Retrieve elements from the head and tail of a pandas DataFrame

Overview:

The first ‘n’ rows of a DataFrame can be selected using the instance method head(). The parameter ‘n’ specifies the number of rows to be present in the returned DataFrame.
Similarly, the tail() method of the DataFrame returns the last ‘n’ rows of a DataFrame as a separate DataFrame instance.
The default value for parameter 'n' in both the head() and tail() method is 5.
Similarly, to manipulate a pandas.series instance which is a one-dimensional container, the head() and tail() methods of the series class can be invoked.

Example – Retrieve first ‘n’ rows of a DataFrame using head() method:

# Example Python program that selects first 'n' rows of a DataFrame

# using the instance method head()

import pandas as pds

numRows2Select = 2;

# List of tuples

colorData = [("red", "blue", "green"),

("white", "grey", "black"),

("cyan", "purple", "brown")];

# Create a dataframe from a list of tuples

dataFrame = pds.DataFrame(colorData);

# Select first two rows of a DataFrame

firstFive = dataFrame.head(numRows2Select);

# Print the new DataFrame

print("First %d rows of a DataFrame selected using head():"%numRows2Select);

print(firstFive);

print(type(firstFive));

Output:

First 2 rows of a DataFrame selected using head():

0 1 2

0 red blue green

1 white grey black

Example – Retrieve last ‘n’ rows of a DataFrame using tail() method:

# Example Python program that selects last 'n' rows

# from a pandas DataFrame instance

import pandas as pds

# A list of tuples representing flight routes

routes = [("Dallas, Frankfurt, Singapore"),

("New York, London, Singapore"),

("Chicago, London, Bangkok"),

("San Francisco, Paris, Hong Kong"),

("Phoenix, Amsterdam, Seoul")];

# Create a DataFrame object

df = pds.DataFrame(routes, index=["R1", "R2", "R3", "R4", "R5"], columns=["Cities"]);

# Print the contents

print("The contents of the DataFrame:");

print(df);

# Print only the last two rows

print("Last 2 rows of the DataFrame selected using DataFrame.tail():");

print(df.tail(2));

Output:

The contents of the DataFrame:

Cities

R1 Dallas, Frankfurt, Singapore

R2 New York, London, Singapore

R3 Chicago, London, Bangkok

R4 San Francisco, Paris, Hong Kong

R5 Phoenix, Amsterdam, Seoul

Last 2 rows of the DataFrame selected using DataFrame.tail():

Cities

R4 San Francisco, Paris, Hong Kong

R5 Phoenix, Amsterdam, Seoul