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Computational Geometry with Shapely · vibeeval | DecimalAI

Shapely Compute

SkillScore77Maintained

shapely-compute

Computational geometry with Shapely - create geometries, boolean operations, measurements, predicates

codingby vibeeval

Links this skill to your agents and keeps it current with the author’s updates.

Automatic

Coding pack

1 · One-time — install the CLI (docs ↗)

pip install decimalai

2 · Get the skill — writes .claude/skills/shapely-compute/SKILL.md

decimalai skills pull shapely-compute --out .claude/skills/

No CLI? Get the same file — curl · raw file

curl -fsSL --create-dirs -o .claude/skills/shapely-compute/SKILL.md https://app.decimal.ai/s/shapely-compute/SKILL.md

Raw file: /s/shapely-compute/SKILL.md ↗ · machine-readable summary at /s/shapely-compute.json ↗

In productionGlobal

how this skill behaves on real traffic · last 30 days

No production data for this skill yet — usage numbers appear here once agents start running it.

Anonymized aggregate across every org using this skill — proof from real production use, not a demo.

Does this skill help? · Benchmark: with vs. withoutsign in to run this on your agents

22 test cases from the publisher’s eval.yaml · each run twice on gemini-3.6-flash — with the skill injected, then without · last run 51d ago

—+107% tokens0% turns77% of whole cases pass with skill (17/22)

Test case	Without → With	Effect	Δ tokens	Δ turns
case-04	✗→✓	▲ Improved	17%	0%
case-05	✗→✓	▲ Improved	61%	0%
case-06	✗→✓	▲ Improved	54%	0%
case-08	✗→✓	▲ Improved	119%	0%
case-12	✗→✓	▲ Improved	65%	0%

Showing 5 of 22 cases

SkillSafety

✓ 3 of 3 passed

Code scan15 of 15 checks clean

0 critical · 0 warning · 0 info — scanner v4 — 8/1/2026

live_secretremote_code_executionreverse_shelldata_exfiltrationssrf_metadataagent_snoopinganti_refusaldestructive_commandsobfuscated_unicodeunicode_homoglyphopaque_blobsuspicious_urltool_overreachtrigger_abuseprompt_injection_phrasing

IntentSafe

LLM judge · does the skill do what it claims

ContentClean

LLM judge · policy & harmful-content review

Source

Imported

vibeeval / vibecosystem

skills/shapely-compute/SKILL.md

View on GitHub ↗

License MITImported 8/1/2026Version v2

Skill contents

SKILL.md

Computational Geometry with Shapely

When to Use

Creating geometric shapes (points, lines, polygons)
Boolean operations (intersection, union, difference)
Spatial predicates (contains, intersects, within)
Measurements (area, length, distance, centroid)
Geometry transformations (translate, rotate, scale)
Validating and fixing invalid geometries

Quick Reference

| I want to... | Command | Example | |--------------|---------|---------| | Create geometry | create | create polygon --coords "0,0 1,0 1,1 0,1" | | Intersection | op intersection | op intersection --g1 "POLYGON(...)" --g2 "POLYGON(...)" | | Check contains | pred contains | pred contains --g1 "POLYGON(...)" --g2 "POINT(0.5 0.5)" | | Calculate area | measure area | measure area --geom "POLYGON(...)" | | Distance | distance | distance --g1 "POINT(0 0)" --g2 "POINT(3 4)" | | Transform | transform translate | transform translate --geom "..." --params "1,2" | | Validate | validate | validate --geom "POLYGON(...)" |

Commands

create

Create geometric objects from coordinates.

bash
# Point
uv run python scripts/shapely_compute.py create point --coords "1,2"

# Line (2+ points)
uv run python scripts/shapely_compute.py create line --coords "0,0 1,1 2,0"

# Polygon (3+ points, auto-closes)
uv run python scripts/shapely_compute.py create polygon --coords "0,0 1,0 1,1 0,1"

# Polygon with hole
uv run python scripts/shapely_compute.py create polygon --coords "0,0 10,0 10,10 0,10" --holes "2,2 8,2 8,8 2,8"

