# Plotting Graph Functions using Gnuplot

arslanburney at gmail.com arslanburney at gmail.com
Thu Jun 12 17:01:17 CEST 2008

```Hello. Needed some help again. Im trying to calculate the best fit
line here. Given a set of points in a list. However, wirte in the end
where i plot the line it tells me tht the variable is not defined.
Either try correcting this or tell me a subsitute that i could use.
Thnks. Heres the code:

#File name Bestfit.py

import Gnuplot

def bestfit(uinput):

if not isinstance(uinput, list):
return False

else:

sigmax = sigmay = sigmaxy = sigmaxwhl = sigmaxsq = 0

for i in range(len(uinput)):

n = len(uinput)

sigmax = uinput[i][0] + sigmax
sigmay = uinput[i][1] + sigmay
sigmaxy = uinput[i][0] * uinput [i][1] + sigmaxy
sigmaxwhl = sigmax * sigmax
sigmaxsq = uinput[i][0] * uinput[i][0] + sigmaxsq
sigmaxsigmay = sigmax * sigmay

num = sigmaxsigmay - (n * sigmaxy)
den = sigmaxwhl - (n* sigmaxsq)

num2 = (sigmax * sigmaxy) - (sigmay * sigmaxsq)

intercept = num2 / den

c = intercept

y = m*x + c
plot (y)

-------

import Bestfit

Bestfit.bestfit([(2,3), (3,8), (5,7), (4,9)])

```