title: How to use user-defined functions in python?
body: <p>I'm just learning python so be gentle. I want to read a file and that to be one function and then have another function work on what the previous function "read". I am having trouble passing the result on one function to another. Here is what I have no far:</p>
  
  <p>I want to call read_file more than once and to be able to pass its result to more than one function, therefore, I do not want frame to be a global variable. How do I get read_file to pass 'frame' to cost_channelID directly? Perhaps, for cost_channelID to call read_file?</p>
  
  <pre><code>def read_file():
      user_input = raw_input("please put date needed in x.xx form: ")
      path = r'C:\\Users\\CP\\documents\\' + user_input
      allFiles = glob.glob(path + '/*.csv')
      frame = pd.DataFrame()
      list = []
      for file in allFiles:
          df = pd.read_csv(file,index_col=None,header=0)
          list.append(df)
      frame =pd.concat(list,ignore_index=True)
  
  def cost_channelID():
      numbers =r'[0,1,2,3,4,5,6,7,8,9]'
      Ads = frame['Ad']
      ID = []
      for ad in Ads:
          num = ''.join(re.findall(numbers,ad)[1:7])
          ID.append(num)
      ID = pd.Series(ID)
      pieces = [frame,ID]
  
  
      frame2 = pd.concat(pieces,ignore_index=True,axis=1)
      frame2 = frame2.rename(columns={0:'Ad',1:'Ad Impressions',2:'Total Ad Spend',3:'eCPM (Total Ad Spend/Ad)',4:'Ad Attempts',5:'ID'})
  </code></pre>
  
  <p>Any and all help is greatly appreciated!</p>