Questions tagged [reducers]

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33 views

Calculating R-Squared Using the 'Residuals' Band from Google Earth Engine's linearRegression() Reducer

I am trying to calculate an R-Squared for a harmonic linear regression I did with two dependent variables across an image collection, using the linearRegression reducer on Google Earth Engine. The ...
1
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1answer
28 views

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 ...
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1answer
23 views

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 ...
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1answer
19 views

Google Earth Engine fails to export variable

I am exporting zonal statistics for 0.01-degree tiles in various locations in Africa. When I try to find the tile's 2010 percent forest cover from the GFCC data, I use a reducer function: var ...
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1answer
87 views

How to run BFAST Monitor over a FeatureCollection in GEE

I am working with BFAST Monitor in Google Earth Engine, and I would like to run the algorithm over a FeatureCollection containing individual points of interest. Like this: var norway = ee....
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0answers
21 views

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 ...
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0answers
32 views

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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0answers
24 views

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 ...
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0answers
49 views

Google Earth Engine large reduce resolution and reproject fails to export to drive

I'm attempting to aggregate (reduceResolution) a higher resolution image (e.g. 30m global forest loss as in code below) to a lower resolution image (e.g. 1000m pixels), based on some criteria, with a ...
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0answers
45 views

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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2answers
46 views

Google Earth Engine memory capacity exceeded

I am trying to export to a csv table with total precipitation per month-year per polygon (~5571 polygons) from 2001-2019 (228 time steps). I am using the CHIRPS dataset (daily data) so had to reduce ...
1
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1answer
28 views

Count number of pixels within polygon that have a particular range of values in Earth Engine

I am working with the Global Forest Cover Change (GFCC) rasters for 2000 to create a forest quality score for 0.01 degree tiles (the percent of the tile with +50% forest cover, divided by the percent ...
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0answers
36 views

Getting maximum value of a cumulativeCost Image in Earth Engine

I'm trying to get the max value of a generated cumulativeCost Image in Earth Engine, via the Python API. I thought reduceRegion should work, but it dies. My relevant code: malawi = ee....
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1answer
36 views

Earth Engine: different results with “covariance” and “centeredCovariance” on de-meaned data?

I am trying to compute a covariance matrix in earth engine. EE offers two reducers: ee.Reducer.centeredCovariance ee.Reducer.covariance. My understanding is that ee.Reducer.covariance on the raw ...
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0answers
44 views

GEE Python API Resample Image Collection from 3 hr to 1 day temporal resolution

Is there a way to resample an image collection to a different temporal resolution in GEE? I am extracting points from several bands in the GLDAS asset, which has a 3hr temporal resolution. I have a ...
1
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1answer
38 views

Error when trying to add system:time_start when using reduceRegions in Google Earth Engine

I am reducing an image collection into a feature collection by using a function to map the reduceRegions function to each image in a collection. I'm trying to make sure the system:time_start property ...
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1answer
28 views

GEE Process for deciding what pixels lie within a geometry

I am using image and collection reducers to extract mean values of several assets (for example, prism precipitation and pml2 ET) from within USGS watershed boundaries which I load in as geometries. I ...
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1answer
66 views

Temporally reducing image bands using Google Earth Engine

I am trying to temporally reduce an image from 365 bands (daily) to 12 bands (monthly). Context: I imported an image collection with Soil Moisture (SM) that had 8 values per day (every three hours). I ...
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1answer
87 views

Calculating zonal statistics for each polygon in shapefile using GEE

I have shapefile of counties and want to calculate mean NDVI for each. I know reducing connected components and ee.reducer.mean can be helpful in GEE but it wants it as CSV for further analysis in R ...
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0answers
62 views

Exporting district level precipitation data for series of months using Google Earth Engine Python API

I am trying to export precipitation data for a range of months at the district level of Somalia using GEE's phython api. I'm using the following code #import Somalia district shape file and convert to ...
2
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1answer
23 views

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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1answer
73 views

How to find top 10 greatest values in a GEE image collection?

I'm trying to categorize temperature extremes for a region. Using the Hycom GEE dataset, I know that using a Reducer I can find the maximum value for each pixel across the image collection (see code ...
2
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1answer
265 views

Count pixels inside a polygon with Google Earth Engine

i'm pretty new on GEE, so i hope someone can help me with this. As the title say, i'm looking for a way to calculate how many pixels i have inside a polygon. I tried to do it with reduceRegion and ee....
2
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1answer
37 views

Reduction over an image collection Google Earth Engine

I am using CHIRPS data set (daily precipitation) to derive mean, median, min and max precipitation within a certain time frame. Then, I want to extract the values at specific locations included in a ...
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1answer
94 views

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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0answers
38 views

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 ...
4
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1answer
62 views

Retrieve projection inside .map() GEE

When using a reducing function such as .reduceRegion(), a provided projection is necessary. This projection has to be provided as CRS String, and crsTransform List. Both are optainable with : var ...
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1answer
97 views

How to calculate the area of classified pixels in Google Earth Engine?

