Questions tagged [reducers]
The reducers tag has no usage guidance.
32 questions with no upvoted or accepted answers
2
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Mapping over a reduceRegions command in Earth Engine
I have a feature collection of about 80,000 tiles, and I am trying to calculate the annual maximum drought severity index score for each tile using TerraClimate data. TerraClimate is an image ...
- 405
2
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325
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How to reduce 2 image bands simultaneously using grouped sum region reducer in GEE
I am trying to reduce a region to simultaneously obtain forest loss and forest cover by year from the Hansen dataset. I have tried doing this using a grouped reducer, however, I get the following ...
- 21
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418
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Reduce regions on projected (equal-area) data in Google Earth Engine
I am working with a global raster of soil carbon and a feature collection of ecosystems. I would like to average the carbon in each ecosystem using ReduceRegions in Google Earth Engine, but I need to ...
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2
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1
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Scene boundary issue when reducing sentinel 1 in natural values vs dB
I have written a function that smooths sentinel 1 images by reducing across clusters created from a sentinel 2 median image, and then reduces the sentinel 1 collection to the p5 value. When I run the ...
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Mean Copernicus landcover in multiple polygons with reduceRegions
I would like to estimate the average tree cover for each polygon of a Feature Collection, but the code below only returns empty values. I have tried using different Image Collections (like EVI) and ...
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1
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362
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Google Earth Engine: reduceRegion on multiple bands of daily aggregates
I found this hourly climate-dataset in the GEE catalog, which I want to utilize, to get the daily mean value for six different bands for the time between 2017 and 2022 based on one user-defined AOI (...
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0
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229
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Image reduced by neighborhood in Google Earth Engine appears different in QGIS
I have a classified sentinel 2 image. To remove single pixel outliers I have applied ee.Reducer.neighbourHood() which essentially smoothens the image with a mode reducer. Finally when export the image ...
- 155
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76
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Visualization and vectorizing for AI in Google Earth Engine
I'm glad to find this space, I come from a background in economics and do not know the first thing about GIS (hope to learn as I go with this project).
I found an interesting dataset (https://...
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219
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How to calculate sum of night light radiance for each feature in a feature collection?
I have a shapefile which contains 36 polygons (districts/counties). For each district, I want to calculate sum of lights (as well as count total number of pixels). I tried following code but failed. ...
- 105
1
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541
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ERA5-Land Hourly Precipitation Chart and Map
I am little bit confused how to handle the "ERA5-Land Hourly"-Dataset in GEE. I want the total precipitation of every month from 2018 till end of 2021 for my area.
For the chart I took the ...
- 153
1
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1
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96
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How to reduce an image resulting from an expression?
In the code below I use the ee.Image.expression method to combine two images into one. I am then able to display the resulting image using geemap, and the image looks as expected. However when using ...
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244
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Can you create a custom reducer?
For a specific size of area (e.g. 1km squared), I want to apply formulas to a feature collection.
These formulas aren't included in the reducers available. For example, I want to get the circular mean ...
- 61
1
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1k
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GEE: Is ee.Reducer.mean() can ignore NULL values?
I'm trying to create a time-series of NDVI for 6 sub-regions.
I've downloaded the relevant Sentinel-2 images, and filtered the region containing these 6 sub-regions, filtered the time-period and ...
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1
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95
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How to determine mean VIIRS Nighttime Day/Night Band Composites Version 1 for each district (county)?
How to determine mean VIIRS Nighttime Lights for each district (county) shapefile attached ?
The exported csv file does not contain required results!
var start = ee.Date('2017-01-01');
var end = ee....
- 105
1
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0
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224
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Compute neighborhood statistics in GEE with your own function/reducer
I have generated an Image in GEE, which corresponds to a classification. Each pixel is assigned to 1 group (out of a certain number of groups, let’s say 100). I would like, for each pixel, to compute ...
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1
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84
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Why does means not appear in the Feature Collections after applying a ee.Reducer.mean() through the image.reduceRegions
I am trying to aggregate the MODIS ET data into 1km by 1km grid squares. I have tried applying the ee.Reducer.means through the image.reduceRegions to get the mean value of MODIS-ET pixels within the ...
