I want to iterate through a list that contains a mix of lists and non-list elements. Here's an example:
a = [[1, 2, 3, 4, 5], 8, 9, 0, [1, 2, 3, 4, 5]]
I know how to iterate through a mandatory list of lists, but in this case I don't know how to do it. My objective is to compare one value of the nested list with another value in the list. For example in this case: [1, 2, 3, 4, 5] and 8
Is this what you want:
thelist = [[1, 2, 3, 4, 5], 5, 6, 7, 8, 10, [9, 0, 1, 8]]
# Remove the 5 from the first inner list because it was found outside.
# Remove the 8 from the other inner list, because it was found outside.
expected_output =[[1, 2, 3, 4], 5, 6, 7, 8, 10, [9, 0, 1]]
Here's a way to do it:
thelist = [[1, 2, 3, 4, 5], 5, 6, 7, 8, [9, 0, 1, 8]]
expected_output =[[1, 2, 3, 4], 5, 6, 7, 8, [9, 0, 1]]
removal_items = []
for item in thelist:
if not isinstance(item, list):
removal_items.append(item)
for item in thelist:
if isinstance(item, list):
for remove in removal_items:
if remove in item:
item.remove(remove)
print thelist
assert thelist == expected_output
filter(lambda elem: type(elem) is not list, a), which is a built-in function that will remove any list element from your main list. As for create again the list, you don't have to. The code from @jgritty modifies your original list directly.A slightly different version than the answer from jgritty. The differences:
int elements from your listlista, so that we can safely remove elements from a itself at the same timeuse list comprehension to remove members of nested lists that are already in the main list
a = [[1, 2, 3, 4, 5], 5, 6, 7, 8, [9, 0, 1, 8]]
print a
numbers = set(filter(lambda elem: type(elem) is not list, a))
for elem in a:
if type(elem) is list:
elem[:] = [number for number in elem if number not in numbers]
print a
for elem in a[:]: instead of for elem in a:?a[:] is an idiomatic way of getting a copy of a list in Python. It is not a good idea to modify a list while iterating over it, as explained in the online docelem list that needs to be copied I think. It doesn't seem that you're modifying a, only its elements. Also, I don't iterate over the inner lists for exactly that reason.a = [[1, 2, 3, 4, 5], 8, 9, 0, [1, 2, 3, 4, 5]]
for x in a:
if type(x) is list:
for y in x:
print y
else:
print x
or use
isinstance(x, list)
You can check if the object of the iteration is a ListType (http://docs.python.org/library/types.html) and iterate it further.
I cant remember now the exact command but there is something like type(x) that you can use to get the object's type.
