title: converting a list of strings(csv) to a list of floats
body: <p>I am having some difficulty converting this list of strings into a list of floats. I tried this two ways and each returned different errors.</p>
  
  <pre><code>import csv
  import math
  
  unemp_reader = csv.reader(open('unemp.csv', 'rU'))
  unemp_lines = list(unemp_reader)
  
  for rows in unemp_lines:     #tried this way, but error tells me indices must be integers 
      i = 1
      for i in rows:
          a = map(float, unemp_lines[i])
          float_list.append(a)
      print float_list
  
  for row in unemp_lines:  #tried this way but the list returned is empty
      y = row[1].split(",")[1:-1]
      float_list = [float(i) for i in y if i]
  print float_list
  </code></pre>