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Merges all geometries in a given collection into one and returns a collection containing a single feature with only an ID of 'union_result' and a geometry.
Usage
Returns
FeatureCollection.union(maxError)
FeatureCollection
Argument
Type
Details
this:collection
FeatureCollection
The collection being merged.
maxError
ErrorMargin, default: null
The maximum error allowed when performing any necessary reprojections. If not specified, defaults to the error margin requested from the output.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2023-10-06 UTC."],[[["\u003cp\u003e\u003ccode\u003eunion()\u003c/code\u003e merges all geometries within a FeatureCollection into a single geometry, returning a new FeatureCollection containing one feature with an ID of 'union_result'.\u003c/p\u003e\n"],["\u003cp\u003eThe resulting FeatureCollection from \u003ccode\u003eunion()\u003c/code\u003e will only have the merged geometry and an ID, discarding any original properties from the input features.\u003c/p\u003e\n"],["\u003cp\u003eAn optional \u003ccode\u003emaxError\u003c/code\u003e argument can be used to specify the maximum allowed error for reprojection during the merge process.\u003c/p\u003e\n"]]],[],null,["# ee.FeatureCollection.union\n\nMerges all geometries in a given collection into one and returns a collection containing a single feature with only an ID of 'union_result' and a geometry.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|-----------------------------------------|-------------------|\n| FeatureCollection.union`(`*maxError*`)` | FeatureCollection |\n\n| Argument | Type | Details |\n|--------------------|----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------|\n| this: `collection` | FeatureCollection | The collection being merged. |\n| `maxError` | ErrorMargin, default: null | The maximum error allowed when performing any necessary reprojections. If not specified, defaults to the error margin requested from the output. |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\n// FeatureCollection of power plants in Belgium.\nvar fc = ee.FeatureCollection('WRI/GPPD/power_plants')\n .filter('country_lg == \"Belgium\"');\n\nprint('Original FeatureCollection', fc);\n\n// Merge all geometries into one. A FeatureCollection with a single feature\n// with no properties is returned.\nprint('All geometries merged into one', fc.union(1));\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# FeatureCollection of power plants in Belgium.\nfc = ee.FeatureCollection('WRI/GPPD/power_plants').filter(\n 'country_lg == \"Belgium\"')\n\nprint('Original FeatureCollection:', fc.getInfo())\n\n# Merge all geometries into one. A FeatureCollection with a single feature\n# with no properties is returned.\nprint('All geometries merged into one:', fc.union(1).getInfo())\n```"]]
