ui.Chart.image.seriesByRegion

AI-generated Key Takeaways

• ui.Chart.image.seriesByRegion generates a chart from an image collection, extracting and plotting a specified band's value for each region and image.

• The chart's x-axis represents images labeled by xProperty (default: 'system:time_start'), the y-axis shows the reducer output, and series are regions labeled by seriesProperty (default: 'system:index').

• This function is typically used to generate time series charts.

• It takes an imageCollection, regions, reducer, and optional band, scale, xProperty, and seriesProperty as arguments and returns a ui.Chart.

• An example is provided demonstrating how to chart MODIS NDVI values over time for specified forest and urban regions.

Generates a Chart from an image collection. Extracts and plots the value of the specified band in each region for each image in the collection. Usually a time series.

  - X-axis = Image labeled by xProperty (default: 'system:time_start').

  - Y-axis = Reducer output.

  - Series = Region labeled by seriesProperty (default: 'system:index').

Returns a chart.

Usage	Returns
ui.Chart.image.seriesByRegion(imageCollection, regions, reducer, band, scale, xProperty, seriesProperty)	ui.Chart

Argument	Type	Details
imageCollection	ImageCollection	An ImageCollection with data to be included in the chart.
regions	Feature|FeatureCollection|Geometry|List<Feature>|List<Geometry>	The regions to reduce.
reducer	Reducer	Reducer that generates the value for the y-axis. Must return a single value.
band	Number|String, optional	The band name to reduce using the reducer. Defaults to the first band.
scale	Number, optional	Scale to use with the reducer in meters.
xProperty	String, optional	Property to be used as the label for each image on the x-axis. Defaults to 'system:time_start'.
seriesProperty	String, optional	Property of features in opt_regions to be used for series labels. Defaults to 'system:index'.

Examples

Code Editor (JavaScript)

// Define regions of pixels to reduce and chart a time series for.
var regions = ee.FeatureCollection([
  ee.Feature(
    ee.Geometry.BBox(-121.916, 37.130, -121.844, 37.076), {label: 'Forest'}),
  ee.Feature(
    ee.Geometry.BBox(-122.438, 37.765, -122.396, 37.800), {label: 'Urban'})
]);

// Define an image collection time series to chart, MODIS vegetation indices
// in this case.
var imgCol = ee.ImageCollection('MODIS/006/MOD13A1')
  .filter(ee.Filter.date('2015-01-01', '2020-01-01'))
  .select(['NDVI', 'EVI']);

// Define the chart and print it to the console.
var chart = ui.Chart.image.seriesByRegion({
  imageCollection: imgCol,
  band: 'NDVI',
  regions: regions,
  reducer: ee.Reducer.mean(),
  scale: 500,
  seriesProperty: 'label',
  xProperty: 'system:time_start'
})
.setOptions({
  title: 'Average NDVI Value by Date',
  hAxis: {title: 'Date', titleTextStyle: {italic: false, bold: true}},
  vAxis: {
    title: 'NDVI (x1e4)',
    titleTextStyle: {italic: false, bold: true}
  },
  lineWidth: 5,
  colors: ['0f8755', '808080'],
});
print(chart);