Question

I want to sort string array using python.

I have a string array

str_array = {string1, string2, string3}
all string formats are AB-CD-EFGH-IJ-NAME ------> 12-34-5678-09-PHOTO

AB= 00 to 99
CD= 00 to 99
EFGH= 0000 to 9999
IJ= 00 to 99
NAME= any alphabetic name

I want sort string first with there equivalent numeric value (remove “-” from numeric part of string) then alphabetic order.

For example 12-34-5678-09-PHOTO will be 1234568809-PHOTO.

Answer 1

Define a key function which takes an element of the iterable str_array as input, and returns a tuple key consisting of the integer (first) and name (second):

def mykey(text):
    numtxt, name = text.rsplit('-',1)
    numtxt = int(numtxt.replace('-',''))
    return (numtxt, name)

new_str = sorted(str_array, key = mykey)

For example,

In [30]: sorted(['12-34-5678-09-PHOTO', '12-34-5678-09-MOTOR', '12-04-5678-09-PHOTO', ], key = mykey)
Out[30]: ['12-04-5678-09-PHOTO', '12-34-5678-09-MOTOR', '12-34-5678-09-PHOTO']

For more on this sorting technique, see the HOWTO Sort wiki.

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Note that sorted returns a new list. If you wish to sort str_array in-place, then use

str_array.sort(key = mykey)