Python Pandas - Get integer location for requested label

To get the integer location for a requested label in Pandas, use the index.get_loc() method. This method returns the zero-based position of a label within the index.

Syntax

index.get_loc(key)

Parameters:

• key − The label for which to find the integer location

Basic Example

Let's create a Pandas index and find integer locations for specific labels ?

import pandas as pd

# Create Pandas index object
index = pd.Index(list('pqrstuvwxyz'))

# Display the Pandas index
print("Pandas Index...")
print(index)

# Get integer location from the given index
print("\nInteger location of 'w':", index.get_loc('w'))
print("Integer location of 'z':", index.get_loc('z'))
print("Integer location of 'p':", index.get_loc('p'))

Pandas Index...
Index(['p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'], dtype='object')

Integer location of 'w': 7
Integer location of 'z': 10
Integer location of 'p': 0

Using with DataFrame Index

The get_loc() method is commonly used with DataFrame row and column indexes ?

import pandas as pd

# Create a DataFrame with custom index
df = pd.DataFrame({
    'A': [10, 20, 30],
    'B': [40, 50, 60],
    'C': [70, 80, 90]
}, index=['row1', 'row2', 'row3'])

print("DataFrame:")
print(df)

# Get integer location of row labels
print("\nInteger location of 'row2':", df.index.get_loc('row2'))

# Get integer location of column labels  
print("Integer location of column 'B':", df.columns.get_loc('B'))

DataFrame:
      A   B   C
row1  10  40  70
row2  20  50  80
row3  30  60  90

Integer location of 'row2': 1
Integer location of column 'B': 1

Handling Non-Existent Labels

When a label doesn't exist in the index, get_loc() raises a KeyError ?

import pandas as pd

index = pd.Index(['a', 'b', 'c', 'd'])

try:
    location = index.get_loc('x')  # 'x' doesn't exist
    print("Location:", location)
except KeyError as e:
    print("KeyError:", e)
    
# Check if label exists before getting location
if 'b' in index:
    print("Location of 'b':", index.get_loc('b'))

KeyError: 'x'
Location of 'b': 1

Conclusion

The get_loc() method provides an efficient way to find the integer position of labels in Pandas indexes. Always handle potential KeyError exceptions when the label might not exist in the index.