ee.Reducer.count

Renvoie un réducteur qui calcule le nombre d'entrées non nulles. Le cas échéant, le nom de la sortie est "count".

UtilisationRenvoie
ee.Reducer.count()Réducteur

Aucun argument.

Exemples

Éditeur de code (JavaScript)

print(ee.List([]).reduce(ee.Reducer.count()));  // 0
print(ee.List([0]).reduce(ee.Reducer.count()));  // 1
print(ee.List([-1]).reduce(ee.Reducer.count()));  // 1
print(ee.List([1, null, 3]).reduce(ee.Reducer.count()));  // 2
print(ee.List([1, '', 3]).reduce(ee.Reducer.count()));  // 3

print(ee.Array([1, 0, 3]).reduce(ee.Reducer.count(), [0]));  // [3]

var anArray = ee.Array([[1, 0, 3], [1, 2, 3]]);
print(anArray.reduce(ee.Reducer.count(), [0]));  // [[2, 2, 2]]
print(anArray.reduce(ee.Reducer.count(), [1]));  // [[3], [3]]
print(anArray.reduce(ee.Reducer.count(), [1, 0]));  // [[6]]

// Use reduceRegion to apply count().
var elev = ee.Image('CGIAR/SRTM90_V4');
var roi = ee.Geometry.Point([-119.86, 37.74]).buffer(5000);

// Create a mask where elevation is greater than 2000 meters.
var highElevMask = elev.gt(2000);

// Update the image with the mask. Pixels = 0 in the mask become null/masked.
var maskedElev = elev.updateMask(highElevMask);

// Run the count reducer. Masked pixels are ignored.
var highElevCount = maskedElev.reduceRegion({
  reducer: ee.Reducer.count(),
  geometry: roi,
  scale: 90,
  maxPixels: 1e9
});

print('Count of pixels > 2000m:', highElevCount.get('elevation'));  // 20

Configuration de Python

Consultez la page Environnement Python pour en savoir plus sur l'API Python et sur l'utilisation de geemap pour le développement interactif.

import ee
import geemap.core as geemap

Colab (Python)

display(ee.List([]).reduce(ee.Reducer.count()))  # 0
display(ee.List([0]).reduce(ee.Reducer.count()))  # 1
display(ee.List([-1]).reduce(ee.Reducer.count()))  # 1
display(ee.List([1, None, 3]).reduce(ee.Reducer.count()))  # 2
display(ee.List([1, '', 3]).reduce(ee.Reducer.count()))  # 3

display(ee.Array([1, 0, 3]).reduce(ee.Reducer.count(), [0]))  # [3]

an_array = ee.Array([[1, 0, 3], [1, 2, 3]])
display(an_array.reduce(ee.Reducer.count(), [0]))  # [[2, 2, 2]]
display(an_array.reduce(ee.Reducer.count(), [1]))  # [[3], [3]]
display(an_array.reduce(ee.Reducer.count(), [1, 0]))  # [[6]]

# Use reduceRegion to apply count().
elev = ee.Image('CGIAR/SRTM90_V4')
roi = ee.Geometry.Point([-119.86, 37.74]).buffer(5000)

# Create a mask where elevation is greater than 2000 meters.
high_elev_mask = elev.gt(2000)

# Update the image with the mask. Pixels = 0 in the mask become null/masked.
masked_elev = elev.updateMask(high_elev_mask)

# Run the count reducer. Masked pixels are ignored.
high_elev_count = masked_elev.reduceRegion(
    reducer=ee.Reducer.count(),
    geometry=roi,
    scale=90,
    maxPixels=int(1e9)
)

display('Count of pixels > 2000m:', high_elev_count.get('elevation'))  # 20