ahya.py

#encoding:utf-8
from __future__ import division
import pylab


l = pylab.loadtxt("data")
l = l.T

l_ =  pylab.np.polyfit(l[1],l[0],1)

def p(x, l_):
    sum = 0
    for i in range(len(l_)):
        sum += l_[i]*x**(len(l_)-i-1)
    return sum

def p_name(l_):
    l = []
    for i in range(len(l_)):
        l.append("{0:1.3e}x^{1}".format(l_[i],len(l_)-i-1))
    return "+".join(l)

pylab.title("Angle dependence of lattice constant")
pylab.xlabel(u"cos^2/sin")
pylab.ylabel("a[nm]")

pylab.plot(l[1],l[0],"x",label="test results")
pylab.plot(l[1],p(l[1],l_),"-",label = p_name(l_))
pylab.legend()
pylab.show()