Get Number of Cases by Group in pandas DataFrame in Python (Example Code)
On this page you’ll learn how to count the number of cases by group in a pandas DataFrame in the Python programming language.
Setting up the Example
import pandas as pd # Import pandas library in Python |
import pandas as pd # Import pandas library in Python
my_df = pd.DataFrame({'A':range(19, 28), # Constructing a pandas DataFrame 'B':[6, 7, 3, 9, 1, 3, 8, 8, 9], 'C':range(20, 11, - 1), 'GRP_a':['gr1', 'gr1', 'gr2', 'gr3', 'gr1', 'gr2', 'gr2', 'gr3', 'gr3']}) print(my_df) # A B C GRP_a # 0 19 6 20 gr1 # 1 20 7 19 gr1 # 2 21 3 18 gr2 # 3 22 9 17 gr3 # 4 23 1 16 gr1 # 5 24 3 15 gr2 # 6 25 8 14 gr2 # 7 26 8 13 gr3 # 8 27 9 12 gr3 |
my_df = pd.DataFrame({'A':range(19, 28), # Constructing a pandas DataFrame 'B':[6, 7, 3, 9, 1, 3, 8, 8, 9], 'C':range(20, 11, - 1), 'GRP_a':['gr1', 'gr1', 'gr2', 'gr3', 'gr1', 'gr2', 'gr2', 'gr3', 'gr3']}) print(my_df) # A B C GRP_a # 0 19 6 20 gr1 # 1 20 7 19 gr1 # 2 21 3 18 gr2 # 3 22 9 17 gr3 # 4 23 1 16 gr1 # 5 24 3 15 gr2 # 6 25 8 14 gr2 # 7 26 8 13 gr3 # 8 27 9 12 gr3
Example: Number of Rows by Group in pandas DataFrame
print(my_df.groupby('GRP_a').size()) # Count rows by group column # GRP_a # gr1 3 # gr2 3 # gr3 3 # dtype: int64 |
print(my_df.groupby('GRP_a').size()) # Count rows by group column # GRP_a # gr1 3 # gr2 3 # gr3 3 # dtype: int64
Further Resources & Related Articles
Here, you can find some further resources on topics such as groups, counting, and dates:
- How to Count NaN in pandas DataFrame in Python
- Remove Rows with Empty Cells from pandas DataFrame in Python
- Ordering pandas DataFrame Rows by Multiple Columns in Python
- Get Top & Bottom N Rows of pandas DataFrame in Python
- Order Rows of pandas DataFrame by Date in Python
- Count Distinct Values by Group of pandas DataFrame Column in Python