Replace all non-empty strings in a column with a constant

Question

I have a data frame with a variety of string values. For a given column, if there is any string entered, I would like to replace it with the same value (say 'fruit').

Example:

data = {'item_name': ['apple', 'banana', 'cherry', 'pineapple', 'apple pie', 'banana split', 'hafts to chos', 'lov_frutz', 'I always pick apples', None, None, None]}
df = pd.DataFrame(data)

Result I want:

item_name
'fruit'
'fruit'
'fruit'
'fruit'
'fruit'
'fruit'
'fruit'
'fruit'
'fruit'
nan
nan
nan

response = 'fruit'

I have tried using regex but don't seem to understand it correctly, so tried:

df[col] = df[col].replace(to_replace=r'\w\b', value = response, regex = True)

Try df.loc[df["item_name"].notna(), "item_name"] = "fruit". — Timus
– Timus, Commented Jul 15 at 17:24

PaulS · Accepted Answer · 2025-07-15 22:52:26Z

4

Another possible solution, which uses where and isnull as its condition:

df.where(df.isnull(), "Fruit")

Output:

   item_name
0      Fruit
1      Fruit
2      Fruit
3      Fruit
4      Fruit
5      Fruit
6      Fruit
7      Fruit
8      Fruit
9       None
10      None
11      None

answered Jul 15 at 22:52

PaulS

27.1k3 gold badges19 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Replace all non-empty strings in a column with a constant

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related