Pandas Series.append()

Pandas Series.append() Method

The Series.append() method in pandas is used to concatenate two or more Series objects, returning a new Series object. This method is particularly useful when you need to combine multiple Series or add new rows to an existing Series.

Syntax

Series.append(to_append, ignore_index=False, verify_integrity=False)

Parameters:

• to_append: Series, or list/tuple of Series. The Series to append to the original Series.
• ignore_index: bool, default False. If True, do not use the index labels. The resulting Series will have a new integer index.
• verify_integrity: bool, default False. If True, checks whether the new concatenated axis contains duplicates. Raises ValueError if duplicates are found.

Example 1: Appending One Series to Another

Consider two Series:

import pandas as pd

# Creating the first Series
sr1 = pd.Series(['New York', 'Chicago', 'Toronto', 'Lisbon', 'Rio'])

# Creating the second Series
sr2 = pd.Series(['Chicago', 'Shanghai', 'Beijing', 'Jakarta', 'Seoul'])

# Appending sr2 to sr1
result = sr1.append(sr2, ignore_index=True)

print(result)

Output:

0       New York
1        Chicago
2        Toronto
3         Lisbon
4            Rio
5        Chicago
6       Shanghai
7        Beijing
8        Jakarta
9          Seoul
dtype: object

In this example, sr2 is appended to sr1, and the ignore_index=True parameter ensures that the index is reset in the resulting Series.

Example 2: Appending a List to a Series

You can also append a list to a Series:

import pandas as pd

# Creating a Series
sr1 = pd.Series(['New York', 'Chicago', 'Toronto'])

# Creating a list
new_data = ['Lisbon', 'Rio']

# Appending the list to the Series
sr1 = sr1.append(pd.Series(new_data), ignore_index=True)

print(sr1)

Output:

0      New York
1       Chicago
2       Toronto
3        Lisbon
4           Rio
dtype: object

Here, a list of new data is converted to a Series and appended to sr1.

Example 3: Appending a Dictionary as a Row

If you have a dictionary and want to append it as a new row:

import pandas as pd

# Creating a Series
sr1 = pd.Series(['New York', 'Chicago', 'Toronto'])

# Creating a dictionary
new_data = {'0': 'Lisbon', '1': 'Rio'}

# Appending the dictionary to the Series
sr1 = sr1.append(pd.Series(new_data), ignore_index=True)

print(sr1)

Output:

0      New York
1       Chicago
2       Toronto
3        Lisbon
4           Rio
dtype: object

In this case, the dictionary is converted to a Series and appended to sr1.

Important Notes

• The append() method does not modify the original Series; it returns a new Series with the appended data.
• As of pandas version 2.0, the append() method has been removed. It is recommended to use pd.concat() for appending data to a Series.

Conclusion

The Series.append() method is a convenient way to add data to a Series. However, with its removal in pandas 2.0, transitioning to pd.concat() is advisable for future-proofing your code. Understanding these methods enhances your ability to manipulate and analyze data efficiently in pandas.