Python Pandas - Check if the interval is open on the left side

To check if an interval is open on the left side in Pandas, use the open_left property. An interval is "open" on the left when it excludes its left endpoint, meaning values equal to the left bound are not included in the interval.

Understanding Interval Types

Pandas intervals can be closed or open on either side using the closed parameter ?

import pandas as pd

# Different interval types
closed_both = pd.Interval(5, 20, closed='both')      # [5, 20] includes both endpoints
closed_left = pd.Interval(5, 20, closed='left')     # [5, 20) excludes right endpoint  
closed_right = pd.Interval(5, 20, closed='right')   # (5, 20] excludes left endpoint
closed_neither = pd.Interval(5, 20, closed='neither') # (5, 20) excludes both endpoints

print("Closed both:", closed_both)
print("Closed left:", closed_left)
print("Closed right:", closed_right) 
print("Closed neither:", closed_neither)

Closed both: [5, 20]
Closed left: [5, 20)
Closed right: (5, 20]
Closed neither: (5, 20)

Checking if Interval is Open on Left Side

Use the open_left property to determine if the left endpoint is excluded ?

import pandas as pd

# Create intervals with different closure types
interval1 = pd.Interval(5, 20, closed='both')    # Closed on left
interval2 = pd.Interval(5, 20, closed='right')   # Open on left
interval3 = pd.Interval(5, 20, closed='neither') # Open on left

print("Interval 1:", interval1)
print("Open on left:", interval1.open_left)
print()
print("Interval 2:", interval2) 
print("Open on left:", interval2.open_left)
print()
print("Interval 3:", interval3)
print("Open on left:", interval3.open_left)

Interval 1: [5, 20]
Open on left: False

Interval 2: (5, 20]
Open on left: True

Interval 3: (5, 20)
Open on left: True

Practical Example

Here's how to check interval properties including bounds and length ?

import pandas as pd

# Create an open interval
interval = pd.Interval(5, 20, closed='neither')

print("Interval:", interval)
print("Left bound:", interval.left)
print("Right bound:", interval.right)
print("Length:", interval.length)
print("Open on left:", interval.open_left)
print("Open on right:", interval.open_right)

Interval: (5, 20)
Left bound: 5
Right bound: 20
Length: 15
Open on left: True
Open on right: True

Summary

Conclusion

The open_left property returns True when an interval excludes its left endpoint. This is useful for mathematical operations and data filtering where endpoint inclusion matters.