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Is there a size limit to reduceRegion in Google Earth Engine?
I want to use some points (point_695 in this case) to extract their values in a time series trajectory of Landsat 8 image scenes from 2014-01-01 to 2014-05-15. When I use reduceRegions() to do the ...
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0
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1
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114
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How to extract the mean value of a band in each image in a image collection in Google Earth Engine
I am trying to extract the mean value of a band in all of the images of a image collection so I can then plot the values in a box plot to find outliers etc.
So far I have created a function that ...
- 51
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2
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139
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reduceRegion works but reduceRegions returns null values for all reducer
When using ee.reduceRegions() I try to estimate the mean values of copernicus landcover values within all features in a feature collection I get 'null' as a result for all reducers I have tried (mean,...
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53
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Google Earth Engine: User memory limit exceeded error when try to reduce and build a multiband imagecollection
I have a long imagecollection of Landsat-5 images from 1984 to 2011.
This imagecollection was cropped in a smaller ROI, bit flags and scaling factors applied and for each image two new bands were ...
- 483
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0
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89
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Selecting a subset of features from feature collection in reduceRegions()
In an attempt to find ndvi and gndvi over a geometry containing 160 polygons, I have the following code.
var s2 = ee.ImageCollection('COPERNICUS/S2_HARMONIZED');
var geometry = ee.FeatureCollection('...
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0
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1
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29
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Error exporting the mean of an Image List (of 173 Elements)
I am trying to export the LST mean for a period of time. I converted the Image collection I had to a List, but I cannot calculate the mean of all the elements within the List so there is only 1 image ...
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1
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459
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Exporting values from Images in ImageCollection to CSV
I am working with rainfall monthly totals for a 30-year period using CHIRPS pentad.
//1.Reference Period
var historical = ee.List.sequence(1991, 2020)
var months = ee.List.sequence(1, 5)
//print(...
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1
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253
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Using ee.Reducer on monthly time series with missing data
I am trying to generate a value of mean MODIS LST for each month in a time series for a feature collection, as well as an overall timeseries minimum and maximum LST for each month of the year. When I ...
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327
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Convert GEE object to image?
I have tried to calculate the average precipitation in each cropland. However, it seems I have a problem generating a map of the final result. It does show that "Expression does not evaluate to ...
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76
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I need to print RMSE but don't know why error is coming
I need to print root mean squared error (RMSE) but don't know why error is coming. Can any one share code how I can calculate RMSE?
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1
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63
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Function to find annual maximum outcome for twelve years of monthly image bands in Earth Engine
I have a feature collection of about 80,000 tiles, and I am trying to calculate the annual maximum drought severity index score for each tile using TerraClimate data. TerraClimate is an image ...
- 405
0
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0
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148
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Counting number of pixels in each tile in Earth Engine
I have 0.02° tiles across some regions of interest in Africa. I am trying to find the percent of 300m ESA land cover pixels that are classified as cropland (classification 10-30) for each tile, as ...
- 405
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1
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351
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Google Earth Engine: get data ready for ML export
I need to export data from GEE to get processed in MATLAB. I want to export CSV files of a region, aggregating meteo data ( CAMS, ERA5, MODIS AOT) with sentinel-2 images. These images have already ...
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416
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Google Earth Engine: Sum property values for region
I have run the code below, to find regions where data is available from my image collection, which This produces a feature collection per region and per variable (in this case SST and Salinity).
// ...
- 517
0
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1
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437
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Exporting table of daily temperature (ERROR: Internal Error)
I am trying to download a table of daily temperature for the year of 2001 and all Brazilian municipalities in Google Earth Engine Code (GEE). After mapping a Reduce Regions function and flatten to ...
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-1
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1
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EEException: User memory limit exceeded using GEE with specific dataset
I'm working with the Google Earth Engine API and the dataset SPL4SMGP.007 SMAP L4 Global 3-hourly 9-km Surface and Root Zone Soil Moisture. I'm trying to get the minimum and maximum value for the band ...
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