ee.Image.arrayLength

Renvoie la longueur du tableau de chaque pixel le long de l'axe donné.

Utilisation	Renvoie
Image.arrayLength(axis)	Image

Argument	Type	Détails
ceci : input	Image	Image d'entrée.
axis	Nombre entier	Axe le long duquel prendre la longueur.

Exemples

Éditeur de code (JavaScript)

// A function to print arrays for a selected pixel in the following examples.
function sampArrImg(arrImg) {
  var point = ee.Geometry.Point([-121, 42]);
  return arrImg.sample(point, 500).first().get('array');
}

// A 3-band image of constants.
var img = ee.Image([0, 1, 2]);
print('3-band image', img);

// Convert the 3-band image to a 2D array image.
var arrayImg2D = img.toArray().toArray(1);
print('2D array image (pixel)', sampArrImg(arrayImg2D));
// [[0],
//  [1],
//  [2]]

// Get the number of dimensions in each pixel's array.
var arrayImg2Ddim = arrayImg2D.arrayDimensions();
print('N dimensions in array', sampArrImg(arrayImg2Ddim));
// 2

// Get the array length per dimension per pixel.
var arrayImg2DdimLen = arrayImg2D.arrayLengths();
print('Array length per dimension', sampArrImg(arrayImg2DdimLen));
// [3, 1]

// Get the array length for 0-axis (rows).
var arrayImg2Daxis0Len = arrayImg2D.arrayLength(0);
print('Array length 0-axis (rows)', sampArrImg(arrayImg2Daxis0Len));
// 3

// Get the array length for 1-axis (columns).
var arrayImg2Daxis1Len = arrayImg2D.arrayLength(1);
print('Array length 1-axis (columns)', sampArrImg(arrayImg2Daxis1Len));
// 1

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)

# A function to print arrays for a selected pixel in the following examples.
def samp_arr_img(arr_img):
  point = ee.Geometry.Point([-121, 42])
  return arr_img.sample(point, 500).first().get('array')

# A 3-band image of constants.
img = ee.Image([0, 1, 2])
print('3-band image:', img.getInfo())

# Convert the 3-band image to a 2D array image.
array_img_2d = img.toArray().toArray(1)
print('2D array image (pixel):', samp_arr_img(array_img_2d).getInfo())
# [[0],
#  [1],
#  [2]]

# Get the number of dimensions in each pixel's array.
array_img2d_dim = array_img_2d.arrayDimensions()
print('N dimensions in array:', samp_arr_img(array_img2d_dim).getInfo())
# 2

# Get the array length per dimension per pixel.
array_img_2d_dim_len = array_img_2d.arrayLengths()
print(
    'Array length per dimension:',
    samp_arr_img(array_img_2d_dim_len).getInfo()
)
# [3, 1]

# Get the array length for 0-axis (rows).
array_img2d_axis0_len = array_img_2d.arrayLength(0)
print(
    'Array length 0-axis (rows):',
    samp_arr_img(array_img2d_axis0_len).getInfo()
)
# 3

# Get the array length for 1-axis (columns).
array_img_2d_axis1_len = array_img_2d.arrayLength(1)
print(
    'Array length 1-axis (columns):',
    samp_arr_img(array_img_2d_axis1_len).getInfo()
)
# 1