Converting a string numbers list into a float numbers list

I`ve been trying to convert a string numbers list into float and get the max of this list but I keep getting this error:

ValueError: could not convert string to float: '.'

My attempt was to get a list like ls = ['1','2','3','0.5'] and convert using this function

def convert_to_int(ls: list):
    values = [float(a) for a in ls]
    return (len(values), values)

print(max(ls, key=convert_to_int))

Why I’m having this error? Can someone help me?

>Solution :

I think, what you’re looking for is:

max(ls, key=float)

output: '3'

This will get the max value of your string list, using a temporary float conversion within max