Turf Skills

**ALWAYS use this skill immediately** when the user mentions any spatial analysis, geospatial operations, coordinate calculations, or GeoJSON processing task...

Security Scan

The skill's code, docs, and runtime instructions are consistent: it is a Node.js CLI wrapper around Turf.js for geospatial operations and does not request unrelated credentials or external endpoints.

Purpose & Capability

Name/description (Turf spatial operations) matches the bundled code and package-lock which depend on @turf/* modules. Required capabilities (file input, many turf actions) are appropriate for the stated purpose. Minor doc wording is aggressive ('ALWAYS use this skill immediately') but that is a policy recommendation in SKILL.md rather than a mismatch with required permissions.

Instruction Scope

SKILL.md instructs use for GeoJSON/coordinate tasks and shows CLI invocation patterns. The runtime code only reads inputs provided via --input/--file/--input2/--file2 and writes output to --output or stdout. There are no instructions to read other system state, environment variables, or transmit data to third-party endpoints.

Install Mechanism

Registry shows no install spec (instruction-only), but the package includes Node.js CLI code and a standard package-lock.json referencing npm registry tarballs for Turf packages — no custom downloads, obscure URLs, or archive extracts. The skill requires Node.js runtime (compatibility Node >=16) which is expected.

Credentials

The skill declares no required environment variables, credentials, or config paths. The codebase likewise does not access process.env for secrets. No disproportionate credential access is requested.

Persistence & Privilege

The skill is not marked always:true. Autonomous invocation is allowed by default (disable-model-invocation:false), which is normal for skills. SKILL.md's 'always use' language could lead an agent to prefer this skill for geography tasks; combine that with autonomous invocation if you want to control automatic use.

Assessment

This skill appears to be a straightforward Turf.js CLI wrapper and is internally coherent. Before installing: (1) verify the package source (homepage is missing in metadata and owner is unknown) or prefer the official npm/turf ecosystem; (2) audit package.json/package-lock and run npm audit locally; (3) be careful when passing --file or --file2: the tool will read any filesystem path you provide, so do not point it at sensitive files (credentials, private configs); (4) if you don't want the agent to call it automatically whenever geography terms appear, consider disabling autonomous invocation or restricting skill usage policies; (5) note small metadata mismatches (package-lock shows 1.0.1 while SKILL.md/version is 1.0.2) — you may want to confirm the intended release/version from the author.

Turf.js spatial analysis skill for Claude Code.

Usage

turf-skills --action <name> [options]

Actions

Measurement 测量

Action	Description	Required	Optional
distance	Distance between two points 两点距离	input, input2	units
area	Area of polygon 多边形面积(m²)	input
length	Length of line 线长度	input	units
bearing	Bearing between points 方位角	input, input2
destination	Point at distance+bearing 目标点	input	distance, direction, units
midpoint	Midpoint of two points 中点	input, input2
center	Center of features 中心点	input
centroid	Centroid 质心	input
centerOfMass	Center of mass 重心	input
along	Point along line 沿线取点	input	distance, units
bbox	Bounding box 边界框	input
bboxPolygon	Bbox as polygon 边界框多边形	input or bbox
envelope	Envelope 包络矩形	input

Query 空间查询

Action	Description	Required	Optional
booleanPointInPolygon	Point in polygon 点在多边形内	input(point), input2(polygon)
booleanContains	Feature contains another 包含	input, input2
booleanCrosses	Features cross 交叉	input, input2
booleanDisjoint	Features disjoint 不相交	input, input2
booleanEqual	Features equal 相等	input, input2
booleanIntersects	Features intersect 相交	input, input2
booleanOverlap	Features overlap 重叠	input, input2
booleanWithin	Feature within another 在内部	input, input2
booleanParallel	Lines parallel 平行	input, input2
booleanPointOnLine	Point on line 点在线上	input(point), input2(line)
nearestPoint	Nearest point in collection 最近点	input(point), input2(FC)

Transformation 变换

Action	Description	Required	Optional
buffer	Buffer zone 缓冲区	input	radius, units
union	Union polygons 合并	input, input2
intersect	Intersect polygons 求交	input, input2
difference	Difference polygons 求差	input, input2
simplify	Simplify geometry 简化	input	tolerance
convex	Convex hull 凸包	input
concave	Concave hull 凹包	input	maxEdge, units
dissolve	Dissolve polygons 融合	input(FC)	propertyName
voronoi	Voronoi diagram 泰森多边形	input(points)	bbox
tin	TIN 不规则三角网	input(points)	propertyName
bezierSpline	Bezier spline 贝塞尔曲线	input(line)	resolution, sharpness
transformRotate	Rotate 旋转	input	angle
transformScale	Scale 缩放	input	factor
transformTranslate	Translate 平移	input	distance, direction, units

