How can I select the last few columns of a Python DataFrame?

Selecting the last few columns of a Python DataFrame using Pandas is straightforward. Here's how you can do it:

1. Using `iloc`:

The `iloc` method allows you to select data based on integer-based indexing. To select the last N columns, you can use negative indexing.

Here's an example:

import pandas as pd
# Create a sample DataFrame
data = {'col1': [1, 2, 3, 4, 5],
      'col2': [6, 7, 8, 9, 10],
      'col3': [11, 12, 13, 14, 15],
      'col4': [16, 17, 18, 19, 20],
      'col5': [21, 22, 23, 24, 25]}
df = pd.DataFrame(data)
# Select the last 3 columns
last_3_columns = df.iloc[:, -3:]
print(last_3_columns)


In this example, `df.iloc[:, -3:]` selects all rows (`:`) and the last 3 columns (`-3:`).

2. Using column names:

If you know the names of the last few columns or want to select columns based on a list of names, you can directly use the column names.

Example:

import pandas as pd
# Create a sample DataFrame
data = {'col1': [1, 2, 3, 4, 5],
      'col2': [6, 7, 8, 9, 10],
      'col3': [11, 12, 13, 14, 15],
      'col4': [16, 17, 18, 19, 20],
      'col5': [21, 22, 23, 24, 25]}
df = pd.DataFrame(data)
# Select columns 'col3', 'col4', and 'col5'
selected_columns = df[['col3', 'col4', 'col5']]
print(selected_columns)


This code selects the columns named 'col3', 'col4', and 'col5'.

3. Dynamically Identifying Column Names:

If you need to select the last N columns but don't know their names in advance, you can get the column names dynamically.

Example:

import pandas as pd
# Create a sample DataFrame
data = {'col1': [1, 2, 3, 4, 5],
      'col2': [6, 7, 8, 9, 10],
      'col3': [11, 12, 13, 14, 15],
      'col4': [16, 17, 18, 19, 20],
      'col5': [21, 22, 23, 24, 25]}
df = pd.DataFrame(data)
# Number of last columns to select
n = 3
# Get the names of the last n columns
last_n_columns_names = df.columns[-n:]
# Select the last n columns
last_n_columns = df[last_n_columns_names]
print(last_n_columns)


Here, `df.columns[-n:]` retrieves the column names of the last N columns, and then `df[last_n_columns_names]` selects these columns.

These methods provide flexible ways to select the last few columns of a Python DataFrame, depending on whether you need to use integer-based indexing or column names.

Learn more about this