Convert dataframe of dictionary entries to dataframe of all entries based on existing dictionary

Question

I have a pandas dataframe that consists of an id and an associated count of different encoded words. For instance:

Original = pd.DataFrame(data=[[1,'1:2,2:3,3:1'],[2,'2:2,4:3']], columns=['id','words'])

I have a dictionary that has the mapping to the actual words, for instance:

WordDict = {1:'A',2:'B',3:'C',4:'D'}

What I would like to do is create a new dataframe that maps the counts to columns for all possible words, so it would look something like:

Final =pd.DataFrame(data=[[1,2,3,1,0],[2,0,2,0,3]], columns=['id','A','B','C','D']).set_index('id')

I know I can split the 'words' column of the original into separate columns, and can create a dataframe from WordDict so that it has all possible columns, but could not figure out how to create the mapping.

Answer 1

You can use a regex, a list comprehension, and the DataFrame constructor:

import re

Final = pd.DataFrame([{WordDict.get(int(k), None): v
                      for k,v in re.findall('([^:,]+):([^:,]+)', s)}
                      for s in Original['words']], index=Original['id']
                     ).fillna(0).astype(int)

Or with split:

Final = pd.DataFrame([{WordDict.get(int(k), None): v
                       for x in s.split(',')
                       for k,v in [x.split(':')]}
                      for s in Original['words']], index=Original['id']
                     ).fillna(0).astype(int)

Or ast.literal_eval:

from ast import literal_eval

Final = pd.DataFrame([{WordDict.get(k, None): v for k,v in literal_eval(f'{{{s}}}').items()}
                      for s in Original['words']], index=Original['id']
                     ).fillna(0, downcast='infer')

Output:

    A  B  C  D
id            
1   2  3  1  0
2   0  2  0  3