title: Delimiter error from np.loadtxt Python
body: <p>I'm trying to sum some values in a list so i loaded the .dat file that contains the values, but the only way Python makes the sum of the data is by separate it with ','. Now, this is what I get.</p>
  
  <pre><code>    altura = np.loadtxt("bio.dat",delimiter=',',usecols=(5,),dtype='float')
    File "/usr/lib/python2.7/dist-packages/numpy/lib/npyio.py", line 846, in loadtxt
      vals = [vals[i] for i in usecols]
  IndexError: list index out of range
  </code></pre>
  
  <p>This is my code </p>
  
  <pre><code>import numpy as np
  
  altura = np.loadtxt("bio.dat",delimiter=',',usecols=(5,),dtype='str')
  print altura
  </code></pre>
  
  <p>And this is the file 'bio.dat'</p>
  
  <pre><code>1 Katherine Oquendo M 18    1.50    50  
  2 Pablo Restrepo    H 20    1.83    79  
  3 Ana Agudelo   M 18    1.58    45  
  4 Kevin Vargas  H 20    1.74    80  
  5 Pablo madrid  H 20    1.70    55  
  </code></pre>
  
  <p>What I intend to do is      </p>
  
  <pre><code>x=sum(altura)
  </code></pre>
  
  <p>What should i do with the 'separate'?</p>