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ee.Geometry.Point.length
使用集合让一切井井有条
根据您的偏好保存内容并对其进行分类。
返回几何图形的线性部分的长度。多边形部分会被忽略。多几何图形的长度是其组成部分的长度之和。
用法 | 返回 |
---|
Point.length(maxError, proj) | 浮点数 |
参数 | 类型 | 详细信息 |
---|
此:geometry | 几何图形 | 输入几何图形。 |
maxError | ErrorMargin,默认值:null | 执行任何必要的重新投影时可容忍的最大误差量。 |
proj | 投影,默认值:null | 如果指定,结果将采用相应投影的坐标系的单位。否则将以米为单位。 |
示例
代码编辑器 (JavaScript)
// Define a Point object.
var point = ee.Geometry.Point(-122.082, 37.42);
// Apply the length method to the Point object.
var pointLength = point.length();
// Print the result to the console.
print('point.length(...) =', pointLength);
// Display relevant geometries on the map.
Map.setCenter(-122.085, 37.422, 15);
Map.addLayer(point,
{'color': 'black'},
'Geometry [black]: point');
Python 设置
如需了解 Python API 和如何使用 geemap
进行交互式开发,请参阅
Python 环境页面。
import ee
import geemap.core as geemap
Colab (Python)
# Define a Point object.
point = ee.Geometry.Point(-122.082, 37.42)
# Apply the length method to the Point object.
point_length = point.length()
# Print the result.
display('point.length(...) =', point_length)
# Display relevant geometries on the map.
m = geemap.Map()
m.set_center(-122.085, 37.422, 15)
m.add_layer(point, {'color': 'black'}, 'Geometry [black]: point')
m
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最后更新时间 (UTC):2025-07-26。
[null,null,["最后更新时间 (UTC):2025-07-26。"],[[["\u003cp\u003eCalculates the length of linear geometry parts, ignoring polygonal areas and summing lengths for multi-geometries.\u003c/p\u003e\n"],["\u003cp\u003eReturns the length in meters by default or in the units of a specified projection if provided.\u003c/p\u003e\n"],["\u003cp\u003eAccepts an optional \u003ccode\u003emaxError\u003c/code\u003e parameter to control reprojection accuracy.\u003c/p\u003e\n"],["\u003cp\u003eThis method is applicable to \u003ccode\u003ePoint\u003c/code\u003e geometry objects, but will return 0 as it lacks linear parts.\u003c/p\u003e\n"]]],["The `length()` method calculates the length of linear parts within a geometry, ignoring polygonal sections. For multi-geometries, it sums the lengths of individual components. The method accepts `maxError` to define reprojection tolerance and `proj` to specify output units (defaults to meters). Applying it to a point will return a float. Example codes are provided in both JavaScript and Python to define a point object, calculate its length, and display it on a map.\n"],null,["# ee.Geometry.Point.length\n\nReturns the length of the linear parts of the geometry. Polygonal parts are ignored. The length of multi geometries is the sum of the lengths of their components.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|-----------------------------------------|---------|\n| Point.length`(`*maxError* `, `*proj*`)` | Float |\n\n| Argument | Type | Details |\n|------------------|----------------------------|----------------------------------------------------------------------------------------------------------------------------|\n| this: `geometry` | Geometry | The input geometry. |\n| `maxError` | ErrorMargin, default: null | The maximum amount of error tolerated when performing any necessary reprojection. |\n| `proj` | Projection, default: null | If specified, the result will be in the units of the coordinate system of this projection. Otherwise it will be in meters. |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\n// Define a Point object.\nvar point = ee.Geometry.Point(-122.082, 37.42);\n\n// Apply the length method to the Point object.\nvar pointLength = point.length();\n\n// Print the result to the console.\nprint('point.length(...) =', pointLength);\n\n// Display relevant geometries on the map.\nMap.setCenter(-122.085, 37.422, 15);\nMap.addLayer(point,\n {'color': 'black'},\n 'Geometry [black]: point');\n```\nPython setup\n\nSee the [Python Environment](/earth-engine/guides/python_install) page for information on the Python API and using\n`geemap` for interactive development. \n\n```python\nimport ee\nimport geemap.core as geemap\n```\n\n### Colab (Python)\n\n```python\n# Define a Point object.\npoint = ee.Geometry.Point(-122.082, 37.42)\n\n# Apply the length method to the Point object.\npoint_length = point.length()\n\n# Print the result.\ndisplay('point.length(...) =', point_length)\n\n# Display relevant geometries on the map.\nm = geemap.Map()\nm.set_center(-122.085, 37.422, 15)\nm.add_layer(point, {'color': 'black'}, 'Geometry [black]: point')\nm\n```"]]