title: reading an xls in python
body: <p>I am currently trying to read an xls file in pandas with multiple worksheets(each month has 1 worksheet per day). I don't need all worksheets just the sheets that are named 1 to 31 depending on which month. How would I go about just joining only those dataframes into 1 data frame.</p>
  
  <p>I tried to hard-code the sheetnames in but got errors on days with only 28 or 30 days. 
  Is there a way to just read the sheetname if it is an int as the sheets I dont need are usually named 'Sheet1' etc</p>