convert only number strings to integer in python list

Question

I have below python list

a= ['2','3','44','22','cat','2.2','-3.4','Mountain']

How can i get below output with one command (convert only numeric strings to numeric)

a = [2,3,44,22,'cat',2.2,-3.4,'Mountain']

i want to add to excel sheet with openpyxl so i can easily work with excel sheet. Otherwise i would need to change data manually in excel sheet later — user2774120, Jun 04 '20 at 04:33

yashtodi94 · Accepted Answer · 2020-06-04T05:49:17.240

3

Try converting to integer if numeric. For floats convert it blindly and if there is an exception, we can assume its a string.

foo = []
for i in a:
    if i.isnumeric():
        foo.append(int(i))
    else:
        try:
            foo.append(float(i))
        except ValueError:
            foo.append(i)

print(foo)

Output: [2, 3, 44, 22, 'cat', 2.2, -3.4, 'Mountain']

UPDATE A shorter version of the code would be:

foo = []
for i in a:
    try:
        foo.append(int(i) if float(i).is_integer() else float(i))
    except ValueError:
        foo.append(i)

print(foo)

edited Jun 04 '20 at 05:49

answered Jun 04 '20 at 05:37

yashtodi94

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Thanks.. what i needed – user2774120 Jun 04 '20 at 21:14

score 1 · Answer 2 · answered Jun 04 '20 at 05:40

1

The brute force way to do it is to go through the whole list and convert item by item. If the conversion fails, it will raise a ValueError exception which you can catch.

a= ['2','3','44','22','cat','2.2','-3.4','Mountain']

# enumerate is a handy function which gives you both the index and item for the 
# contents of an iterable.
for i, item in enumerate(a):

    try:
        a[i] = int(float(item))
    except ValueError:
        a[i] = item

print(a)

which gives

[2, 3, 44, 22, 'cat', 2, -3, 'Mountain']

answered Jun 04 '20 at 05:40

bfris

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This does not seem to convert `'2.2'` and `-3.4` correctly. – yashtodi94 Jun 04 '20 at 05:50
@yashtodi94, you're right. I thought to OP wanted integers. Your answer is better. – bfris Jun 04 '20 at 15:45

score 1 · Answer 3 · answered Jun 04 '20 at 06:04

1

Here is your code

b = [float(i) if i.lstrip('-').replace('.', '', 1).isdigit() else i for i in a  ]
print(b)

answered Jun 04 '20 at 06:04

Dev

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Thanks.. but its showing integers as float too – user2774120 Jun 04 '20 at 21:14

convert only number strings to integer in python list

3 Answers3