How to sort python list of strings of numbers
Question:
I am trying to sort list of strings containing numbers
a = ["1099.0","9049.0"]
a.sort()
a
['1099.0', '9049.0']
b = ["949.0","1099.0"]
b.sort()
b
['1099.0', '949.0']
a
['1099.0', '9049.0']
But list b is sorting and not list a
Answers:
Convert them to int or float or even decimal (since it has trailing numbers)
>>> b = [float(x) for x in b]
>>> b.sort()
>>> b
[949.0, 1099.0]
You want to sort based on the float values (not string values), so try:
>>> b = ["949.0","1099.0"]
>>> b.sort(key=float)
>>> b
['949.0', '1099.0']
use a lambda inside sort to convert them to float and then sort properly:
a = sorted(a, key=lambda x: float(x))
so you will mantain them as strings but sorted by value and not lexicographically
In case anybody is dealing with numbers and extensions such as 0.png, 1.png, 10.png, 2.png…
We need to retrieve and sort the characters before the extension since this extension does not let us to convert the names to floats:
myList = sorted(myList, key=lambda x: int(x[:-4]))
PD: After many years I have edited this answer changing float to int because I guess it is more efficient and more precise. It is a rare case to need floats for this purpose and it might bring errors.
I am trying to sort list of strings containing numbers
a = ["1099.0","9049.0"]
a.sort()
a
['1099.0', '9049.0']
b = ["949.0","1099.0"]
b.sort()
b
['1099.0', '949.0']
a
['1099.0', '9049.0']
But list b is sorting and not list a
Convert them to int or float or even decimal (since it has trailing numbers)
>>> b = [float(x) for x in b]
>>> b.sort()
>>> b
[949.0, 1099.0]
You want to sort based on the float values (not string values), so try:
>>> b = ["949.0","1099.0"]
>>> b.sort(key=float)
>>> b
['949.0', '1099.0']
use a lambda inside sort to convert them to float and then sort properly:
a = sorted(a, key=lambda x: float(x))
so you will mantain them as strings but sorted by value and not lexicographically
In case anybody is dealing with numbers and extensions such as 0.png, 1.png, 10.png, 2.png…
We need to retrieve and sort the characters before the extension since this extension does not let us to convert the names to floats:
myList = sorted(myList, key=lambda x: int(x[:-4]))
PD: After many years I have edited this answer changing float to int because I guess it is more efficient and more precise. It is a rare case to need floats for this purpose and it might bring errors.