Helpers 创建

Action	Description	Required	Optional
point	Create point 创建点	coordinates	properties
lineString	Create line 创建线	coordinates	properties
polygon	Create polygon 创建面	coordinates	properties
multiPoint	Create MultiPoint	coordinates	properties
multiLineString	Create MultiLineString	coordinates	properties
multiPolygon	Create MultiPolygon	coordinates	properties
randomPoint	Random points 随机点		count, bbox
randomLineString	Random lines 随机线		count, bbox
randomPolygon	Random polygons 随机面		count, bbox

Interpolation 插值/网格

Action	Description	Required	Optional
interpolate	IDW interpolation 反距离加权插值	input(points)	cellSide, gridType, propertyName, units
isobands	Isobands 等值面	input(points)	breaks, propertyName
isolines	Isolines 等值线	input(points)	breaks, propertyName
hexGrid	Hex grid 六边形网格	bbox, cellSide	units
pointGrid	Point grid 点网格	bbox, cellSide	units
squareGrid	Square grid 方形网格	bbox, cellSide	units
triangleGrid	Triangle grid 三角网格	bbox, cellSide	units

Clustering 聚类

Action	Description	Required	Optional
clustersKmeans	K-means clustering K均值聚类	input(points FC)	numberOfClusters
clustersDbscan	DBSCAN clustering 密度聚类	input(points FC)	maxDistance, units, minPoints

Examples

Calculate distance 计算距离

turf-skills --action distance \
  --input '{"type":"Point","coordinates":[120,30]}' \
  --input2 '{"type":"Point","coordinates":[121,31]}' \
  --units kilometers

Point in polygon 点在多边形内

turf-skills --action booleanPointInPolygon \
  --input '{"type":"Point","coordinates":[120.5,30.5]}' \
  --input2 '{"type":"Polygon","coordinates":[[[120,30],[121,30],[121,31],[120,31],[120,30]]]}'

Buffer 缓冲区

turf-skills --action buffer \
  --input '{"type":"Point","coordinates":[120,30]}' \
  --radius 5 --units kilometers

Read from file 从文件读取

turf-skills --action area --file polygon.geojson
turf-skills --action booleanContains --file polygon.geojson --file2 point.geojson

Output to file 输出到文件

turf-skills --action buffer --file point.geojson --radius 10 --output result.geojson

Create geometry 创建几何

turf-skills --action point --coordinates '[120,30]' --properties '{"name":"test"}'
turf-skills --action randomPoint --count 100 --bbox '[120,30,121,31]'

Grid generation 网格生成

turf-skills --action hexGrid --bbox '[120,30,121,31]' --cellSide 5 --units kilometers

Clustering 聚类分析

turf-skills --action clustersKmeans --file points.geojson --numberOfClusters 5
turf-skills --action clustersDbscan --file points.geojson --maxDistance 1 --minPoints 3

Natural Language Patterns

Common Queries 常见查询

Query Pattern	Action	Example
"distance between [coordinates]"	distance	"Calculate distance between [120,30] and [121,31]"
"area of [polygon]"	area	"Find area of this polygon"
"length of [line]"	length	"Calculate length of this line in km"
"is [point] inside [polygon]"	booleanPointInPolygon	"Is this point inside the polygon?"
"buffer [radius] km/mi around [point]"	buffer	"Create a 5km buffer around this point"
"convex hull of [points]"	convex	"Compute convex hull of these points"
"cluster points into [n] groups"	clustersKmeans	"Cluster these points into 5 groups"
"nearest point to [location]"	nearestPoint	"Find nearest point to [120,30]"
"simplify geometry"	simplify	"Simplify this geometry"
"union/intersect/difference"	union/intersect/difference	"Union these two polygons"
"generate hex/square/triangle grid"	hexGrid/squareGrid/triangleGrid	"Generate hex grid for this area"
"rotate/scale/translate"	transformRotate/transformScale/transformTranslate	"Rotate this polygon by 45 degrees"

Chinese Query Patterns 中文查询模式

查询模式	操作	示例
"计算...的距离"	distance	"计算北京和上海的距离"
"计算...的面积"	area	"计算这个多边形的面积"
"点是否在多边形内"	booleanPointInPolygon	"天安门是否在五环内？"
"创建...缓冲区"	buffer	"创建5公里缓冲区"
"计算凸包"	convex	"计算这些点的凸包"
"聚类分析"	clustersKmeans/clustersDbscan	"对这些点进行聚类"
"查找最近点"	nearestPoint	"查找距离[120,30]最近的点"
"生成网格"	hexGrid/squareGrid	"生成六边形网格"
"旋转/缩放/平移"	transformRotate/transformScale/transformTranslate	"旋转多边形45度"

