Get a list of a specified column of a Pandas DataFrame
In this discussion, we’ll delve into the procedures involved in Get a list of a specified column of a Pandas DataFrame. Our journey commences with the essential task of importing data from a CSV file into a Pandas DataFrame. This initial step establishes the groundwork necessary to create an environment conducive to subsequent data manipulations.
Get a List of a specified column of a Pandas DataFrame
There are Various methods exist to Get a list of a specified column of a Pandas DataFrame. In this discussion, we will explore commonly employed techniques that are typically used to Get a list of a specified column of a Pandas DataFrame
- Using series.tolist()
- Using numpy.ndarray.tolist()
- Python list() Function
- ‘get()‘ Function in Python
- .iloc[] Function in Python
- List from Index column of Pandas Dataframe
Note: To get the CSV file used click here.
Create a simple DataFrame
The below code uses Pandas to read a CSV file (“nba.csv”) and creates a DataFrame. It then extracts the first five rows using the `head(5)` method, storing them in the variable `df`, and displays the resulting data.
Python3
import pandas as pd
data = pd.read_csv( "nba.csv" )
df = data.head( 5 )
df
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Output
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.
Get List from Pandas Dataframe 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
import pandas as pd
data = pd.read_csv( "nba.csv" )
df = data.head( 5 )
Name_list = df[ "Name" ].tolist()
print ( "Converting name to list:" )
Name_list
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Output:
Output
Let’s break it down and look at the types
Python3
print ( type (df[ "Name" ]))
print ( type (df[ "Name" ].values.tolist()
|
Output :
<class 'pandas.core.series.Series' >
<class 'list' >
Get List from Pandas Dataframe using numpy.ndarray.tolist()
With the help of numpy.ndarray.tolist(), 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
Name_list = df[ "Name" ].values.tolist()
print ( "Converting name to list:" )
Name_list
|
Output:
Output
Similarly, breaking it down
Python3
print ( type (df[ "Name" ].values))
print ( type (df[ "Name" ].values.tolist()
|
Output:
<class 'numpy.ndarray' >
<class 'list' >
Get List from Pandas Dataframe 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
Name_List = list (df[ "Name" ])
print ( "Converting name to list:" )
Name_List
|
Output:
Output
Get List from Pandas Dataframe using Get() Function in Python
In this method below code uses Pandas to create a sample DataFrame with individual details. It extracts the ‘Salary’ column using the ‘get()’ method, converting it into a Python list with ‘tolist()’, and prints both the original DataFrame and the ‘Salary’ values list. The ‘get()’ method proves useful for column retrieval in Pandas
Python3
data = { 'Name' : [ 'Geek1' , 'Geek2' , 'Geek3' ],
'Age' : [ 25 , 30 , 22 ],
'Salary' : [ 50000 , 60000 , 45000 ]}
df = pd.DataFrame(data)
salary_list = df.get( 'Salary' ).tolist()
print ( "Original DataFrame:" )
print (df)
print ( "\nList of 'Salary' column:" )
print (salary_list)
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Output :
Original DataFrame:
Name Age Salary
0 Alice 25 50000
1 Bob 30 60000
2 Charlie 22 45000
List of 'Salary' column:
[50000, 60000, 45000]
Get List from Pandas Dataframe using iloc() Function in Python
In this example the .iloc[]
function in Pandas is employed for integer-location based indexing. In the code snippet, df.iloc[:, 0]
selects all rows of the first column (‘Name’), converting it to a Python list using tolist()
. This approach provides a succinct means of extracting and handling data from the specified column based on integer positions in the DataFrame.
Python3
import pandas as pd
data = { 'Name' : [ 'Geek1' , 'Geek2' , 'Geek3' ],
'Team' : [ 'Celtics' , 'Celtics' , 'Celtics' ],
'Number' : [ 0 , 99 , 30 ],
'Position' : [ 'PG' , 'SF' , 'SG' ]}
df = pd.DataFrame(data)
name_column = df.iloc[:, 0 ].tolist()
print ( "List of the 'Name' column:" )
print (name_column)
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Output :
List of the 'Name' column:
['Geek1', 'Geek2', 'Geek3']
Get List from Index column of Pandas Dataframe
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
index_list = df.index.tolist()
print ( "Converting index to list:" )
index_list
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Output :
Converting index to list :
[0, 1, 2, 3, 4]
Last Updated :
01 Dec, 2023
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