# MultiPoint
uv run python scripts/shapely_compute.py create multipoint --coords "0,0 1,1 2,2"

# MultiLineString (pipe-separated lines)
uv run python scripts/shapely_compute.py create multilinestring --coords "0,0 1,1|2,2 3,3"

# MultiPolygon (pipe-separated polygons)
uv run python scripts/shapely_compute.py create multipolygon --coords "0,0 1,0 1,1 0,1|2,2 3,2 3,3 2,3"

op (operations)

Boolean geometry operations.

bash
# Intersection of two polygons
uv run python scripts/shapely_compute.py op intersection \
    --g1 "POLYGON((0 0,2 0,2 2,0 2,0 0))" \
    --g2 "POLYGON((1 1,3 1,3 3,1 3,1 1))"

# Union
uv run python scripts/shapely_compute.py op union --g1 "POLYGON(...)" --g2 "POLYGON(...)"

# Difference (g1 - g2)
uv run python scripts/shapely_compute.py op difference --g1 "POLYGON(...)" --g2 "POLYGON(...)"

# Symmetric difference (XOR)
uv run python scripts/shapely_compute.py op symmetric_difference --g1 "..." --g2 "..."

# Buffer (expand/erode)
uv run python scripts/shapely_compute.py op buffer --g1 "POINT(0 0)" --g2 "1.5"

# Convex hull
uv run python scripts/shapely_compute.py op convex_hull --g1 "MULTIPOINT((0 0),(1 1),(0 2),(2 0))"

# Envelope (bounding box)
uv run python scripts/shapely_compute.py op envelope --g1 "POLYGON(...)"

# Simplify (reduce points)
uv run python scripts/shapely_compute.py op simplify --g1 "LINESTRING(...)" --g2 "0.5"

pred (predicates)

Spatial relationship tests (returns boolean).

bash
# Does polygon contain point?
uv run python scripts/shapely_compute.py pred contains \
    --g1 "POLYGON((0 0,2 0,2 2,0 2,0 0))" \
    --g2 "POINT(1 1)"

# Do geometries intersect?
uv run python scripts/shapely_compute.py pred intersects --g1 "..." --g2 "..."

# Is g1 within g2?
uv run python scripts/shapely_compute.py pred within --g1 "POINT(1 1)" --g2 "POLYGON(...)"

# Do geometries touch (share boundary)?
uv run python scripts/shapely_compute.py pred touches --g1 "..." --g2 "..."

# Do geometries cross?
uv run python scripts/shapely_compute.py pred crosses --g1 "LINESTRING(...)" --g2 "LINESTRING(...)"

# Are geometries disjoint (no intersection)?
uv run python scripts/shapely_compute.py pred disjoint --g1 "..." --g2 "..."

# Do geometries overlap?
uv run python scripts/shapely_compute.py pred overlaps --g1 "..." --g2 "..."

# Are geometries equal?
uv run python scripts/shapely_compute.py pred equals --g1 "..." --g2 "..."

# Does g1 cover g2?
uv run python scripts/shapely_compute.py pred covers --g1 "..." --g2 "..."

# Is g1 covered by g2?
uv run python scripts/shapely_compute.py pred covered_by --g1 "..." --g2 "..."

measure

Geometric measurements.

bash
# Area (polygons)
uv run python scripts/shapely_compute.py measure area --geom "POLYGON((0 0,1 0,1 1,0 1,0 0))"

# Length (lines, polygon perimeter)
uv run python scripts/shapely_compute.py measure length --geom "LINESTRING(0 0,3 4)"

# Centroid
uv run python scripts/shapely_compute.py measure centroid --geom "POLYGON((0 0,2 0,2 2,0 2,0 0))"

# Bounds (minx, miny, maxx, maxy)
uv run python scripts/shapely_compute.py measure bounds --geom "POLYGON(...)"

# Exterior ring (polygon only)
uv run python scripts/shapely_compute.py measure exterior_ring --geom "POLYGON(...)"

# All measurements at once
uv run python scripts/shapely_compute.py measure all --geom "POLYGON((0 0,2 0,2 2,0 2,0 0))"

distance

Distance between geometries.

