How to lowercase of individual word in two dimensional list?

Question

I have two-dimensional list:

list=[["Hello", "mY", "WORLD"], ["MY", "yOur", "ouRS"]]

My desired output is:

new_list=[["hello", "my", "world"], ["my", "your", "ours"]]

Answer 1

You can do it with a list comprehension which contains, as its elements, another list comprehension. At the root of it all is a call to str.lower() to create new lower-casified strings.

Aside: it is better not to name your variables after built-in types. Try my_list=, lst=, or some descriptive name like mixed_case_words=, instead of list=

new_list = [ [ item.lower() for item in sublist ] for sublist in old_list]

If you prefer loops, you can do it with nested for loops:

new_list = []
for sublist in old_list:
    new_sublist = []
    for item in sublist:
        new_sublist.append(item.lower())
    new_list.append(new_sublist)

Answer 2

You may try this:

list=[["Hello", "mY", "WORLD"], ["MY", "yOur", "ouRS"]]
new_list = [ [ i.lower() for i in innerlist ] for innerlist in list]
print(new_list)

Output:

[['hello', 'my', 'world'], ['my', 'your', 'ours']]

Answer 3

Nested list comprehension will do for your case

lst = [["Hello", "mY", "WORLD"], ["MY", "yOur", "ouRS"]]
new_lst = [ [i.lower() for i in j] for j in lst]
# [["hello", "my", "world"], ["my", "your", "ours"]

We can do something like below also using eval and str method, this shall handle any depth of nested list of string

lst = [["Hello", "mY", "WORLD"], ["MY", "yOur", "ouRS"]]
# replace eval with ast.literal_eval for safer eval
new_lst = eval(str(lst).lower())
# [["hello", "my", "world"], ["my", "your", "ours"]