title: python pandas read_csv thousands separator does not work
body: <p>I use pandas read_csv to read a simple csv file. However, it has <code>ValueError: could not convert string to float:</code> which I do not understand why.</p>
  
  <p>The code is simply</p>
  
  <pre><code>rawdata = pd.read_csv( r'Journal_input.csv' ,
                        dtype = { 'Base Amount' : 'float64' } , 
                        thousands = ',' ,
                        decimal = '.',
                        encoding = 'ISO-8859-1')
  </code></pre>
  
  <p>But I get this error</p>
  
  <blockquote>
    <p>pandas\parser.pyx in pandas.parser.TextReader.read
    (pandas\parser.c:10415)()</p>
    
    <p>pandas\parser.pyx in pandas.parser.TextReader._read_low_memory
    (pandas\parser.c:10691)()</p>
    
    <p>pandas\parser.pyx in pandas.parser.TextReader._read_rows
    (pandas\parser.c:11728)()</p>
    
    <p>pandas\parser.pyx in pandas.parser.TextReader._convert_column_data
    (pandas\parser.c:13162)()</p>
    
    <p>pandas\parser.pyx in pandas.parser.TextReader._convert_tokens
    (pandas\parser.c:14487)()</p>
    
    <p>ValueError: could not convert string to float: '79,026,695.50'</p>
  </blockquote>
  
  <p>How can it possible to get error when converting a string of '79,026,695.50' to float? I have already specified the two options                       </p>
  
  <pre><code>thousands = ',' ,
  decimal = '.',
  </code></pre>
  
  <p>Is it some problem our my code or a bug in pandas?</p>