bash
uv run python scripts/shapely_compute.py distance --g1 "POINT(0 0)" --g2 "POINT(3 4)"
# Returns: {"distance": 5.0, "g1_type": "Point", "g2_type": "Point"}

transform

Affine transformations.

bash
# Translate (move)
uv run python scripts/shapely_compute.py transform translate \
    --geom "POLYGON((0 0,1 0,1 1,0 1,0 0))" --params "5,10"
# params: dx,dy or dx,dy,dz

# Rotate (degrees, around centroid by default)
uv run python scripts/shapely_compute.py transform rotate \
    --geom "POLYGON((0 0,1 0,1 1,0 1,0 0))" --params "45"
# params: angle or angle,origin_x,origin_y

# Scale (from centroid by default)
uv run python scripts/shapely_compute.py transform scale \
    --geom "POLYGON((0 0,1 0,1 1,0 1,0 0))" --params "2,2"
# params: sx,sy or sx,sy,origin_x,origin_y

# Skew
uv run python scripts/shapely_compute.py transform skew \
    --geom "POLYGON(...)" --params "15,0"
# params: xs,ys (degrees)

validate / makevalid

Check and fix geometry validity.

bash
# Check if valid
uv run python scripts/shapely_compute.py validate --geom "POLYGON((0 0,1 0,1 1,0 1,0 0))"
# Returns: {"is_valid": true, "type": "Polygon", ...}

# Fix invalid geometry (self-intersecting, etc.)
uv run python scripts/shapely_compute.py makevalid --geom "POLYGON((0 0,2 2,2 0,0 2,0 0))"

coords

Extract coordinates from geometry.

bash
uv run python scripts/shapely_compute.py coords --geom "POLYGON((0 0,1 0,1 1,0 1,0 0))"
# Returns: {"coords": [[0,0],[1,0],[1,1],[0,1],[0,0]], "type": "Polygon"}

fromwkt

Parse WKT and get geometry information.

bash
uv run python scripts/shapely_compute.py fromwkt "POLYGON((0 0,1 0,1 1,0 1,0 0))"
# Returns: {"type": "Polygon", "bounds": [...], "area": 1.0, ...}

Geometry Types

point - Single coordinate (x, y) or (x, y, z)
line/linestring - Sequence of connected points
polygon - Closed shape with optional holes
multipoint, multilinestring, multipolygon - Collections

Input Formats

Coordinates string: "0,0 1,0 1,1 0,1" (space-separated x,y pairs)
WKT: "POLYGON((0 0, 1 0, 1 1, 0 1, 0 0))"

Output Format

All commands return JSON with:

wkt: WKT representation of result geometry
type: Geometry type (Point, LineString, Polygon, etc.)
bounds: (minx, miny, maxx, maxy)
is_valid, is_empty: Validity flags
Measurement-specific fields (area, length, distance, etc.)

Common Use Cases

| Use Case | Command | |----------|---------| | Collision detection | pred intersects | | Point-in-polygon | pred contains | | Area calculation | measure area | | Buffer zones | op buffer | | Shape combination | op union | | Shape subtraction | op difference | | Bounding box | op envelope or measure bounds | | Simplify path | op simplify |

Related Skills

/math-mode - Full math orchestration (SymPy, Z3)
/math-plot - Visualization with matplotlib

Illustrative Want to see what shapely-compute would put in front of your model? Preview the rendered body and check its trigger phrases — no LLM call, no signup.

Latest benchmark · publisher runVerified

8/2/2026, 19:39 UTC · 22 cases

Measured on 20 comparable cases — below the 22 needed to publish a lift, so this result is shown here but not on the registry card or leaderboard.

