title: Read excel data into pandas dataframe to 20 decimal places
body: <p>I am trying to read data from excel using pandas.ExcelFile() into a dataframe, and then outputting a text file using to_csv. </p>
  
  <p>This output text file should be at precision of 20 decimal places and rounded to 20 decimal places.</p>
  
  <p>If an input value in excel is .005, my code converts it to 0.0050000000000000001 which is incorrect because of the very last digit.  It should be 0.0050000000000000000</p>
  
  <p>Here's my code: </p>
  
  <pre><code>dataFrame = pd.ExcelFile("xlFile.xlsx")
  pd.set_option("display.precision", 20)
  dataFrame.ColumnToRound = dataFrame.ColumnToRound.round(20)
  dataFrame.to_csv("out.txt", index=False, sep='\t', float_format='%.20f')
  </code></pre>
  
  <p>The INPUT excel file would look like this (just one column and one value for simplicity):</p>
  
  <p>ColumnToRound</p>
  
  <p>.005</p>
  
  <p>I have tried using the kwarg float_precision='round_trip' when reading the excel file using pandas.ExcelFile(), but it did not make a difference.  </p>
  
  <p>Side note: yes, I know 20 decimal places is a lot and probably more than necessary, but it was not my decision.  It has to be 20 decimal places.</p>