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I'm trying to create a chart of NDVI values that shows the average values for each day of the year for the last 5 years. I think exactly what I need is this: https://developers.google.com/earth-engine/guides/charts_image_collection#uichartimagedoyseriesbyregion

But if I insert a custom feature.collection with two points selected, it only shows one line in the chart, not two. What is the problem?

var pts = ee.FeatureCollection("users/petrjanos/hlavni/random_points");

// Load MODIS vegetation indices data and subset a decade of images.
var vegIndices = ee.ImageCollection('MODIS/006/MOD13A1')
                     .filter(ee.Filter.date('2010-01-01', '2020-01-01'))
                     .select(['NDVI', 'EVI']);

// Define the chart and print it to the console.
var chart = ui.Chart.image
                .doySeriesByRegion({
                  imageCollection: vegIndices,
                  bandName: 'NDVI',
                  regions: pts,
                  regionReducer: ee.Reducer.mean(),
                  scale: 500,
                  //yearReducer: ee.Reducer.mean(),
                  seriesProperty: 'label',
                  startDay: 1,
                  endDay: 365
                })
                .setOptions({
                  title: 'Average NDVI Value by Day of Year',
                  hAxis: {
                    title: 'Day of year',
                    titleTextStyle: {italic: false, bold: true}
                  },
                  vAxis: {
                    title: 'NDVI (x1e4)',
                    titleTextStyle: {italic: false, bold: true}
                  },
                  lineWidth: 5,
                  colors: ['f0af07', '0f8755', '76b349'],
                });
print(chart);

My feature collection: https://code.earthengine.google.com/?asset=users/petrjanos/hlavni/random_points

1 Answer 1

3

The problem is that in the ui.Chart.image.doySeriesByRegion, the seriesProperty argument is set to 'label'. However, that property does not exist in your FeatureCollection. Try changing it to a property that exists in your FeatureCollection such as 'id'.

var chart = ui.Chart.image
                .doySeriesByRegion({
                  imageCollection: vegIndices,
                  bandName: 'NDVI',
                  regions: pts,
                  regionReducer: ee.Reducer.mean(),
                  scale: 500,
                  // Here's the change
                  seriesProperty: 'id',
                  startDay: 1,
                  endDay: 365
                })
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  • Thanks a lot! ..and one more question: if I use Landsat 8 data with filtering (clouds and shadows), can I get continuous lines and not just point like in the picture? imgur.com/C074rOo Commented Jun 29, 2021 at 15:35
  • Hmm its hard to help without a reprex, I would suggest posting another question in SO about this issue. Commented Jun 29, 2021 at 21:24

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