Sorting a mixed list of ints and strings

Question

I am trying to sort the following mixed list of ints and strings, but getting a TypeError instead. My desired output order is sorted integers then sorted strings.

Answer 1

With function key

def func(i):
    return isinstance(i, str), i

stuff = ['Tractor', 184 ,'Lada', 11 ,'Ferrari', 5 , 'Chicken' , 68]
stuff.sort(key=func)

for x in stuff:
    print(x)

Change type str to int to get strings first.

Answer 2

I can see from your comment that you want integers to be sorted first then strings.

So we could sort two separate lists and join them as follows:

x=[4,6,9,'ashley','drooks','chay','poo','may']
intList=sorted([i for i in x if type(i) is int])
strList=sorted([i for i in x if type(i) is str])
print(intList+strList)

Output:

[4, 6, 9, 'ashley', 'chay', 'drooks', 'may', 'poo']

Answer 3

You can pass a custom key function to list.sort:

x = [4,6,9,'ashley','drooks','chay','poo','may']
x.sort(key=lambda v: (isinstance(v, str), v))

# result:
# [4, 6, 9, 'ashley', 'chay', 'drooks', 'may', 'poo']

---

This key function maps each element in the list to a tuple in which the first value is a boolean (True for strings and False for numbers) and the second value is the element itself, like this:

>>> [(isinstance(v, str), v) for v in x]
[(False, 4), (False, 6), (False, 9), (True, 'ashley'), (True, 'chay'),
 (True, 'drooks'), (True, 'may'), (True, 'poo')]

These tuples are then used to sort the list. Because False < True, this makes it so that integers are sorted before strings. Elements with the same boolean value are then sorted by the 2nd value in the tuple.