title: Pandas ExcelFile read columns as string
body: <p>I know that you can specify data types when reading excels using <code>pd.read_excel</code> (as outlined <a href="https://stackoverflow.com/questions/32591466/python-pandas-how-to-specify-data-types-when-reading-an-excel-file">here</a>). Can you do the same using <code>pd.ExcelFile</code>?</p>
  
  <p>I have the following code:</p>
  
  <pre><code> if ".xls" in 
       xl = pd.ExcelFile(path + "\\" + name, )
       for sheet in xl.sheet_names:
           xl_parsed = xl.parse(sheet)
  </code></pre>
  
  <p>When parsing the sheet, some of the values in the columns are displayed in scientific notation. I don't know the column names before loading so I need to import everything as string. Ideally I would like to be able to do something like <code>xl_parsed = xl.parse(sheet, dtype = str)</code>. Any suggestions?</p>