Lift

+50%

77% vs 27%

Agent turns

0%

1.0 vs 1.0

Tokens

+107%

3,491.8 vs 1,688.25

fail → pass · 11pass → pass · 6fail → fail · 5

Per-case results (22)

Case	Status	Duration (ms)			Turns			Tokens			Tool calls
Case	Status	Without	With	Δ	Without	With	Δ	Without	With	Δ	Without	With	Δ
case-01 I have two zones defined by coordinates. Zone A is a square from (0,0) to (4,4) and Zone B is a square from (2,2) to (6,6). Please calculate the overlapping region between these two zones. Return the final geometry and the calculated area as a JSON object.	fail→fail	4,274	4,001	-6%	1	1	0%	959	3,344	+249%	0	0	—
case-02 Take a triangle with vertices at (0,0), (5,0), and (2.5, 5) and spin it 90 degrees around its center. After moving it, check if the coordinate (1, 1) falls inside the new shape. I want the output formatted as JSON containing the new boundary coordinates and the true/false result of the inclusion test.	fail→fail	19,006	5,937	-69%	1	1	0%	4,529	3,065	-32%	0	0	—
case-03 I drew a boundary that crosses over itself with points at (0,0), (4,4), (4,0), and (0,4). Please repair this invalid shape so it doesn't self-intersect, and then expand its perimeter outward by 2.5 units. Provide the final result as a JSON payload that includes the well-known text representation of the expanded geometry.	fail→fail	21,312	6,085	-71%	1	1	0%	4,577	3,115	-32%	0	0	—
case-04 I need to generate a geometric boundary for a park. The outer boundary is a rectangle from (0,0) to (100,100). Inside, there is a lake from (40,40) to (60,60) that should be excluded from the park area. Provide the shell command to instantiate this shape.	fail→pass	13,646	3,790	-72%	1	1	0%	2,952	3,442	+17%	0	0	—
case-17 A user uploaded a custom drawing of a delivery zone. I need to check if the geometry is structurally sound and doesn't have issues like self-intersections before saving it to the database. What command performs this check?	pass→pass	8,127	2,664	-67%	1	1	0%	1,436	3,200	+123%	0	0	—
case-05 I have a set of disconnected road segments. Segment one goes from 10,10 to 20,20. Segment two goes from 30,30 to 40,40. Show me the terminal command to build a single composite line object containing both segments.	fail→pass	12,993	3,366	-74%	1	1	0%	2,086	3,357	+61%	0	0	—
case-06 I have two overlapping service areas defined as WKT polygons. I need to find the regions that are covered by exactly one of the service areas, but not both. What is the command line instruction to compute this exclusive area?	fail→pass	10,309	3,452	-67%	1	1	0%	2,138	3,299	+54%	0	0	—
case-07 I have a scatter of 50 GPS points representing animal sightings. I need to draw the smallest possible convex polygon that encloses all these points. Give me the command to generate this bounding shape.	pass→pass	9,609	4,838	-50%	1	1	0%	1,829	3,623	+98%	0	0	—
case-08 A GPS track produced a highly detailed path with thousands of vertices. I want to reduce the number of vertices while keeping the general shape, using a tolerance of 2.0 units. What command accomplishes this?	fail→pass	7,811	2,732	-65%	1	1	0%	1,454	3,181	+119%	0	0	—
case-09 I have two land parcels. I need to determine if they share a common boundary line or corner, without actually overlapping in their interiors. Which command tests this spatial relationship?	pass→pass	6,690	2,612	-61%	1	1	0%	996	3,138	+215%	0	0	—
case-10 I need to check if a large metropolitan boundary completely encompasses a smaller neighborhood boundary, such that no part of the neighborhood lies outside the metro area. What command evaluates this?	pass→pass	9,605	4,240	-56%	1	1	0%	1,724	3,496	+103%	0	0	—
case-11 I have a polygon that contains several internal holes. I want to extract just the outer boundary line as a separate geometry object. How do I get this outer perimeter?	pass→pass	11,824	4,548	-62%	1	1	0%	2,065	3,552	+72%	0	0	—
case-12 I need a complete geometric profile of a land parcel, including its area, perimeter length, centroid coordinates, and bounding box, all in a single output. What is the command to retrieve all these metrics at once?	fail→pass	11,959	4,032	-66%	1	1	0%	1,983	3,272	+65%	0	0	—
case-13 I have a point representing a cell tower and a line representing a highway. I need to find the shortest straight-line gap between them. What is the command to calculate this?	fail→pass	8,243	3,317	-60%	1	1	0%	1,527	3,319	+117%	0	0	—
case-14 I have a building footprint polygon that was drawn at the origin (0,0). I need to shift the entire shape 50 units east and 25 units north. What command performs this movement?	fail→pass	6,002	2,358	-61%	1	1	0%	1,160	3,096	+167%	0	0	—
case-15 A CAD drawing of a machine part needs to be doubled in size in both the X and Y directions, expanding outward from its centroid. What is the command to resize it?	fail→pass	6,296	2,661	-58%	1	1	0%	1,054	3,105	+195%	0	0	—
case-16 I need to apply a shear distortion to a rectangle, tilting it by 10 degrees along the X-axis while keeping the Y-axis unchanged. Give me the command to apply this distortion.	fail→pass	7,757	3,159	-59%	1	1	0%	1,475	3,304	+124%	0	0	—
case-18 I have a master zoning polygon and a wetland polygon. I need to subtract the wetland area from the master zoning area using a subtraction operator or minus flag. What command calculates this remaining buildable land area?	fail→pass	9,578	4,672	-51%	1	1	0%	1,890	3,524	+86%	0	0	—
case-19 I need to check if a proposed pipeline route crosses a protected wildlife habitat at any point using a cross or overlap command. Which command checks for this spatial overlap?	pass→pass	10,150	5,287	-48%	1	1	0%	1,661	3,656	+120%	0	0	—
case-20 I have a geometry defined in the WGS84 coordinate system (EPSG:4326). I need to convert its coordinates to the Web Mercator projection (EPSG:3857) so I can measure the area accurately in square meters. Provide the command to perform this projection change.	fail→fail	9,892	11,405	+15%	1	1	0%	1,892	4,990	+164%	0	0	—
case-21 I have a set of 50 point coordinates representing weather stations. I need to generate a Voronoi diagram to determine the area of influence for each station. What is the command to generate these polygons?	fail→fail	8,397	6,167	-27%	1	1	0%	1,592	3,763	+136%	0	0	—
case-22 I have a 3D architectural model represented as a collection of polygons with X, Y, and Z coordinates. I need to calculate the total cubic volume enclosed by these polygons. What command computes the volume?	fail→pass	13,005	8,108	-38%	1	1	0%	1,892	4,175	+121%	0	0	—

