How to let python use negative numbers
Question: I've been making a linear equation calculator and I'm wondering how to let
python use negative numbers. Like int(), float() etc...

here is my code.

    
    
    import time
    
    print("Hello and welcome to the linear equation calculator.")
    
    time.sleep(2)
    
    print("Enter the first co-ordinate like this - (xx, yy): ")
    coordnte1 = input()
    
    print("Now enter the second co-ordinate like this, with the brackets, - (xx,yy): ")
    coordnte2 = input()
    
    print("Now the y-intercept: ")
    yintrcpt = input()
    
    ydif = coordnte2[1] - coordnte1[1]
    xdif = coordnte2[0] - coodrnte1[0]
    g = ydif / xdif
    
    print("y = " + g + "x + " + yintrcpt)
    

And the problem:

    
    
    Traceback (most recent call last):
      File "C:/Users/Dale/Documents/GitHub/new_python_rpi_experiments/linear.py", line 17,   in <module>
        ydif = coordnte2[1] - coordnte1[1]
    TypeError: unsupported operand type(s) for -: 'str' and 'str'
    

I'm very new to Python, so any help would be appreciated.


Answer: What your are reading from the input is a _string_ , you need to extract the
coordinates and convert them to _float_ , for example:

    
    
    print("Enter the first co-ordinate like this - (xx, yy): ")
    s = input()
    

Now `s = "(34, 23)"` is a _string_ and you need to process it (eliminate
parens, comma, etc...):

    
    
    coords = [float(coord) for coord in s.strip('()').split(',')]
    

Now coords is a list(array) of floats and you can do `coords[0]- coords[1]`
and so on.

