Polyline Duplicate Neighbor Remover

Remove only consecutive exactly equal polyline vertices, retaining source indexes and nonadjacent repeats.

Description

Remove only consecutive exactly equal polyline vertices, retaining source indexes and nonadjacent repeats.

Removing consecutive duplicate points reduces zero-length segments while preserving later repeated locations.

When to use this tool

Remove only consecutive exactly equal polyline vertices, retaining source indexes and nonadjacent repeats.

Prepare the supplied points fields for this operation.
Compare the complete example with the representation used by your own input before carrying the result into another step.

How to use the tool and how it works

Enter points. Use the exact text syntax, units and index conventions explained below.
Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
Read result.points, result.sourceIndexes. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

Require x/y pairs, retain the first point and each subsequent point unequal to its immediate source predecessor, and return points with sourceIndexes.^[1]

Input field	Meaning and representation	Accepted input
points	points.	Numeric rows; at most 128 rows and 128 values per row

Output field	Interpretation
result	Object containing the named outputs below.
result.points	The points list in the ordering and representation described above.
result.sourceIndexes	Original input positions of the retained or selected records, under the ordering described above.

json

{
  "input": {
    "points": [
      [
        0,
        0
      ],
      [
        0,
        0
      ],
      [
        1,
        1
      ]
    ]
  },
  "output": {
    "result": {
      "points": [
        [
          0,
          0
        ],
        [
          1,
          1
        ]
      ],
      "sourceIndexes": [
        0,
        2
      ]
    }
  }
}

Limitations and assumptions

Equality is exact. Nonadjacent repeats remain, and no tolerance, closure or collinearity rule is applied.
Point pairs use [x,y], rectangles and viewBox use [x,y,width,height], and all coordinate units must be consistent. This tool does not read, render or modify an SVG document.
Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
String lists have at most 128 entries of at most 128 code units; matrices have at most 128 rows and columns. Larger numeric lists and parsed JSON have separate bounded budgets. Nonfinite results and excessively large serialized outputs are rejected.
Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.

Alternative or Complementary methods

Use a full SVG parser or rendering engine when the task includes commands and CSS values outside the documented branch. Compare coordinates and transforms under the same units and viewport convention.

References

Tool behavior and example: Polyline Duplicate Neighbor Remover — tool.io

Similar or alternative tools

Polyline Collinear Middle Pruner
Prune middle vertices lying within a supplied perpendicular distance of the enclosing segment and between endpoints; reversals are preserved.
Polyline Dash Span Planner
Plan clipped one-dimensional dash spans for an explicit dash/gap cycle and phase; not a complete SVG stroking or corner renderer.