Suppose you have a Pandas DataFrame consisting of 2 columns and we want to group these columns. In this article, we will discuss the same.
Creating Dataframe to group Dataframe rows into a list
Python3
# importing pandas as pdimport pandas as pd# Create the data framedf = pd.DataFrame({'column1': ['A', 'B', 'C', 'A', 'C', 'C', 'B', 'D', 'D', 'A'], 'column2': [5, 10, 15, 20, 25, 30, 35, 40, 45, 50]})# Print the dataframedf |
Output:
Group rows into a list in Pandas using apply()
We can use groupby() method on column 1 and apply the method to apply a list on every group of pandas DataFrame.
Python3
# importing pandas as pdimport pandas as pd# Create the data framedf = pd.DataFrame({'column1': ['A', 'B', 'C', 'A', 'C', 'C', 'B', 'D', 'D', 'A'], 'column2': [5, 10, 15, 20, 25, 30, 35, 40, 45, 50]})# Use groupby method and apply# method on the dataframedf = df.groupby('column1')['column2'].apply(list)# Print the dataframe againdf |
Output:
Group rows into a list in Pandas using lambda
We can use groupby() method on column 1 and agg() method to apply aggregation, consisting of the lambda function, on every group of pandas DataFrame.
Python3
# importing pandas as pdimport pandas as pd# Create the dataframedf = pd.DataFrame({'column1': ['A', 'B', 'C', 'A', 'C', 'C', 'B', 'D', 'D', 'A'], 'column2': [5, 10, 15, 20, 25, 30, 35, 40, 45, 50]})# Use groupby method and agg method# with lambda function on the dataframedf = df.groupby('column1').agg({'column2': lambda x: list(x)})# Print the dataframe againdf |
Output:
Group rows into a list in Pandas using agg()
We can use the groupby() method on column1, and agg() method to apply the aggregation list, on every group of pandas DataFrame.
Python3
# importing pandas as pdimport pandas as pd# Create the data framedf = pd.DataFrame({'column1': ['A', 'B', 'C', 'A', 'C', 'C', 'B', 'D', 'D', 'A'], 'column2': [5, 10, 15, 20, 25, 30, 35, 40, 45, 50]})# Use groupby method and agg method# with list as argument on the dataframedf = df.groupby('column1').agg(list)df |
Output:
Group rows into a list in Pandas using Pandas tolist
We can use groupby() method on column 1 and agg() method by passing ‘pd.Series.tolist’ as an argument.
Python3
# importing pandas as pdimport pandas as pd# Create the data framedf = pd.DataFrame({'column1': ['A', 'B', 'C', 'A', 'C', 'C', 'B', 'D', 'D', 'A'], 'column2': [5, 10, 15, 20, 25, 30, 35, 40, 45, 50]})# Use groupby method and agg method with# pd.Series.tolist as argument on the dataframedf = df.groupby('column1').agg(pd.Series.tolist)df |
Output:
