How to print reduced pixel value in google earth engine

Question

I try to print the value of precipitation sum of a given pixel (point location)

 # pixel location
loc_point = ee.Geometry.Point([-0.627983, 52.074361])
# get precip
precip = ee.ImageCollection('NASA/GPM_L3/IMERG_MONTHLY_V06')\
.filterDate('2019-06-01', '2020-06-30')\
.filterBounds(loc_point)\
.select('precipitation')

# sum  
precip_sum = precip.reduce(ee.Reducer.sum())

# print sum precip value
precip_sum.get('precipitation_sum').getInfo()

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score 0 · Answer 1 · answered Jul 19 '20 at 15:42

The reduce operation gets you an image which contains the sum across the image collection; it's a reduction over time, in this case. In order to get the value at a single pixel, you need to use reduceRegion also.

reduceRegion is designed to work on 2D areas, so you do have to specify some things that arent' strictly necessary to define a point:

precip_sum = (precip
  .reduce(ee.Reducer.sum())
  .reduceRegion(
    geometry=loc_point,
    reducer=ee.Reducer.first(),  # take one pixel (there will be only one)
    crs=precip.first().projection()  # doesn't matter but must pick one
  ))

Note: I haven't tested this exact Python; I converted the syntax from this Earth Engine JavaScript which I did test.

How to print reduced pixel value in google earth engine

1 Answers1