ValueError: could not convert string to float: id

Question

I'm running the following python script:

#!/usr/bin/python 

import os,sys 

from scipy import stats 

import numpy as np 

f=open('data2.txt', 'r').readlines() 

N=len(f)-1 

for i in range(0,N): 

w=f[i].split() 

l1=w[1:8] 

l2=w[8:15] 

list1=[float(x) for x in l1] 

list2=[float(x) for x in l2]

result=stats.ttest_ind(list1,list2) 

print result[1]

However, I got errors like:

ValueError: could not convert string to float: id

I'm confused by this. When I try this for only one line in interactive section, instead of for loop using the script:

>>> from scipy import stats 

>>> import numpy as np 

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

>>> w=f[1].split() 

>>> l1=w[1:8] 

>>> l2=w[8:15] 

>>> list1=[float(x) for x in l1] 

>>> list1 

[5.3209183842, 4.6422726719, 4.3788135547, 5.9299061614, 5.9331108706, 5.0287087832, 4.57...]

It works well.

Can anyone explain a little bit about this? Thank you.

Answer 1

To get rid of this error you try it in the interactive prompt you are trying only first line, so the best way is to print the line where you are getting this error and you will know the wrong line e.g.

#!/usr/bin/python 

import os,sys 

from scipy import stats 

import numpy as np 

f=open('data2.txt', 'r').readlines() 

N=len(f)-1 

for i in range(0,N): 

w=f[i].split() 

l1=w[1:8] 

l2=w[8:15] 

try: 

list1=[float(x) for x in l1] 

list2=[float(x) for x in l2] 

except ValueError,e: 

print("error",e,"on line",i) result=stats.ttest_ind(list1,list2) 

print(result[1])

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