Python Forum

In this programme i'm trying to solve a mathematical ratio problem, then calculate the squareroot, however, whenever i try to give it input like this: 2.5, it throws out the following error:

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

, obviously it doesn't recognise the "." as a number. Here's the complete code:

# !/usr/bin/python
# -*- coding: utf8 -*-

import math


def data_processing():
    
    ratio = list(raw_input('ratio numbers: ').replace(' ', ''))

    r1 = float(ratio[0]) * float(ratio[1])
    r2 = float(ratio[2]) * float(ratio[3])

    a = r1/r2

    print math.sqrt(a)


data_processing()

How can i get the float() function to recognise a number like this: 2.5 as a floating point number with a decimal point instead of a group of numbers with the string "."? what is the easiest way to fix this? thanks

Python does recognize '.' as float.
You need to print ratio. To see your error.

what is expect user input at this line

ratio = list(raw_input('ratio numbers: ').replace(' ', ''))

>>> var1 = '2.5'
>>> var2 = float(var1)
>>> var2
2.5
>>> type(var2)
<type 'float'>
>>>

perhaps you want to write this sample code like that :

ratio = list(raw_input('ratio numbers: ').replace(' ', '.'))