Convert a List of string to Int or Float as available

Question

I have list as:

list = ['67.50', '70.00', '72.50', '75.00', '77.50', '80.00', '82.50']

I want to check if the string is a foat then it should be converted to float and if the string is a int then it should be converted to int.

Desired Output:

list = [67.50, 70, 72.50, 75, 77.50, 80, 82.5]

There is a nice list (perhaps outdated, but instructive) about what may and may not parse as a float. But in your case, it may be sufficient to see if there is a decimal point in the number and if not, parse as int else float: `[float(n) if '.' in n else int(n) for n in list]` — smichr, Jun 15 '19 at 12:35
that one is close too: https://stackoverflow.com/questions/33130279/convert-a-list-of-strings-to-either-int-or-float — Jean-François Fabre, Jun 15 '19 at 13:15

score 5 · Accepted Answer · answered Jun 15 '19 at 12:35

5

You could make use of float.is_integer():

>>> lst = ['67.50', '70.00', '72.50', '75.00', '77.50', '80.00', '82.50']
>>> [int(x) if x.is_integer() else x for x in map(float, lst)]
[67.5, 70, 72.5, 75, 77.5, 80, 82.5]

answered Jun 15 '19 at 12:35

Chris_Rands

38,994
14
83
119

1

That map(float, lst) is smart. I also agree with using lst, instead of list as the variable name as list is also a built-in function of Python. – Deepstop Jun 15 '19 at 12:40

yatu · Answer 2 · 2019-06-15T13:05:41.080

2

Here's one way using a list comprehension, and checking if the modulo operator of a given string converted to float is 0.0, to either convert it to float or to integer.

Also note that it is not possible to directly use the built-in int function to construct an integer from a string with decimals, to overcome this I'm using f-strings, where g will print a given number as a fixed-point number, with in this case 0 decimal places:

l = ['67.50', '70.00', '72.50', '75.00', '77.50', '80.00', '82.50']

[int(f'{float(i):g}') if float(i)%1 == 0. else float(i) for i in l]
# [67.5, 70, 72.5, 75, 77.5, 80, 82.5]

For python versions under 3.6 use .format for string formatting:

[int('{0:g}'.format(float(i))) if float(i)%1 == 0. else float(i) for i in l]
# # [67.5, 70, 72.5, 75, 77.5, 80, 82.5]

edited Jun 15 '19 at 13:05

answered Jun 15 '19 at 12:29

yatu

86,083
12
84
139

1

What about `70` ? – Devesh Kumar Singh Jun 15 '19 at 12:35
What about it @devesh? – yatu Jun 15 '19 at 12:36
I mean the code will throw an exception if `'70'` is an element in the list – Devesh Kumar Singh Jun 15 '19 at 12:36
Well that is assuming there are integers, but apparently all numbers are decimals – yatu Jun 15 '19 at 12:37
Updated @DeveshKumarSingh should work now with ints too – yatu Jun 15 '19 at 12:49

score 1 · Answer 3 · answered Jun 15 '19 at 12:37

Well this works, but there's probably a better way. It handles the case like 75.00 which you want to convert to integer and not a float.

from math import floor
list = ['67.50', '70.00', '72.50', '75.00', '77.50', '80.00', '82.50']
print([int(floor(float(l))) if float(l)-floor(float(l)) == 0 else float(l) for l in list])

Output is

python test.py
[67.5, 70, 72.5, 75, 77.5, 80, 82.5]

score 1 · Answer 4 · answered Jun 15 '19 at 12:54

Here is another version:

list = ['67.50', '70.00', '72.50', '75.00', '77.50', '80.00', '82.50']

new_list = []

for x in list:
    float_x = float(x)
    int_x = int(float_x)
    if int_x == float_x:
        new_list.append(int_x)
    else:
        new_list.append(float_x)

for y in new_list:
    print(type(y))

Returns:

<class 'float'>
<class 'int'>
<class 'float'>
<class 'int'>
<class 'float'>
<class 'int'>
<class 'float'>

Convert a List of string to Int or Float as available

4 Answers4