title: pandas: float_format and decimal sign not working properly
body: <p>I am trying to write a pandas DataFrame <code>df</code> to a csv-file using pandas' <a href="http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.to_csv.html" rel="nofollow"><code>to_csv</code></a> method with the following line:</p>
  
  <pre><code>df.to_csv(f, index=False, header=False, decimal=',', sep=' ', float_format='%.3f')
  </code></pre>
  
  <p>Which gives a csv-file like the following:</p>
  
  <pre><code>295.998 292.500 293.000 293.000
  295.998 292.500 293.000 293.000
  295.998 292.500 293.000 293.000
  </code></pre>
  
  <p>So the <code>float_format</code> option works pretty well, as all numbers have three decimal digits. However, the <code>decimal</code> option (<code>decimal = ','</code>) does not seem to work, since the decimal sign is a dot and not a comma.</p>
  
  <p>What I am interested is something like the following:</p>
  
  <pre><code>295,998 292,500 293,000 293,000
  295,998 292,500 293,000 293,000
  295,998 292,500 293,000 293,000
  </code></pre>
  
  <p>How can I convience pandas to use three decimal digits and the desired comma as decimal sign?</p>