Assign a list to part of a column python

Question

df1 has shape 4 column with 5 rows, and df2 has shape 2 columns with 7 rows.

I need to assign 1 column consisting of 10 rows into df2 consisting of 7 rows. , starting at index 1. df1

  First Name      last Name         
1. John          Smith              
2. Mary          Brohowski           
3. Aristidis     Papageorgopoulos   
4. James         Watss               
5. Kid           Red

df2

 First Name     Last Name   
0. Marty          Smith
1. Sandy          Kevin          
2. Parry          Brohowski      
3. May            Dave      
4. Manny          Garido         
5. Rudy           Red         
6. Wesley         Rednap         
7. Ben            Papageo

how can i change rows 1:5 in First Name column in df2, starting with index 0 with df1 Name column, starting with column 1 so the out put will be :

df2

   First Name     Last Name   
0. Marty          Smith          
1. John           Kevin          
2. Mary           Brohowski      
3. Aristidis      Dave          
4. James          Garido     
5. Kid            Red
6. Wesley         Rednap         
7. Ben            Papageo

ive tried:

df1 = df1.reset_index()

start_row = 1
i = 1
for i in range(start_row, len(df2)-1):

    while i < len(df2):
        df2[i] = df1[i]
    else:
        break

any help pls

do thuan · Accepted Answer · 2019-12-01 15:58:56Z

2

Try merge to merge to dataframe.

new_df = df1.merge(left_on='Last Name', right_on='Last Name', how='left')

answered Dec 1, 2019 at 15:58

do thuan

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Comments

anky · Accepted Answer · 2019-12-01 15:59:09Z

2

You can do a combine_first() after selecting the First Name column as a dataframe:

df1[['First Name']].combine_first(df2)

  First Name  Last Name
0      Marty      Smith
1       John      Kevin
2       Mary  Brohowski
3  Aristidis       Dave
4      James     Garido
5        Kid        Red
6     Wesley     Rednap
7        Ben    Papageo

answered Dec 1, 2019 at 15:59

anky

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5 Comments

Jienkles Over a year ago

Great solution @anky_91, i have another situation to reproduce where df1['Person'] is the column instead of 'First Name' and i need to leave it as 'Person'. How would that work?

anky Over a year ago

@Jienkles do you mean something like: df1[['First Name']].combine_first(df2).rename(columns={'First Name':'Person'}) ?

anky Over a year ago

Or same way you can rename df2 first name to person and then do combine first. df1[['Person']].combine_first(df2.rename(columns={'First Name' :'Person' }))

Jienkles Over a year ago

@anky_91 how can i do the same thing but paste into a row from df2? grateful for your help

anky Over a year ago

@Jienkles i am not clear with the question, but did you try swapping the df1 and df2 in the combine first? If yes, what is your expected result?

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