Clustering Number

Purpose

This note defines the two-digit Numeric Suffix used to group related survey records that may not be consecutive in the point-number sequence.

Source Priority

1. HAPI User Manual.pdf
2. HAPI Quick Start Guide.pdf
3. Point Code and Style Code.md

Definition

A Clustering Number is a two-digit Numeric_Suffix appended after a Feature_Code. It establishes an explicit logical link between related survey points.

Syntax

FeatureCode + ClusteringNumber

Examples:

Business Rules

Preserve Leading Zeroes

The clustering token should be treated as a string token, not merely an integer.

01 ≠ visually equivalent to 1 for diagnostic and grouping traceability

Linear Features

For LINEAR features, a Clustering Number overrides default sequential grouping. All points sharing the same Feature Code and Clustering Number are connected into a single continuous feature, even if interrupted by unrelated Point Codes.

Polygonal Features

For POLYGON features, a Clustering Number changes the behaviour from rectangular calculation to irregular polygon enclosure. All points sharing the same Feature Code and Clustering Number are grouped into one polygonal feature.

Feature Separation

A change in Clustering Number explicitly separates features even if the Feature Code remains the same.

Examples

Implementation Notes

Preferred planned functions:

• ResolveClusteringNumber
• GroupLinearRecordsByCluster
• GroupPolygonRecordsByCluster
• BuildClusterKey

A stable grouping key should include at least:

FeatureCode + ClusteringNumber

For curve-aware linear features, the grouping key may need to resolve straight and curve variants into a common base identity.

Related Notes

• Numeric_Suffix
• Point_Code_Grouping_Rules
• Segment_Type_Indicator
• Supplementary_Suffix

Open Questions

• Confirm whether cluster grouping should use raw Feature Code variants (KX and KC) or resolved base feature identity for curve-capable features.