Python Could Not Convert String To Float

How to resolve the error “could not convert string to float: id”?

here is my code which is showing the same error called  “could not convert string to float: id”

import os,sys 

from scipy import stats 

import numpy as np 

f=open('data2.txt', 'r').readlines()

 N=len(f)-1 

for j in range(0,N): 

w=f[j].split() 

l1=w[1:8] 

l2=w[8:15] 

li1=[float(y) for y in l1] 

li2=[float(y) for y in l2] 

result=stats.ttest_ind(li1,li2) 

print result[1]