title: Import multiple excel files into python pandas and concatenate them into one dataframe
body: <p>I would like to read several excel files from a directory into pandas and concatenate them into one big dataframe. I have not been able to figure it out though. I need some help with the for loop and building a concatenated dataframe:
  Here is what I have so far: </p>
  
  <pre><code>import sys
  import csv
  import glob
  import pandas as pd
  
  # get data file names
  path =r'C:\DRO\DCL_rawdata_files\excelfiles'
  filenames = glob.glob(path + "/*.xlsx")
  
  dfs = []
  
  for df in dfs: 
      xl_file = pd.ExcelFile(filenames)
      df=xl_file.parse('Sheet1')
      dfs.concat(df, ignore_index=True)
  </code></pre>