In this article, we will discuss how to get a list of specified column of a Pandas Dataframe. First, we will read a csv file into a pandas dataframe.
Note: To get the CSV file used click here.
Example:
Python3
# importing pandas module import pandas as pd # making data frame from csv data = pd.read_csv("nba.csv") # calling head() method df = data.head(5) # displaying data df |
Output:
Let’s see how to get a list of a specified column of a Pandas DataFrame:
We will convert the column “Name” into a list using three different ways.
1. Using Series.tolist()
From the dataframe, we select the column “Name” using a [] operator that returns a Series object. Next, we will use the function Series.to_list() provided by the Series class to convert the series object and return a list.
Python3
# importing pandas module import pandas as pd # making data frame from csv data = pd.read_csv("nba.csv") df = data.head(5) # Converting a specific Dataframe # column to list using Series.tolist() Name_list = df["Name"].tolist() print("Converting name to list:") # displaying list Name_list |
Output:
Let’s break it down and look at the types
Python3
# column 'Name' as series object print(type(df["Name"])) # Convert series object to a list print(type(df["Name"].values.tolist() |
Output:
2. Using numpy.ndarray.tolist()
From the dataframe we select the column “Name” using a [] operator that returns a Series object and uses Series.Values to get a NumPy array from the series object. Next, we will use the function tolist() provided by NumPy array to convert it to a list.
Python3
# importing pandas module import pandas as pd # making data frame from csv data = pd.read_csv("nba.csv") df = data.head(5) # Converting a specific Dataframe column # to list using numpy.ndarray.tolist() Name_list = df["Name"].values.tolist() print("Converting name to list:") # displaying list Name_list |
Output:
Similarly, breaking it down
Python3
# Select a column from dataframe # as series and get a numpy array print(type(df["Name"].values)) # Convert numpy array to a list print(type(df["Name"].values.tolist() |
Output:
3. Using Python list() function
You can also use the Python list() function with an optional iterable parameter to convert a column into a list.
Python3
# importing pandas module import pandas as pd # making data frame from csv data = pd.read_csv("nba.csv") df = data.head(5) # Converting a specific Dataframe # column to list using list() # function in Python Name_List = list(df["Name"]) print("Converting name to list:") # displaying list Name_List |
Output:
Converting index column to list
Index column can be converted to list, by calling pandas.DataFrame.index which returns the index column as an array and then calling index_column.tolist() which converts index_column into a list.
Python3
# Converting index column to list index_list = df.index.tolist() print("Converting index to list:") # display index as list index_list |
Output:
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