Python | Pandas Index.append()

Python is an excellent language for data analysis, primarily because of the fantastic ecosystem of data-centric Python packages. Pandas are one of those packages, making importing and analyzing data much easier.

Pandas Index.append() The function is used to append a single or a collection of indices together. In the case of a collection of indices, all of them get appended to the original index in the same order as they are passed to the Index.append() function. The function returns an appended index.

Syntax:
Index.append(other)

Parameters :
other : Index or list/tuple of indices

Returns : Index

Example 1: Use Index.append() function to append a single index to the given index.

Python3

# importing pandas as pd
import pandas as pd

# Creating the first Index
df1 = pd.Index([17, 69, 33, 5, 0, 74, 0])

# Creating the second Index
df2 = pd.Index([11, 16, 54, 58])

# Print the first and second Index
print(df1, "\n", df2)

Output :

Int64Index([17, 69, 33, 5, 0, 74, 0], dtype='int64') 
Int64Index([11, 16, 54, 58], dtype='int64')

Let’s append the df2 index at the end of df1.

Python3

# append df2 at the end of df1
df1.append(df2)

Output :

 Int64Index([17, 69, 33, 5, 0, 74, 0, 11, 16, 54, 58], dtype='int64')

As we can see in the output, the second index i.e. df2 has been appended at the end of df1 .  

Example 2: Use Index.append() function to append a collection of indexes at the end of the given index.

Python3

# importing pandas as pd
import pandas as pd

# Creating the first Index
df1 = pd.Index(['Jan', 'Feb', 'Mar', 'Apr'])

# Creating the second Index
df2 = pd.Index(['May', 'Jun', 'Jul', 'Aug'])

# Creating the third Index
df3 = pd.Index(['Sep', 'Oct', 'Nov', 'Dec'])

# Print the first, second and third Index
print(df1, "\n", df2, "\n", df3)

Output :

Index(['Jan', 'Feb', 'Mar', 'Apr'], dtype='object') 
Index(['May', 'Jun', 'Jul', 'Aug'], dtype='object') 
Index(['Sep', 'Oct', 'Nov', 'Dec'], dtype='object')

Let’s append both the indexes df2 and df3 at the end of df1.

Python3

# We pass df2 and df3 as a list of
# indexes to the append function
df1.append([df2, df3])

Output :

Index(['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct',
       'Nov', 'Dec'],
      dtype='object')