dataframe 中的 For 循环，并将每次迭代保留在 Python 中

Question

I'm creating a template to process SurveyMonkey surveys into a Tableau ready format. I'm breaking down the surveys into their question types. I want to automate the script as much as possible so I'm trying to use a for loop for each question type.

For our purposes let's stick to the Ranking type question.

Let's say I have a dataframe like this:

d = {'Respondent ID': [123, 234, 345], 'rank question 1': [3, 5, 4], 'rank question 2': [1, 6, 7]}
df = pd.DataFrame(data=d)
df

I want the final dataframe to look like this:

rankfinal = {'Respondent ID': [123, 234, 345, 123, 234, 345], 'answer': [3, 5, 4, 1, 6, 7], 'question': ['rank question 1', 'rank question 1', 'rank question 1', 'rank question 2', 'rank question 2', 'rank question 2']}
rank1 = pd.DataFrame(data=rankfinal)
rank1

I've tried several attempts, but here is my best:

ranking = [1,2] # These are the column positions in the original survey dataframe

hold = [] 
for i in range(len(ranking)):
    hold.append(i)

respondent_id = []
questions = []
answers = []

for i in hold:
    if len(hold) < 1:
        print('No Ranking Questions! Moving on...')
    else:
        respondent_id.append(Respondent_ID)
        questions.append(df.columns[ranking[i]])
        answers.append(df.iloc[1:, ranking[i]])

While the code works, I don't think I can end up doing anything with the outputs to get them into a single dataframe. I've always struggled with loops so hopefully you might be able to help me get this project done.

Thanks in advance.

Answer 1

I would approach this problem by consolidating rank questions.

1. Loop through all "rank question" columns, and consolidate their values.

   • you will end up with a list [3, 5, 4, 1, 6, 7]

2. Duplicate Respondent ID field n times where n == num of "rank question" columns.

   • you will obtain a list [123, 234, 345, 123, 234, 345]

3. Create a list where you repeat "rank question" field names by the number of rows.

   • you will obtain a list [rank question 1, ..., rank question2, ...]

4. Finally assign these lists as json and pass to pandas Dataframe.

Answer 2

I worked out a solution I'm mostly happy with:

rank_fun = {}

if len(ranking) < 1:
    print('No Ranking Questions! Moving on...')
    
else:
    for i in ranking:
        rank_fun[i] = pd.concat([Respondent_ID, df.iloc[1:,i]], axis=1)
        rank_fun[i]['question'] = rank_fun[i].columns[1]

rank1 = pd.DataFrame()

for i in ranking:
    rank1 = rank_fun[i].append(rank_fun[i])
    
rank1.rename(columns={rank1.columns[1]: "answer" }, inplace = True)
rank1['answer option'] = "Rank"
rank1 = rank1[rank1['answer'].str.contains("nan")==False]

rank1

My only annoyance now is when there are no ranking questions I wish it wouldn't throw an error. Any ideas?