search
Search
Unlock 100+ guides
search toc
close
Cancel
Post
account_circle
Profile
exit_to_app
Sign out
What does this mean?
Why is this true?
Give me some examples!
search
keyboard_voice
close
Searching Tips
Search for a recipe:
"Creating a table in MySQL"
Search for an API documentation: "@append"
Search for code: "!dataframe"
Apply a tag filter: "#python"
Useful Shortcuts
/ to open search panel
Esc to close search panel
to navigate between search results
d to clear all current filters
Enter to expand content preview
Doc Search
Code Search Beta
SORRY NOTHING FOUND!
mic
Start speaking...
Voice search is only supported in Safari and Chrome.
Shrink
Navigate to

# Filling missing values (NaNs) with the mean of the column in Pandas DataFrame

schedule Aug 11, 2023
Last updated
local_offer
PythonPandas
Tags
expand_more
mode_heat
Master the mathematics behind data science with 100+ top-tier guides
Start your free 7-days trial now!

# Example

Consider the following DataFrame:

df = pd.DataFrame({"A":[np.nan,3,np.nan],"B":[4,np.nan,5],"C":[np.nan,7,8]}, index=["a","b","c"])
df
A B C
a NaN 4.0 NaN
b 3.0 NaN 7.0
c NaN 5.0 8.0

## Solution

To fill the missing values with the mean of the column:

df.fillna(df.mean())
A B C
a 3.0 4.0 7.5
b 3.0 4.5 7.0
c 3.0 5.0 8.0

Here, a new DataFrame is returned, and the original df is kept intact.

## Explanation

Here, df.mean() returns a Series that holds the mean of each column:

df.mean()
A 3.0
B 4.5
C 7.5
dtype: float64

Conveniently, this Series provides the mapping as to which value should be used as the filler for each column. We then directly use fillna(~) to perform the filling.

## Performing the fill in-place

The fillna(~) method allows for the filling to be performed in-place. Note that in-place means that the original DataFrame is directly modified, and no new DataFrame is returned.

Set inplace=True like so:

df.fillna(df.mean(), inplace=True)
df
A B C
a 3.0 4.0 7.5
b 3.0 4.5 7.0
c 3.0 5.0 8.0
Edited by 0 others
thumb_up
thumb_down
Comment
Citation
Ask a question or leave a feedback...
thumb_up
0
thumb_down
1
chat_bubble_outline
0
settings
Enjoy our search
Hit / to insta-search docs and recipes!