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How to get statistics in each zone of an image?
You can get statistics in each zone of an Image or FeatureCollection by using reducer.group () to group the output of a reducer by the value of a specified input. For example, to compute the total population and number of housing units in each state, this example groups the output of a reduction of a census block FeatureCollection as follows:
Which is an example of a zonal statistic?
This type of computation is sometimes called “zonal statistics” where the zones are specified as the grouping band and the statistic is determined by the reducer. In the following example, change in nightlights in the United States is grouped by land cover category:
How to Group a reduction in Google Earth?
For example, to compute the total population and number of housing units in each state, this example groups the output of a reduction of a census block FeatureCollection as follows: // Load a collection of US census blocks. // Compute sums of the specified properties, grouped by state code. // Print the resultant Dictionary.
How is the groupfield argument used in Google Earth?
// Compute sums of the specified properties, grouped by state code. // Print the resultant Dictionary. The groupField argument is the index of the input in the selectors array that contains the codes by which to group, the groupName argument specifies the name of the property to store the value of the grouping variable.
How to calculate region in Google Earth Engine?
// Load input imagery: Landsat 7 5-year composite. // Load an input region: Sierra Nevada. // Reduce the region. The region parameter is the Feature geometry. // The result is a Dictionary. Print it. To force the computation, it suffices to print the result, which the Code Editor will display as a Dictionary in the console.
How is the scale determined in Earth Engine?
In general, specifying the scale is sufficient and results in more readable code. Earth Engine determines which pixels to input to the reducer by first rasterizing the region. If a scale is specified without a CRS, the region is rasterized in the image’s native projection scaled to the specified resolution.
How to set scale in Google Earth Engine?
See this page for more information about how Earth Engine handles scale. There are two ways to set the scale: by specifying the scale parameter, or by specifying a CRS and CRS transform. (See the glossary for more information about CRS’s and CRS transforms). For example, the meanDictionary reduction (above) is equivalent to the following: