Python Math - TypeError: 'NoneType' object is not subscriptable
lista = list.sort(lista)
This should be
lista.sort()
The .sort()
method is in-place, and returns None. If you want something not in-place, which returns a value, you could use
sorted_list = sorted(lista)
Aside #1: please don't call your lists list
. That clobbers the builtin list type.
Aside #2: I'm not sure what this line is meant to do:
print str("value 1a")+str(" + ")+str("value 2")+str(" = ")+str("value 3a ")+str("value 4")+str("\n")
is it simply
print "value 1a + value 2 = value 3a value 4"
? In other words, I don't know why you're calling str on things which are already str.
Aside #3: sometimes you use print("something")
(Python 3 syntax) and sometimes you use print "something"
(Python 2). The latter would give you a SyntaxError in py3, so you must be running 2.*, in which case you probably don't want to get in the habit or you'll wind up printing tuples, with extra parentheses. I admit that it'll work well enough here, because if there's only one element in the parentheses it's not interpreted as a tuple, but it looks strange to the pythonic eye..
The exception TypeError: 'NoneType' object is not subscriptable
happens because the value of lista
is actually None
. You can reproduce TypeError
that you get in your code if you try this at the Python command line:
None[0]
The reason that lista
gets set to None is because the return value of list.sort()
is None
... it does not return a sorted copy of the original list. Instead, as the documentation points out, the list gets sorted in-place instead of a copy being made (this is for efficiency reasons).
If you do not want to alter the original version you can use
other_list = sorted(lista)