I have a list that looks like this:
['9,7,4', '10,5,6,5,5', '10,8,5,3,0', '8,4,2']
How can i convert the numbers to ints and add the individual string values together?
So the desired out put would be
['20','31','26','14']
4 Answers
Use map to convert the splitted (using , as the delimiter) string values into int followed by a list comprehension to get the sum
input_list = ['9,7,4', '10,5,6,5,5', '10,8,5,3,0', '8,4,2']
output = [str(sum(map(int, x.split(',')))) for x in input_list]
print (output)
Output
['20', '31', '26', '14']
I edited after seeing your desired output as strings
[sum(map(int, group.split(','))) for group in l]
Comments
Someone mentioned eval, so I think you should take this a step further with a safe-eval alternative:
>>> import ast
>>> [ast.literal_eval(v.replace(',', '+')) for v in lst]
>>> [20, 31, 26, 14]
One thing I like about this answer is that it is purely a non-functional approach (no map inside a list comprehension, which is fine but I don't really believe in mixing paradigms).
Obviously this will only work if you have numbers separated by a single comma, without any leading or trailing characters and invalid arithmetic expressions.
I leave the conversion to string as an exercise.
Comments
If all strings are in this format you can try to use eval function - this will convert numbers into tuples from which you can count sum.
>>> l = ['9,7,4', '10,5,6,5,5', '10,8,5,3,0', '8,4,2']
>>> sums = [sum(numbers) for numbers in map(eval, l)]
>>> sums
[20, 31, 26, 14]
If you want output list to contain strings these values can be easily mapped:
[str(value) for value in sums]
# or
map(str, sums)
int(string)) and sum the resultant list.'9,7,4'? (If you can do that, you can do the rest.)splitthe string, convert each fragment to anint, applysum, convert back to astring.