title: loop though excel files do something and save them to new folder python pandas
body: <p>I have am having trouble with a for loop.
  I dont know what happened, this used to work, but now it tells me "No objects to concatenate".</p>
  
  <p>I want to accomplish two things.
  I want to loop through all excel files in a folder. For each excel file I want to remove 2 lines of header data (which the code below already does). </p>
  
  <p>Then I want to save each edited file with its original file name in a new folder. But also, save a new file where all the data from each edited file is appended together.</p>
  
  <p>I thought I had the append correct but for some reason it is not working anymore.</p>
  
  <pre><code>import os
  import pandas as pd
  import numpy as np
  
  from pandas import Series, DataFrame
  
  appended_data = []
  
  path = 'C:\Test\TestRawFile'
  for fn in os.listdir(path):
      if os.path.isfile(fn):
          # Import the excel file and call it xlsx_file
          xlsx_file = pd.ExcelFile(fn)
          # View the excel files sheet names
          xlsx_file.sheet_names
          # Load the xlsx files Data sheet as a dataframe
          df = xlsx_file.parse('Sheet1',header= None)
          df_NoHeader = df[2:]
          data = df_NoHeader
          appended_data.append(data)
  appended_data = pd.concat(appended_data)
  </code></pre>
  
  <p>Here is the error I currently get.</p>
  
  <pre><code>---------------------------------------------------------------------------
  ValueError                                Traceback (most recent call last)
  &lt;ipython-input-46-962ccf280c0b&gt; in &lt;module&gt;()
       11         data = df_NoHeader
       12         appended_data.append(data)
  ---&gt; 13 appended_data = pd.concat(appended_data)
  
  C:\Anaconda2\lib\site-packages\pandas\tools\merge.pyc in concat(objs, axis, join, join_axes, ignore_index, keys, levels, names, verify_integrity, copy)
      832                        keys=keys, levels=levels, names=names,
      833                        verify_integrity=verify_integrity,
  --&gt; 834                        copy=copy)
      835     return op.get_result()
      836 
  
  C:\Anaconda2\lib\site-packages\pandas\tools\merge.pyc in __init__(self, objs, axis, join, join_axes, keys, levels, names, ignore_index, verify_integrity, copy)
      865 
      866         if len(objs) == 0:
  --&gt; 867             raise ValueError('No objects to concatenate')
      868 
      869         if keys is None:
  
  ValueError: No objects to concatenate
  </code></pre>