search
Search
Login
Map of Data Science
menu
menu search toc more_vert
Robocat
Guest 0reps
Sign up
Log in
account_circleMy Profile homeAbout paidPricing
emailContact us
exit_to_appLog out
Map of data science
Thanks for the thanks!
close
Comments
Log in or sign up
Cancel
Post
account_circle
Profile
exit_to_app
Sign out
help Ask a question
Share on Twitter
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
icon_star
Doc Search
icon_star
Code Search Beta
SORRY NOTHING FOUND!
mic
Start speaking...
Voice search is only supported in Safari and Chrome.
Navigate to
A
A
brightness_medium
share
arrow_backShare
Twitter
Facebook

Sorting values within groups in Pandas

Pandas
chevron_right
Cookbooks
chevron_right
DataFrame Cookbooks
chevron_right
Data Aggregation Cookbook
schedule Jul 1, 2022
Last updated
local_offer PythonPandas
Tags
map
Check out the interactive map of data science

Grouping by single column

Consider the following DataFrame:

df = pd.DataFrame({"A":[6,3,5,4],"B":[3,4,8,2],"group":["a","b","a","b"]})
df
A B group
0 6 3 a
1 3 4 b
2 5 8 a
3 4 2 b

Using sort_values method

To get the row with the smallest value for A in each group:

df.sort_values("A").groupby("group").head(1)
A B group
1 3 4 b
2 5 8 a

If you want the largest value instead, set ascending=False for sort_values(~).

Explanation

Here, we are first sorting df by column A using sort_values(~):

df.sort_values("A")   # ascending=True
A B group
1 3 4 b
3 4 2 b
2 5 8 a
0 6 3 a

We then group by column group, and fetch the first row of each group using head(1) (you could also use first()). This is guaranteed to work because groupby(~) preserves the ordering of the rows, that is, the order of the rows computed by sort_values(~) will be respected.

robocat
Published by Isshin Inada
Edited by 0 others
Did you find this page useful?
thumb_up
thumb_down
Ask a question or leave a feedback...
thumb_up
1
thumb_down
0
chat_bubble_outline
0
settings
Enjoy our search
Hit / to insta-search docs and recipes!