df.assign()

df.assign(name_of_column=column_data)

Adds/replaces a column. name_of_column should not have quotes or spaces.

Input:

name_of_column : string

Name of column to assign list to.

column_data : list or Series

The data name_of_column will contain.

Returns:

A new DataFrame with name_of_column in addition to all the existing columns.

Return Type:

DataFrame

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pets = pets.assign(New_column_1=['this', 'is', 'a', 'new', 'column', 'I', 'assigned', '.'], 
                   New_column_2=['this', 'is', 'another', 'new', 'column', 'I', 'assigned', '.'])
pets

Index	ID	Species	Color	Weight	Age	Is_Cat	Owner_Comment	New_column_1	New_column_2
0	dog_001	dog	black	40	5	False	There are no bad dogs, only bad owners.	this	this
1	cat_001	cat	golden	1.5	0.2	True	My best birthday present ever!!!	is	is
2	cat_002	cat	black	15	9	True	****All you need is love and a cat.****	a	another
3	dog_002	dog	white	80	2	False	Love is a wet nose and a wagging tail.	new	new
4	dog_003	dog	black	25	0.5	False	Be the person your dog thinks you are.	column	column
5	ham_001	hamster	black	1	3	False	No, thank you!	I	I
6	ham_002	hamster	golden	0.25	0.2	False	No, thank you!	assigned	assigned
7	cat_003	cat	black	10	0	True	No, thank you!	.	.