GEE之FeatureCollection入门操作1

FeatureCollection

GEE之FeatureCollection入门操作1

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FeatureCollection 区域选择，点选。

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FilterMetadata

官方函数：

Shortcuts to filter a collection by metadata. This is equivalent to this.filter(ee.Filter.metadata(...)).

Returns the filtered collection.

Arguments:
this:collection (Collection):
The Collection instance.

name (String):
The name of a property to filter.

operator (String):
The name of a comparison operator. Possible values are: "equals", "less_than", "greater_than",
"not_equals", "not_less_than", "not_greater_than", "starts_with",
"ends_with", "not_starts_with", "not_ends_with", "contains",
"not_contains".

value (Object):
- The value to compare against.

Returns: Collection

用法

输入参数有3个，第一个是选择的属性名字，第二个是判断符号（等于，小于等），第三个是目标值。 比如

filterMetadata('flag','equals','false')
//option
"equals", "less_than", "greater_than","not_equals", "not_less_than", "not_greater_than", 
"starts_with","ends_with", "not_starts_with", "not_ends_with", "contains","not_contains".

就是选择 flag等于false的feature

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如果点集FeatureCollection ，还可以用filterBounds() 去选择区域；跟ImageCollection 同理。

如果有一个点集和矢量集合，而直接在GEE中运行会内存不足，则可以通过filterMetadata选择矢量集合中单个feature，从而可以进行循环；然后求geometry属性，选择Bounds区域 ，从点集合中选择出对应feature中的点集。

var eft = table.filterMetadata('flag','equals',4);
var roi = eft.geometry();
var cepo = table2.filterBounds(roi);

这样就可以大区域变小区域，进行循环，提取数值等。