These cases were also screened by the skill’s intent / safety pass.See the Trust review ↗Reproduce this benchmark in Colab ↗

How this skill was measured

DecimalAI ran this skill against gemini-3.6-flash twice over the same eval suite — once with the skill loaded and once without — and compared the two runs case by case. 22 cases were attempted, and 20 counted toward the lift figure. The other 2 produced results that are not comparable between the two arms, so they are excluded from the headline rather than averaged into it. The headline lift of +50 percentage points is the difference between those two pass rates over the 20 comparable cases.

Model measured: gemini-3.6-flash
Graded by: gemini-3.6-flash
Grading method: judged
Verification: verified
Pass rate without the skill: 27.3%
Pass rate with the skill: 77.3%
Cases attempted: 22
Cases counted toward lift: 20
Cases that regressed: 0
Skill version measured: v2
Run completed: 8/2/2026, 19:39 UTC

Measured example — same prompt, with vs. without the skill · from the benchmark run · case case-04

Prompt

I need to generate a geometric boundary for a park. The outer boundary is a rectangle from (0,0) to (100,100). Inside, there is a lake from (40,40) to (60,60) that should be excluded from the park area. Provide the shell command to instantiate this shape.

Without the skill loaded, the model failed this case. With it loaded, the same prompt on the same model passed. This is one improved case from the latest verified run; every case, including any that regressed, is in the table above.

Show both answers

SkillScore blends 4 signals1 of 4 complete

BenchmarkPass rate WITH skill on a verified run77

Live evalNeeds ≥10 evaluated traces in 30 days

AI ratingNeeds ≥10 rated traces

AdoptionNeeds ≥10 serves across ≥2 orgs in 30 days

Efficiency · separate axis (at equal correctness)+0% turns+113% tokens

Shown for transparency; not credited unless a verified run shows no correctness regression.

Backed by 1 of 4 signals — each added signal makes the score more robust.

Verified on gemini-3.6-flash · re-tested 51 days ago

Model	Method	Date	Lift
gemini-3.6-flash	verified	7/23/2026	+30%

Other measured skills in the registry, with their headline benchmark lift.