python3: How can I add decimals that are inside a string

Question

I am a beginner and I want to add the decimals inside the string s

 totalsum=0
 s='1.23 2.4 3.123'
 for a in s:
    totalsum=totalsum+float(a)
 print (totalsum)

but when i try it says

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

How can I add those three decimals?

Answer 1

you're iterating on every character of the string. It works at first (well, for 1...), but when you reach . you get a parse error.

Now, you need to split your string. And be pythonic, do that in one line:

totalsum = sum(map(float,s.split()))

Answer 2

You can use regular expressions:

import re
s='1.23 2.4 -4.3 3.123 56'
data = sum(map(float, re.findall('(-*\d+\.*\d+)|\b-*\d+\b', s)))

Output:

58.453