How can I use a nested list comprehension in Python to process a nested list?

General Discussions
1

How can I use a nested list comprehension in Python to process a nested list?

I have the following nested list:

l = [[‘40’, ‘20’, ‘10’, ‘30’], [‘20’, ‘20’, ‘20’, ‘20’, ‘20’, ‘30’, ‘20’], [‘30’, ‘20’, ‘30’, ‘50’, ‘10’, ‘30’, ‘20’, ‘20’, ‘20’], [‘100’, ‘100’], [‘100’, ‘100’, ‘100’, ‘100’, ‘100’], [‘100’, ‘100’, ‘100’, ‘100’]]

I want to convert each element in this list to a float. Here is the code I currently have:


newList = []
for x in l:
    for y in x:
        newList.append(float(y))

How can I solve this problem using a nested list comprehension in Python?

2

Nested List Comprehension for Flattening and Conversion:

l = [['40', '20', '10', '30'], ['20', '20', '20', '20', '20', '30', '20'], ['30', '20', '30', '50', '10', '30', '20', '20', '20'], ['100', '100'], ['100', '100', '100', '100', '100'], ['100', '100', '100', '100']]
newList = [float(y) for x in l for y in x]

This approach directly flattens the list and converts each element to a float.

3

List Comprehension with Nested Loops for Each Inner List:

l = [['40', '20', '10', '30'], ['20', '20', '20', '20', '20', '30', '20'], ['30', '20', '30', '50', '10', '30', '20', '20', '20'], ['100', '100'], ['100', '100', '100', '100', '100'], ['100', '100', '100', '100']]
newList = [[float(y) for y in x] for x in l]

This solution preserves the nested structure of the original list while converting each element within the inner lists to float.

4

Using a Nested List Comprehension with Mapping:

l = [['40', '20', '10', '30'], ['20', '20', '20', '20', '20', '30', '20'], ['30', '20', '30', '50', '10', '30', '20', '20', '20'], ['100', '100'], ['100', '100', '100', '100', '100'], ['100', '100', '100', '100']]
newList = list(map(lambda x: [float(i) for i in x], l))

This uses a map in combination with list comprehension to convert each inner list’s elements to float without changing the overall structure.