodePudding user response：

You can pass a key function to list.sort or sorted:

raw_list = ['L1', 'L2', 'J1', 'L10', 'L12', 'J10', 'P2', 'P5', 'P11']
arranged_list = sorted(raw_list, key=lambda x: ('LJP'.index(x[0]), int(x[1:])))
# ['L1', 'L2', 'L10', 'L12', 'J1', 'J10', 'P2', 'P5', 'P11']

This will raise a ValueError if a string starts with a letter other than L, J, or P.

raw_list = ['L1', 'L2', 'J1', 'L10', 'L12', 'J10', 'P2', 'P5', 'X11']
arranged_list = sorted(raw_list, key=lambda x: ('LJP'.index(x[0]), int(x[1:])))
# ValueError: substring not found

If you want to instead place such strings at the start, use 'LJP'.find(x[0]).

arranged_list = sorted(raw_list, key=lambda x: ('LJP'.find(x[0]), int(x[1:])))
# ['X11', 'L1', 'L2', 'L10', 'L12', 'J1', 'J10', 'P2', 'P5']

If you want to place them at the end, use -'PJL'.find(x[0]).

arranged_list = sorted(raw_list, key=lambda x: (-'PJL'.find(x[0]), int(x[1:])))
# ['L1', 'L2', 'L10', 'L12', 'J1', 'J10', 'P2', 'P5', 'X11']

CodePudding user response：

You can define a custom key function for sort as follows:

raw_list = ['L1', 'L2', 'J1', 'L10', 'L12', 'J10', 'P2', 'P5', 'P11']

def sort_key(s):
    alphabet_order={k: i for i, k in enumerate('LJP')}
    return (alphabet_order[s[0]], int(s[1:]))

output = sorted(raw_list, key=sort_key)
print(output)
# ['L1', 'L2', 'L10', 'L12', 'J1', 'J10', 'P2', 'P5', 'P11']

Or, using closure (twice faster):

def sort_key(alphabets):
    alphabet_order = {k: i for i, k in enumerate(alphabets)}
    return lambda s: (alphabet_order[s[0]], int(s[1:]))

output = sorted(raw_list, key=sort_key('LJP'))