很多时候我们会在已经公开的土地分类影像中按照矢量集合中的元素进行逐个矢量的面积提取，这里主要的问题是我们如何进行遍历每一个矢量，而这里有两个关键函数就显得非常重要，一个是遍历每一个矢量求出每一个矢量的范围，另外就是将其求出的面积放入到指定的集合中，并以字典的形式返回，这样就可以求出矢量集合中的每一个矢量范围内的土地分类面积。
数据：
GlobCover 2009 is a global land cover map based on ENVISAT's Medium Resolution Imaging Spectrometer (MERIS) Level 1B data acquired in full resolution mode with a spatial resolution of approximately 300 meters.
resolution
300 meters
Bands Table
| Name | Description |
|---|---|
| landcover | The land cover map is derived by an automatic and regionally-tuned classification of a time series of global MERIS FR mosaics for the year 2009. The global land cover map counts 22 land cover classes defined with the United Nations (UN) Land Cover Classification System (LCCS). |
| qa | Binary quality band indicating whether the reference dataset has been used inste |