Pandas Series.str.ljust() Method

The Series.str.ljust() method in in Python Pandas library is used to pad the right side of strings in a Series or Index to a specified minimum width.

This is equivalent to the string method str.ljust() in Python. The method ensures that each string in the Series or Index has at least the specified width, padding with a specified fill character if necessary.

Syntax

Following is the syntax of the Pandas Series.str.ljust() method −

Series.str.ljust(width, fillchar=' ')

Parameters

The Series.str.ljust() method accepts the following parameters −

• width − An integer specifying the minimum width of the resulting string. Additional characters will be filled with fillchar.

• fillchar − A string specifying the additional character for filling. The default is a whitespace character.

Return Value

The Series.str.ljust() method returns a Series or Index of objects with right-padded strings.

Example 1

In this example, we demonstrate the basic usage of the Series.str.ljust() method by right-padding the strings in a Series to a width of 8 using the fill character '.'.

import pandas as pd

# Create a Series of strings
s = pd.Series(['dog', 'lion', 'panda'])

# Display the input Series
print("Input Series")
print(s)

# Right-pad the strings 
print("Series after calling ljust with width=8 and fillchar='.'")
print(s.str.ljust(8, fillchar='.'))

When we run the above code, it produces the following output −

Input Series
0      dog
1     lion
2    panda
dtype: object

Series after calling ljust with width=8 and fillchar='.':
0    dog.....
1    lion....
2    panda...
dtype: object

Example 2

This example demonstrates how to use the Series.str.ljust() method to right-pad strings in a DataFrame's column to a width of 10 using the fill character '-'.

import pandas as pd

# Create a DataFrame
df = pd.DataFrame({'Animal': ['Python', 'Tutorial', 'panda'], 'Legs': [4, 4, 2]})

print("Input DataFrame:")
print(df)

# Right-pad the strings in the 'Animal' column 
df['Animal'] = df['Animal'].str.ljust(10, fillchar='-')

print("DataFrame after applying ljust with width=10 and fillchar='-':")
print(df)

Following is the output of the above code −

Input DataFrame:
     Animal  Legs
0    Python     4
1  Tutorial     4
2     panda     2

DataFrame after applying ljust with width=10 and fillchar='-':
      Animal  Legs
0    Python--     4
1  Tutorial-     4
2    panda---     2

Example 3

In this example, we apply the Series.str.ljust() method to right-pad the index labels of a DataFrame to a width of 10 using the fill character '*'.

import pandas as pd

# Create a DataFrame with an Index
df = pd.DataFrame({'Value': [1, 2, 3]}, index=['first', 'second', 'third'])

# Display the Input DataFrame
print("Input DataFrame:")
print(df)

# Right-pad the index labels of a DataFrame
df.index = df.index.str.ljust(10, fillchar='*')

# Display the Modified DataFrame
print("Modified DataFrame:")
print(df)

Output of the above code is as follows −

Input DataFrame:
        Value
first       1
second      2
third       3
Modified DataFrame:
            Value
first*****      1
second****      2
third*****      3