ValueError: too many values to unpack, while trying to unpack a simple.txt file
<p>I have this simple code to read and plot a .txt file </p>

<pre><code>import sys
import os
import numpy
import matplotlib.pyplot as plt
from pylab import *

exp_sum = 'exponential_sum.txt'

Term, Absolute_error, Relative_error= numpy.loadtxt(exp_sum, unpack =True)

plt.semilogy(Term,Absolute_error, 'm^-')
plt.semilogy(Term,Relative_error, 'g-')


xlabel('Number of terms N')
ylabel('Absolute and Relative approximation error')
legend(['Absolute error', 'relative error'], loc = 'upper right')
title('Testing convergence of exponential series with respect to error vs iteration terms')
show()
</code></pre>

<p>which worked fine so far, now it just gives me this weird error while trying to plot this simple text file. please help me how to resolve this value error, the .txt file is also attached.</p>

<pre><code>#Term   Exponential_sum    Absolute_error       Relative_error       
0       1.0                1.71828182846        0.632120558829       
1       2.0                0.718281828459       0.264241117657       
2       2.5                0.218281828459       0.0803013970714      
3       2.66666666667      0.0516151617924      0.0189881568762      
4       2.70833333333      0.00994849512571     0.00365984682734     
5       2.71666666667      0.00161516179238     0.000594184817582    
6       2.71805555556      0.00022627290349     8.3241149288e-05     
7       2.71825396825      2.78602050767e-05    1.02491966745e-05    
8       2.71827876984      3.05861777505e-06    1.12520259784e-06    
9       2.71828152557      3.02885852843e-07    1.11425478283e-07    
10      2.71828180115      2.73126605776e-08    1.00477663102e-08    
11      2.7182818262       2.26055218988e-09    8.31610676352e-10    
12      2.71828182829      1.72876379878e-10    6.35976660213e-11    
13      2.71828182845      1.22857279905e-11    4.51966674753e-12    
14      2.71828182846      8.14903700075e-13    2.99786317792e-13    
15      2.71828182846      5.01820807131e-14    1.84609558095e-14    
16      2.71828182846      2.22044604925e-15    8.1685645175e-16     
17      2.71828182846      4.4408920985e-16     1.6337129035e-16     
18      2.71828182846      4.4408920985e-16     1.6337129035e-16     
19      2.71828182846      4.4408920985e-16     1.6337129035e-16
</code></pre>

<p>You're trying to unpack four columns into three variables -- the <code>Exponential_sum</code> variable is missing!</p>

python numpy