如何使用列表理解删除列表中列表中的项目

Question

I have a large list like this:

mylist = [['pears','apples','40'],['grapes','trees','90','bears']]

I'm trying to remove all numbers within the lists of this list. So I made a list of numbers as strings from 1 to 100:

def integers(a, b):
         return list(range(a, b+1))

numb = integers(1,100)

numbs = []
for i in range(len(numb)):
    numbs.append(str(numb[i])) # strings

numbs = ['1','2',....'100']

How can I iterate through lists in mylist and remove the numbers in numbs ? Can I use list comprehension in this case?

Answer 1

如果数字始终在子列表的最后

mylist = [ x[:-1] for x in mylist ]

Answer 2

mylist = [[item for item in sublist if item not in numbs] for sublist in mylist] should do the trick.

However, this isn't quite what you've asked. Nothing was actually removed from mylist , we've just built an entirely new list and reassigned it to mylist . Same logical result, though.

Answer 3

If numbers are always at the end and only once, you can remove the last item like:

my_new_list = [x[:-1] for x in mylist]

If there is more (of if they are not ordered), you have to loop thru each elements, in that case you can use:

my_new_list = [[elem for elem in x if elem not in integer_list] for x in mylist]

I would also recommend to generate the list of interger as follow :

integer_list = list(map(str, range(1, 100)))

I hope it helps :)

Answer 4

Instead of enumerating all the integers you want to filter out you can use the isdigit to test each string to see if it really is only numbers:

mylist = [['pears','apples','40'],['grapes','trees','90','bears']]
mylist2 = [[x for x in aList if not x.isdigit()] for aList in mylist]
print mylist2
[['pears', 'apples'], ['grapes', 'trees', 'bears']]

Answer 5

If you have the following list:

mylist = [['pears','apples','40'],['grapes','trees','90','bears']]
numbs = [str(i) for i in range(1, 100)]

Using list comprehension to remove element in numbs

[[l for l in ls if l not in numbs] for ls in mylist]

This is a more general way to remove digit elements in a list

[[l for l in ls if not l.isdigit()] for ls in mylist]