title: Why do I get: "Length of values does not match length of index" error?
body: <p>I have the following code and I'm trying to assign <code>True</code> to a new Column where Actual Date equals the Date in Column 'D' (Date created) and <code>False</code> to any other.</p>
  
  <p>I'm quite new to Python so I would like to understand what I have done wrong:</p>
  
  <pre><code>def GetData():
      myList = GetFileList(TodaysDate,5)
      NewDataFrame  = pd.DataFrame()
      for x in myList:
          #The date of the actuals data is the day BEFORE it was created  
          ActualDate = getDate(x) - timedelta(days=1)
  
          myTempData = pd.read_csv(WSIWeatherDir + "\\" + x, parse_dates = [" date"], date_parser = DateTimeParser)
  
          myTempData = myTempData.replace(-99,np.nan)
          myTempData = myTempData.loc[myTempData['name'].isin(NL_WeatherStations)]
          myTempData['D'] = myTempData[' date'].dt.date
  
          #MyData = myTempData.sort([' date'], ascending=True)
          #print MyData
  
          #Select indices of the weather file where the column " date" is equal to the actual date we are looking for
          MyActualIndex = myTempData['D'] == ActualDate
          MyActualData = myTempData[MyActualIndex]
  
  
          MyExpectedIndex = myTempData.index.difference(MyActualData.index)
          MyExpectedData =  myTempData.loc[MyExpectedIndex] 
  
          myTempData ['Actuals'] = [True] * len(MyActualData.index)
          myTempData ['Actuals'] = [False] * len(MyExpectedData.index)
  
          NewDataFrame = pd.concat([NewDataFrame,myTempData])
      return NewDataFrame
  print GetData()
  </code></pre>
  
  <p>Error</p>
  
  <pre><code>runfile('C:/Users//Desktop/NLG_TAC_Calculation/TAC_2.py', wdir='C:/Users//Desktop/NLG_TAC_Calculation')
  Traceback (most recent call last):
  
    File "&lt;ipython-input-4-c9c151bca95a&gt;", line 1, in &lt;module&gt;
      runfile('C:/Users//Desktop/NLG_TAC_Calculation/TAC_2.py', wdir='C:/Users//Desktop/NLG_TAC_Calculation')
  
    File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 685, in runfile
      execfile(filename, namespace)
  
    File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 71, in execfile
      exec(compile(scripttext, filename, 'exec'), glob, loc)
  
    File "C:/Users//Desktop/NLG_TAC_Calculation/TAC_2.py", line 117, in &lt;module&gt;
      print GetData()
  
    File "C:/Users//Desktop/NLG_TAC_Calculation/TAC_2.py", line 108, in GetData
      myTempData ['Actuals'] = [True] * len(MyActualData.index)
  
    File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 2127, in __setitem__
      self._set_item(key, value)
  
    File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 2204, in _set_item
      value = self._sanitize_column(key, value)
  
    File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 2362, in _sanitize_column
      value = _sanitize_index(value, self.index, copy=False)
  
    File "C:\Python27\lib\site-packages\pandas\core\series.py", line 2579, in _sanitize_index
      raise ValueError('Length of values does not match length of '
  
  ValueError: Length of values does not match length of index
  </code></pre>