How to sort alphanumeric list in python

Question

I have a list as

a = [["1", "ok", "na"], ["15", "asd", "asdasd"], ["100", "uhu", "plo"], ["10", "iju", "tlo"], ["ISC_1", "des", "det"], ["12", "asd", "assrg"], ["ARF", "asd", "rf"]]

I want this list to be sorted as below:

[['1', 'ok', 'na'], ['10', 'iju', 'tlo'], ['12', 'asd', 'assrg'], ['15', 'asd', 'asdasd'], ['100', 'uhu', 'plo'], ['ARF', 'asd', 'rf'], ['ISC_1', 'des', 'det']]

I have used a.sort()

It is resulting as below:

[['1', 'ok', 'na'], ['10', 'iju', 'tlo'], ['100', 'uhu', 'plo'], ['12', 'asd', 'assrg'], ['15', 'asd', 'asdasd'], ['ARF', 'asd', 'rf'], ['ISC_1', 'des', 'det']]

Please help me how to sort in this case.

stackoverflow.com/questions/20099669/… possibly answer your question — augustoccesar
– augustoccesar, Commented Oct 27, 2017 at 13:06
Possible duplicate of Python Sort Multidimensional Array Based on 2nd Element of Subarray — augustoccesar
– augustoccesar, Commented Oct 27, 2017 at 13:06

Neo · Accepted Answer · 2017-10-27 13:35:02Z

6

You can use the key named argument.
It accepts a function that returns the value the sorting function should compare items by.

sorted(a, key = lambda l: int(l[0]))

edited Oct 27, 2017 at 13:35

answered Oct 27, 2017 at 13:06

Neo

3,8162 gold badges24 silver badges33 bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

Sandeep Lade Over a year ago

Will it work in python2.7 ? getting below error

>>> sort(a, key = lambda l: int(l[0]))  Traceback (most recent call last):   File "<pyshell#43>", line 1, in <module>     sort(a, key = lambda l: int(l[0])) NameError: name 'sort' is not defined

Leonhard Triendl Over a year ago

with ´a.sort(key = lambda l: int(l[0]))´ or ´b=sorted(a,key = lambda l: int(l[0]))´

Shanky Over a year ago

what if the case my list is a = [["1", "ok", "na"], ["15", "asd", "asdasd"], ["100", "uhu", "plo"], ["10", "iju", "tlo"], ["ISC_1", "des", "det"]]

Shanky Over a year ago

It is throwing invalid literal for int() with base 10: 'ISC_1'

Leonhard Triendl Over a year ago

what do you want do happen with ISC? should it come last or first? if it should come last: a.sort(key = lambda l: int(l[0]) if l[0].isnumeric() else 99999)

|

Leonhard Triendl · Accepted Answer · 2017-10-27 13:31:02Z

3

To be ready for non numeric values you can use

a.sort(key = lambda l: int(l[0]) if l[0].isnumeric() else 99999)
# or
b=sorted(a,key = lambda l: int(l[0]) if l[0].isnumeric() else 99999)

to see non-numeric last or

a.sort(key = lambda l: int(l[0]) if l[0].isnumeric() else 0)
# or
b=sorted(a,key = lambda l: int(l[0]) if l[0].isnumeric() else 0)

to see them first

answered Oct 27, 2017 at 13:31

Leonhard Triendl

8227 silver badges16 bronze badges

1 Comment

Shanky Over a year ago

Thanks for the response. I want the result as [['1', 'ok', 'na'], ['10', 'iju', 'tlo'], ['12', 'asd', 'assrg'], ['15', 'asd', 'asdasd'], ['100', 'uhu', 'plo'], ['ARF', 'asd', 'rf'], ['ISC_1', 'des', 'det']] With ARF first and ISC_1 last

ragardner · Accepted Answer · 2017-12-12 08:46:39Z

You can use a natural sorting key, very easy to setup with the regular expression re.split()

import re
try:
    # fast string checking and conversion
    from fastnumbers import *
except:
    pass

def natural_sort_key_for_list_of_lists(sublist):
    return [int(element) if element.isdigit() else element
            for element in re.split("([0-9]+)",sublist[0])]
    # put whichever index of the sublist you want here ^

a = [["1", "ok", "na"],
     ["15", "asd", "asdasd"],
     ["100", "uhu", "plo"],
     ["10", "iju", "tlo"],
     ["ISC_1", "des", "det"],
     ["12", "asd", "assrg"],
     ["ARF", "asd", "rf"]]

a.sort(key=natural_sort_key_for_list_of_lists)

for l in a:
    print (l)

result:

['1', 'ok', 'na']
['10', 'iju', 'tlo']
['12', 'asd', 'assrg']
['15', 'asd', 'asdasd']
['100', 'uhu', 'plo']
['ARF', 'asd', 'rf']
['ISC_1', 'des', 'det']

Collectives™ on Stack Overflow

How to sort alphanumeric list in python

3 Answers 3

8 Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

8 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related