I'm using the Python API of GEE in a Jupyter notebook. I'd like to perform a surface evaluation of classified pixels. I have a ee_map with one band called gfc that have values in [1,2 ... 19, 30, 40, ...
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1answer
35 views

Transform an ecozone raster to vector

I want to transform a ee.Iamge that descripbe the ecozone of a specific country to a vector. I try to reproduce this example but I cannot get anything else than black vector... //load the country ...
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1answer
107 views

Extracting NDVI for Landcover Classes in Google Earth Engine

I am working on a project where I have created a supervised classification of an image which contains four land cover classes. I have reduced the classification to a frequency histogram that displays ...
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0answers
24 views

Google Earth Engine: Different calculations per region in feature collection

I have a mean SST value, which I have reduced per pergion. var sstCollection = ee.ImageCollection('NASA/OCEANDATA/MODIS-Aqua/L3SMI').select('sst') .filterDate(startDate, endDate) .filterBounds(EEZ) ....
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0answers
86 views

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). // ...
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1answer
169 views

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 ...
1
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1answer
197 views

How to read minimum and maximum pixel values of an image in earth engine?

I want to read the minimum and maximum rainfall value for my study region. While using the reducer function I can read the mean value, however, for min and max value it is showing null. I wish to ...
3
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1answer
192 views

ReduceRegions not writting to feature properties in GEE

I am trying to apply reduceRegions to extract average precipitation from the TerraClimate dataset (developers.google.com/earth-engine/datasets/catalog/IDAHO_EPSCOR_TERRACLIMATE) within each polygon of ...
1
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1answer
271 views

Google earth engine: count number of null values per region

Following a previous post I now have some code which sets null values in an image collection to zero. I have used this code on several variables, however, I'd like to know which variables have null ...
0
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1answer
536 views

Difference between reduce(ee.Reducer.mean()) and mean() for ImageCollection in GEE

I am working with S5P data for NO2. I have an image collection and want to obtain the mean NO2 for specified filters. The following code is from the documentation. var collection = ee.ImageCollection('...
1
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1answer
91 views

FeatureCollection (Error) Image.reduceRegions: Group input must come after weighted inputs

I was trying to find the area of each block by category in the band. There is one band and it has 18 categories. The feature collection is a collection of blocks described uniquely by code_2011. var ...
0
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1answer
137 views

Google Earth Engine: Converting raster to vector in the same resolution as the original image

I am using Google Earth Engine to reduce a raster region to polygon vectors. What I want to achieve is: Obtain a set of polygons each of which matches the grid of measurement in the raster dataset. ...
2
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1answer
37 views

Cannot get canopy height from dataset

I just can't work out why this reducer does not work and give me the average canopy height. The reducer output is null even though there are pixels in the area. var fromList = ee.FeatureCollection(&...
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2answers
83 views

Google Earth Engine: Reduce every image in a collection

I want to reduce every single image in a collection, but I have not been able to make it. The process is really easy and works with a single image, but I need to do the same for every image in the ...
0
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1answer
108 views

Google Earth Engine - Dynamic Visualization Parameters

I made a script that calculates the maximum NDVI values of the last 100 days of an area. Therefore, depending on WHEN you run it, the resulting image. Is there any straight straightforward method to ...
0
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1answer
91 views

Export ReduceRegion fixedHistogram toDrive

I'm trying to export a fixed histogram from reduceRegion as a .csv file. I'm sure im missing the obvious here, but can't find a reasonable example that does this straightforward. I can do it as a ...
1
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1answer
140 views

Earth Engine: combining reducers does not give same output as running reducers separately?

I am trying to combine reducers, which according to my understanding, is running parallel yet independent reducers when using sharedInputs: true (see doc). But actually, I notice that with combine(), ...
0
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1answer
159 views

Count number of pixel for each polygon and have the data in one featurecollection [closed]

I have raster with NDVI values. I have calculate for each plot the number of pixels in different values (no. of poixels lower than 0.2, higher than 0.2 and lower than 0.4 ect....) based on masks I ...
2
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2answers
140 views

earthEngine: count number of fully covered pixels within a region

I would like to count the number of pixels that are fully covered by a given region/geometry. How can I do that? Using standard reducer, I can get: ee.Reducer.count() will just count the number of ...
4
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1answer
221 views

Run LandTrendr algorithm on a collection of points/pixels in Earth Engine

Regarding the LandTrendr algorithm in Earth Engine... I have prepared an input image collection and can successfully get a result from the algorithm (no errors), but how can I extract segmentation ...
4
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1answer
474 views

Multiple reducers Google Earth Engine

How can we apply more than 2 reducers to an Image? The following link shows for 2 reducers https://developers.google.com/earth-engine/reducers_intro But the following won't work: // Load a Landsat ...