title: TypeError: object of type 'method' has no len()
body: <pre><code>def DS():
  import os
  import pandas as pd
  
  directory=input('What folder would you like to work in? ( Example: /Users/hem/Desktop/pythontest/ ')
  filename=input('Please enter the name (including .csv) of the file you would like to analyze  ' ) 
  idkey=input('What is the subject ID you are analyzing?    '   )
  sessionkey=input('What session of testing are you analyzing?   ')      
  print('---------- Calculating Drug Stroop endpoints ----------')
  os.chdir(directory)
  dataframe = pd.read_csv(filename, error_bad_lines=False)
  output={}
  
  CategoryID = dataframe['CategoryID'].tolist
  ReactionTime = dataframe['ReactionTime'].tolist
  CorrectResponse = dataframe['CorrectResponse'].tolist
  
  #Stroop interference score
  totalN = 0
  countN = 0
  CorrectResponseNeutral = 0
  for i in range(len(CategoryID)):
      if CategoryID[i] == 1:
          totalN + ReactionTime[i]
          countN + 1
          CorrectResponseNeutral + CorrectResponse[i]
  
  AverageRTNeutral = totalN/countN  
  CorrectResponseNeutral = CorrectResponseNeutral/countN
  
  totalD = 0 
  countD = 0
  CorrectResponseDrug = 0
  for i in range(len(CategoryID)):
      if CategoryID[i] == 2:
          totalD + ReactionTime[i]
          countD + 1
          CorrectResponseDrug + CorrectResponse[i]
  
  AverageRTDrug = totalD/countD
  CorrectResponseDrug = CorrectResponseDrug/countD
  InterferenceScore =  AverageRTNeutral - AverageRTDrug       
  
  
  output['SubjectID'] = idkey 
  output['Session'] = sessionkey
  output['Interference Score'] = InterferenceScore
  output['Accuracy of Neutral Trials'] = CorrectResponseNeutral
  output['Accuracy of Drug Trials'] = CorrectResponseDrug
  print('---------- Done calculating endpoints ----------')
  outputname=input('What would you like to name your outputfile? (Please include.csv)')
  
  outputdataframe = pd.DataFrame.from_dict([output])
  outputdataframe.to_csv(os.path.join('/Users/hem/Desktop/Analysis/DrugStroopAnalyzed',outputname))
  </code></pre>
  
  <p>Hey Guys. Im trying to write a script that would calculate endpoints for a medical task. When I run the program, it works all the way until it hits the first for loop of the script. I'm pretty sure there is an error because CategoryID doesnt have a length property. But I also think it should because I'm converting it to a list in the beginning. Any suggestions on how to fix this? Thanks in advance.</p>