数据框列差异

Question

I have a data frame with 3 column FIRST, SECOND,THIRD. i want to find the difference of first column and combination of SECOND and THIRD. and create the values in Final column.

DF1=

   FIRST                         SECOND       THIRD

  "NEWYORK" IS NICE CITY             NICE      IS CITY
  "LONDON" WINTER MUCHBETTER         LONDON     WINTER                               
  "CANADA" IS EVEN MORECOLDER        CANADA     IS EVEN                          
  "PARIS" IS  MOREBEAUTIFUL      MOREBEAUTIFUL  IS   

i want my Data frame to to look like this:

DF1=

     FIRST                         SECOND       THIRD                            FINAL
  "NEWYORK" IS NICE CITY             NICE       IS CITY                            NEWYORK
  "LONDON" WINTER MUCHBETTER         LONDON     WINTER                             MUCHBETTER
  "CANADA" IS EVEN MORECOLDER        CANADA     IS EVEN                           MORECOLDER 
  "PARIS" IS  MOREBEAUTIFUL      MOREBEAUTIFUL    IS                                  PARIS

Answer 1

You can do this by:

import pandas as pd

# Creating the dataframe
columns = ['FIRST','SECOND','THIRD']
data = [
    ['NEWYORK IS NICE CITY', 'NICE', 'IS CITY'],
    ['LONDON WINTER MUCHBETTER', 'LONDON', 'WINTER'],
    ['CANADA IS EVEN MORECOLDER', 'CANADA', 'IS EVEN']
]

df = pd.DataFrame(data=data,columns=columns)

# Creating FINAL column
df['FINAL'] = df[['SECOND', 'THIRD']].agg(' '.join, axis=1).str.split(' ')
df['FINAL'] = df.apply(lambda x: ''.join(set(x['FIRST'].split(' ')) - set(x['FINAL'])), axis=1)

Here what is happening is that you are first creating the FINAL column joining the SECOND and THIRD columns. Then you create a set from the FIRST column splitted by space and subtract a set created from the recently created FINAL column, which will return a set with the only word contained in FIRST but not in SECOND or THIRD.

Then all you have to do is get a string from the set, using join.