How to convert numerical strings inside a mixed list of list to int (Python)

Question

how do I convert all the numerical strings, inside a list of list that contains both alphabetical, and numerical strings, into an integer?

My Output:

[['69', ' Test', 'Results'], ['A', 'B', 'C'], ['D', '420', 'F']]

Intended Output:

[[69, ' Test', 'Results'], ['A', 'B', 'C'], ['D', 420, 'F']]

Note that my code reads a CSV file. Thanks everyone

def get_csv_as_table(a, b):
s = False
import csv

with open(a) as csv_file:
    file_reader = csv.reader(csv_file, delimiter=b)
    member = list(file_reader) 

    print(member)

print ("Enter filename: ")
a = input()
print ("Enter the delimiter: ")
b = input()
get_csv_as_table(a, b)

I tried using that yes, but im having trouble operating since its a list of lists :( — The Random Movieman
– The Random Movieman, Commented Nov 14, 2020 at 8:56
[[int(s) if s.isdigit() else s for s in lst] for lst in lists]. — jizhihaoSAMA
– jizhihaoSAMA, Commented Nov 14, 2020 at 8:57

Melvin Abraham · Accepted Answer · 2020-11-14 09:07:03Z

1

You can use list comprehension to achieve this. The only minor downside to this is that you will be creating a new list for this instead of modifying the existing list.

my_list = [['69', 'Test', 'Results'], ['A', 'B', 'C'], ['D', '420', 'F']]

filtered_list = [
    [int(item) if item.isdigit() else item for item in sub_list]
    for sub_list in my_list
]

If you want to edit the list in-place, you can use traditional for-loop. The following code will edit the existing list without creating a new list. This could turn out to be useful in case you have a large list.

my_list = [['69', 'Test', 'Results'], ['A', 'B', 'C'], ['D', '420', 'F']]

for i in range(len(my_list)):
    for j in range(len(my_list[i])):
        if my_list[i][j].isdigit():
            my_list[i][j] = int(my_list[i][j])

str.isdigit() checks if a given string is a number or not. An important note to keep in mind is that, it does not work for floating-point numbers, just integers. Once the condition passes, the item is converted to integer.

answered Nov 14, 2020 at 9:07

Melvin Abraham

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2 Comments

The Random Movieman Over a year ago

Yessss, very nice. Thanks alot my dude! that helped a lot

Melvin Abraham Over a year ago

If this answer seems helpful, you can accept and upvote it :)

azro · Accepted Answer · 2020-11-14 08:57:58Z

1

Yoy have to combine 2 levels of list-comprehension and use str.isdigit()

values = [
    [int(val) if val.isdigit() else val for val in row]
    for row in values
]

answered Nov 14, 2020 at 8:57

azro

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Comments

avarice · Accepted Answer · 2020-11-14 08:59:00Z

1

Try with 2-level list comprehension and int()+.isdigit() power combo in list comprehension ;-)

l=[['69', ' Test', 'Results'], ['A', 'B', 'C'], ['D', '420', 'F']]
l=[[int(y) if y.isdigit() else y for y in x] for x in l]
print(l)

Output:

[[69, ' Test', 'Results'], ['A', 'B', 'C'], ['D', 420, 'F']]

.isdigit() only works on string representation of pure integers, In case if you have floats too then replace '.' to nothing ;-)

l=[['69', ' Test', 'Results'], ['A', 'B', 'C'], ['D', '420', 'F']]
l=[[float(y) if y.replace('.','').isdigit() else y for y in x] for x in l]
print(l)

Output:

[[69.0, ' Test', 'Results'], ['A', 'B', 'C'], ['D', 420.0, 'F']]

answered Nov 14, 2020 at 8:59

avarice

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1 Comment

The Random Movieman Over a year ago

Thanks alot my dudes :) Youre a legend

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