title: Length of values does not match length of index when using pandas
body: <p>I'm getting 'ValueError: Length of values does not match length of index' while using Pandas.  I'm reading in data from an Excel spreadsheet using Pandas' 'pd.read_excel method. I then filter the data using Pandas' filter method.  I've created 'dataSubset' to represent the filtered data.  I use 'dataSubset' to create several 'mean' columns representing the mean of multiple columns respectively.  I then create 'finalData' which represents the pd.concat function concatenating all of the calculated mean columns together.  This code runs perfectly; however, if I uncomment any additional columns, the code blows up and gives the aformentioned error.</p>
  <p>What am I doing wrong?  It works as long as I don't concatenate more than it wants.</p>
  <p>Help.</p>
  <pre><code>import pandas as pd
  
  dataIn = pd.read_excel('IDT/IDT-B.xlsx')
  
  dataSubset = dataIn.filter([
      &quot;First Name&quot;,
      &quot;Last Name&quot;,
      &quot;2.14.2 Control Structures Example Quiz&quot;,
      &quot;2.14.4 Random Hurdles&quot;,
      &quot;2.15.2 Quiz: Which Control Structure?&quot;,
      &quot;2.16.2 How to Indent Your Code Quiz&quot;,
      &quot;2.16.4 Diagonal&quot;,
      &quot;2.16.5 Staircase&quot;,
      &quot;2.17.2 Debugging Basics&quot;,
      &quot;2.17.6 Debugging with Error Messages&quot;,
      &quot;3.2.6 Programming with Karel Quiz&quot;,
      &quot;5.1.2 Hello World Quiz&quot;,
      &quot;5.1.4 Your Name and Hobby&quot;,
      &quot;5.2.2 Variables Quiz&quot;,
      &quot;5.2.4 Daily Activities&quot;,
      &quot;5.3.2 User Input Quiz&quot;,
      &quot;5.3.4 Dinner Plans&quot;,
      &quot;5.4.2 Basic Math in JavaScript Quiz&quot;,
      &quot;5.4.6 T-Shirt Shop&quot;,
      &quot;5.4.7 Running Speed&quot;,
      &quot;5.5.2 JavaScript Graphics Quiz&quot;,
      &quot;5.5.8 Flag of the Netherlands&quot;,
      &quot;5.5.9 Snowman&quot;,
      &quot;5.6.2 Using RGB to Create Colors&quot;,
      &quot;5.6.4 Exploring RGB&quot;,
      &quot;5.6.5 Making Yellow&quot;,
      &quot;5.6.6 Rainbow&quot;,
      &quot;5.6.7 Create a Color Image!&quot;,
      &quot;6.1.1 Ghost&quot;,
      &quot;6.1.2 Fried Egg&quot;,
      &quot;6.1.3 Draw Something&quot;,
      &quot;6.1.4 JavaScript and Graphics Quiz&quot;
  
  ], axis=1)
  # If any of these dataframes are uncommented, the code blows up.
  
  # dataSubset['aver_2.14'] = dataSubset[[&quot;2.14.2 Control Structures Example Quiz&quot;,
  #                                       &quot;2.14.4 Random Hurdles&quot;]],
  # dataSubset['aver_2.15'] = dataSubset[[&quot;2.15.2 Quiz: Which Control Structure?&quot;]],
  # #
  # # dataSubset['aver_2.16'] = dataSubset[[&quot;2.16.2 How to Indent Your Code Quiz&quot;,
  # #                                       &quot;2.16.4 Diagonal&quot;]],
  # #
  # # dataSubset['aver_2.17'] = dataSubset[[&quot;2.17.2 Debugging Basics&quot;,
  # #                                       &quot;2.17.6 Debugging with Error Messages&quot;, ]]
  
  dataSubset['unit_quiz_326'] = dataSubset[[&quot;3.2.6 Programming with Karel Quiz&quot;]]
  
  dataSubset['aver_5.1'] = dataSubset[[&quot;5.1.2 Hello World Quiz&quot;,
                                      &quot;5.1.4 Your Name and Hobby&quot;]].mean(axis=1)
  
  dataSubset['aver_5.2'] = dataSubset[[&quot;5.2.2 Variables Quiz&quot;,
                                      &quot;5.2.4 Daily Activities&quot;]].mean(axis=1)
  
  dataSubset['aver_5.3'] = dataSubset[[&quot;5.3.2 User Input Quiz&quot;,
                                      &quot;5.3.4 Dinner Plans&quot;]].mean(axis=1)
  
  dataSubset['aver_5.4'] = dataSubset[[&quot;5.4.2 Basic Math in JavaScript Quiz&quot;,
                                      &quot;5.4.6 T-Shirt Shop&quot;,
                                      &quot;5.4.7 Running Speed&quot;]].mean(axis=1)
  
  dataSubset['aver_5.5'] = dataSubset[[&quot;5.5.2 JavaScript Graphics Quiz&quot;,
                                      &quot;5.5.8 Flag of the Netherlands&quot;,
                                      &quot;5.5.9 Snowman&quot;]].mean(axis=1)
  
  dataSubset['aver_5.6'] = dataSubset[[&quot;5.6.2 Using RGB to Create Colors&quot;,
                                      &quot;5.6.4 Exploring RGB&quot;,
                                      &quot;5.6.5 Making Yellow&quot;,
                                      &quot;5.6.6 Rainbow&quot;,
                                      &quot;5.6.7 Create a Color Image!&quot;]].mean(axis=1)
  
  dataSubset['aver_6.1'] = dataSubset[[&quot;6.1.1 Ghost&quot;,
                                      &quot;6.1.2 Fried Egg&quot;,
                                      &quot;6.1.3 Draw Something&quot;,
                                      &quot;6.1.4 JavaScript and Graphics Quiz&quot;]].mean(axis=1)
  
  finalData = pd.concat([dataSubset['First Name'],
                         dataSubset['Last Name'],
                         dataSubset['unit_quiz_326'],
                         # dataSubset['aver_2.14'],
                         # dataSubset['aver_2.15'],
                         # dataSubset['aver_2.16'],
                         # dataSubset['aver_2.17'],
                         dataSubset['aver_5.1'],
                         dataSubset['aver_5.2'],
                         dataSubset['aver_5.3'],
                         dataSubset['aver_5.4'],
                         dataSubset['aver_5.5'],
                         dataSubset['aver_5.6'],
                         dataSubset['aver_6.1']], axis=1)
  
  finalData.to_excel('output/gradesOut.xlsx')
  </code></pre>