title: Cannot convert array to floats python
body: <p>I'm having a problem that seems like the answer would be easily explained. 
  I'm struggling to convert my array elements to floats (so that I can multiply, add on them etc)</p>
  
  <pre><code>import csv
  import os
  import glob
  import numpy as np
  
  def get_data(filename):
      with open(filename, 'r') as f:
          reader = csv.reader(f)                      
          return list(reader)
  
  all_data = []
  
  path=raw_input('What is the directory?')       
  for infile in glob.glob(os.path.join(path, '*.csv')):
       all_data.extend(get_data(infile))
  a = np.array(all_data)
  current_track_data=a[0:,[8,9,10,11,12]]
  abs_track_data=a[0:,7]
  </code></pre>
  
  <p>and I get the error:</p>
  
  <pre><code>&gt; --------------------------------------------------------------------------- ValueError                                Traceback (most recent call last) C:\Users\AClayton\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.0.3.1262.win-x86_64\lib\site-packages\IPython\utils\py3compat.pyc in execfile(fname, glob, loc)
      174             else:
      175                 filename = fname
  --&gt; 176             exec compile(scripttext, filename, 'exec') in glob, loc
      177     else:
      178         def execfile(fname, *where):
  &gt; 
  &gt; C:\Users\AClayton\Current\python begin\code_tester2.py in &lt;module&gt;()
  &gt;      18 for infile in glob.glob(os.path.join(path, '*.csv')): # performs loop for each file in the specified path with extension .csv
  &gt;      19      all_data.extend(get_data(infile))
  &gt; ---&gt; 20      a = np.ndarray(all_data, dtype=float)
  &gt;      21 
  &gt;      22      current_track_data=a[0:,[8,9,10,11,12]]
  &gt; 
  &gt; ValueError: sequence too large; must be smaller than 32
  </code></pre>