title: Create a new dataframe based on rows with a certain value
body: <p>I have a large dataframe of transactions which I want to break into two smaller dataframes based on a certain column ("Type"). If "Type" is "S" then add that entire row to the "cust_sell" dataframe, and if "Type" is "P" to the "cust_buy" dataframe. I am using a for loop, but this is only adding the index value to the dataframe. Any help is appreciated!</p>
  
  <pre><code>from win32com.shell import shell, shellcon
  import pandas as pd
  
  filename = (shell.SHGetFolderPath(0, shellcon.CSIDL_PERSONAL, None, 0)) + '\MSRB T-1_test.xlsx'
  wb = pd.read_excel(filename, sheet_name='T1-20062017', index_col=0, header=0)
  cust_buy = []
  cust_sell = []
  
  # Create a list of customer buys and sells separately
  for i in wb.index:
      if wb['Type'][i] == 'S':
          cust_sell.append([i])
      elif wb['Type'][i] == 'P':
          cust_buy.append([i])
  </code></pre>