Real-World Scenarios 实际场景

# Beijing to Shanghai distance
turf-skills --action distance \
  --input '{"type":"Point","coordinates":[116.397428,39.90923]}' \
  --input2 '{"type":"Point","coordinates":[121.473701,31.230416]}' \
  --units kilometers

# 5km buffer around a location
turf-skills --action buffer \
  --input '{"type":"Point","coordinates":[116.397428,39.90923]}' \
  --radius 5 --units kilometers

# Point in polygon check
turf-skills --action booleanPointInPolygon \
  --input '{"type":"Point","coordinates":[116.397428,39.90923]}' \
  --input2 '{"type":"Polygon","coordinates":[[[116.1,39.7],[116.8,39.7],[116.8,40.1],[116.1,40.1],[116.1,39.7]]]}'

# Generate hex grid for a region
turf-skills --action hexGrid --bbox '[116,39,117,40]' --cellSide 10 --units kilometers

# K-means clustering
turf-skills --action clustersKmeans --file points.geojson --numberOfClusters 3

When to Use This Skill 何时使用此技能

ALWAYS Use For 务必使用：

• Complex operations: buffer, grid generation, clustering, interpolation
• GeoJSON output required: when the result needs to be valid GeoJSON
• Multiple operations: chaining spatial analyses
• File I/O: reading/writing GeoJSON files

Consider Direct Turf.js For 考虑直接使用：

• Simple one-off calculations: distance, area, bearing (if already in a Node.js script)
• Performance-critical loops: when calling the same operation thousands of times

Performance Notes 性能说明：

• Skill CLI has startup overhead (~1-2 seconds)
• For complex operations, skill is faster and more efficient
• Skill ensures consistent Turf.js implementation

Best Practices 最佳实践

1. Input Validation 输入验证

Always validate coordinates before processing:

• Longitude: -180 to 180
• Latitude: -90 to 90
• Ensure polygons are closed (first == last coordinate)

2. Units 单位

• Default unit: kilometers (千米)
• Options: kilometers, miles, meters, degrees, radians
• Always specify units explicitly for clarity

3. File Handling 文件处理

• Use --file for reading GeoJSON files
• Use --output to save results
• Supports both .geojson and .json extensions

4. Error Handling 错误处理

• Check that required parameters are provided
• Validate GeoJSON format before passing to actions
• Handle empty results gracefully

Real-World Use Cases 实际应用场景

1. Delivery Zone Planning 配送范围规划

# Create 5km delivery zones around stores
turf-skills --action buffer \
  --file stores.geojson \
  --radius 5 \
  --units kilometers \
  --output delivery-zones.geojson

2. Geographic Fence Check 地理围栏检测

# Check if customer address is within service area
turf-skills --action booleanPointInPolygon \
  --input '{"type":"Point","coordinates":[lng,lat]}' \
  --file service-area.geojson

3. Store Location Clustering 门店位置聚类

# Cluster customer locations for optimal store placement
turf-skills --action clustersKmeans \
  --file customers.geojson \
  --numberOfClusters 5 \
  --output clusters.geojson

4. Heat Map Grid 热力图网格

# Generate hex grid for population density visualization
turf-skills --action hexGrid \
  --bbox '[116,39,117,40]' \
  --cellSide 1 \
  --units kilometers \
  --output grid.geojson

5. Route Simplification 路线简化

# Simplify GPS track for storage efficiency
turf-skills --action simplify \
  --file gps-track.geojson \
  --tolerance 0.0001 \
  --output simplified-track.geojson

Input/Output Formats 输入输出格式

GeoJSON Feature Structure

{
  "type": "Feature",
  "properties": {
    "name": "Beijing",
    "population": 21540000
  },
  "geometry": {
    "type": "Point",
    "coordinates": [116.397428, 39.90923]
  }
}

Supported Geometry Types

• Point - 点
• LineString - 线
• Polygon - 面
• MultiPoint - 多点
• MultiLineString - 多线
• MultiPolygon - 多面
• FeatureCollection - 要素集合

Troubleshooting 故障排除

Common Issues 常见问题

Issue: "Error: Unknown action"

• Solution: Use --list to see available actions

Issue: "Error: Cannot read property"

• Solution: Check GeoJSON format, ensure proper nesting

Issue: Empty result for intersection/union

• Solution: Geometries may not overlap; check coordinates

Issue: Distance calculation seems wrong

• Solution: Verify units parameter (default is kilometers)

Additional Resources 更多资源

• Turf.js Documentation: https://turfjs.org/
• GeoJSON Specification: https://geojson.org/
• Coordinate Reference Systems: https://epsg.io/