count multiple value in dataframe

Question

I have a data frame that shows answers of a multiple-choice question of 5 students:

id     Question 1

0          a;b;c

1          a;c

2          b

3          a;d

4          b;c;d

And I want to count how many times does a choice been selected. For example, the final answer should be

a:3

b:3

c:3

d:2 

So is there a quick way to get the solution using python?

Besides, I am using the data from the data frame for visualization in Tableau. Tableau counts like this: 

a;b;c appear once

a;c   appear once

b     appear once

a;d   appear once

b;c;d appear once

So is there a way to get the above result directly using Tableau? Or I have to do something in python then using tableau.

Thanks 

Answer 1

Try the following code to count the occurrence of each choice in a pandas dataframe column:

data = pd.DataFrame({'id':[0, 1,2,3,4], 'Question1':['a;b;c','a;c','b','a;d','b;c;d']})

count = data.Question1.str.split(';', expand=True).stack().value_counts()

Output:

a    3

b    3

c    3

d    2

dtype: int64