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

<class 'pandas.core.frame.DataFrame'>

 

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

 

 


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