Code Editor (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');
}
// Create a 1D array image with length 6.
var arrayImg1D = ee.Image([0, 1, 2, 3, 4, 5]).toArray();
print('1D array image (pixel)', sampArrImg(arrayImg1D));
// [0, 1, 2, 3, 4, 5]
// Sum the elements in the 1D array image.
var arrayImg1Dsum = arrayImg1D.arrayReduce(ee.Reducer.sum(), [0]);
print('1D array image sum (pixel)', sampArrImg(arrayImg1Dsum));
// [15]
// Create a 2D array image with 2 rows and 3 columns.
var arrayImg2D = arrayImg1D.arrayReshape(ee.Image([2, 3]).toArray(), 2);
print('2D array image (pixel)', sampArrImg(arrayImg2D));
// [[0, 1, 2],
// [3, 4, 5]]
// Sum 2D array image along 0-axis.
var arrayImg2DsumRow = arrayImg2D.arrayReduce(ee.Reducer.sum(), [0]);
print('2D array image sum rows (pixel)', sampArrImg(arrayImg2DsumRow));
// [[3, 5, 7]]
// Sum 2D array image along 1-axis.
var arrayImg2DsumCol = arrayImg2D.arrayReduce(ee.Reducer.sum(), [1]);
print('2D array image sum columns (pixel)', sampArrImg(arrayImg2DsumCol));
// [[3],
// [12]]
// Sum 2D array image 0-axis and 1-axis.
var arrayImg2DsumRowCol = arrayImg2D.arrayReduce(ee.Reducer.sum(), [0, 1]);
print('2D array image sum columns (pixel)', sampArrImg(arrayImg2DsumRowCol));
// [[15]]
// For reducers that provide several outputs (like minMax and percentile),
// you need to ensure you have a dimension to hold the results. For instance,
// if you want minMax for a 1D array, add a second dimension.
var arrayImg1Dto2D = arrayImg1D.toArray(1);
print('1D array image to 2D', sampArrImg(arrayImg1Dto2D));
// [[0],
// [1],
// [2],
// [3],
// [4],
// [5]]
// Calculate min and max for 2D array, use the fieldAxis parameter.
var minMax1D = arrayImg1Dto2D.arrayReduce(ee.Reducer.minMax(), [0], 1);
print('1D array image minMax (pixel)', sampArrImg(minMax1D));
// [[0, 5]]
// If your array image is 2D and you want min and max, add a third dimension.
var arrayImg2Dto3D = arrayImg2D.toArray(2);
print('2D array image to 3D', sampArrImg(arrayImg2Dto3D));
// [[[0], [1], [2]],
// [[3], [4], [5]]]
// Calculate min and max along the 0-axis, store results in 2-axis.
var minMax2D = arrayImg2Dto3D.arrayReduce(ee.Reducer.minMax(), [0], 2);
print('2D array image minMax (pixel)', sampArrImg(minMax2D));
// [[[0, 3],
// [1, 4],
// [2, 5]]]
Python setup
See the
Python Environment page for information on the Python API and using
geemap
for interactive development.
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')
# Create a 1D array image with length 6.
array_img_1d = ee.Image([0, 1, 2, 3, 4, 5]).toArray()
print('1D array image (pixel):', samp_arr_img(array_img_1d).getInfo())
# [0, 1, 2, 3, 4, 5]
# Sum the elements in the 1D array image.
array_img_1d_sum = array_img_1d.arrayReduce(ee.Reducer.sum(), [0])
print('1D array image sum (pixel):', samp_arr_img(array_img_1d_sum).getInfo())
# [15]
# Create a 2D array image with 2 rows and 3 columns.
array_img_2d = array_img_1d.arrayReshape(ee.Image([2, 3]).toArray(), 2)
print('2D array image (pixel):', samp_arr_img(array_img_2d).getInfo())
# [[0, 1, 2],
# [3, 4, 5]]
# Sum 2D array image along 0-axis.
array_img_2d_sum_row = array_img_2d.arrayReduce(ee.Reducer.sum(), [0])
print(
'2D array image sum rows (pixel):',
samp_arr_img(array_img_2d_sum_row).getInfo()
)
# [[3, 5, 7]]
# Sum 2D array image along 1-axis.
array_img_2d_sum_col = array_img_2d.arrayReduce(ee.Reducer.sum(), [1])
print(
'2D array image sum columns (pixel):',
samp_arr_img(array_img_2d_sum_col).getInfo()
)
# [[3],
# [12]]
# Sum 2D array image 0-axis and 1-axis.
array_img_2d_sum_row_col = array_img_2d.arrayReduce(ee.Reducer.sum(), [0, 1])
print(
'2D array image sum columns (pixel):',
samp_arr_img(array_img_2d_sum_row_col).getInfo()
)
# [[15]]
# For reducers that provide several outputs (like minMax and percentile),
# you need to ensure you have a dimension to hold the results. For instance,
# if you want minMax for a 1D array, add a second dimension.
array_img_1d_to_2d = array_img_1d.toArray(1)
print('1D array image to 2D:', samp_arr_img(array_img_1d_to_2d).getInfo())
# [[0],
# [1],
# [2],
# [3],
# [4],
# [5]]
# Calculate min and max for 2D array, use the fieldAxis parameter.
min_max_1d = array_img_1d_to_2d.arrayReduce(ee.Reducer.minMax(), [0], 1)
print('1D array image minMax (pixel):', samp_arr_img(min_max_1d).getInfo())
# [[0, 5]]
# If your array image is 2D and you want min and max, add a third dimension.
array_img_2d_to_3d = array_img_2d.toArray(2)
print('2D array image to 3D:', samp_arr_img(array_img_2d_to_3d).getInfo())
# [[[0], [1], [2]],
# [[3], [4], [5]]]
# Calculate min and max along the 0-axis, store results in 2-axis.
min_max_2d = array_img_2d_to_3d.arrayReduce(ee.Reducer.minMax(), [0], 2)
print('2D array image minMax (pixel):', samp_arr_img(min_max_2d).getInfo())
# [[[0, 3],
# [1, 4],
# [2, 5]]]