ee.Image.arrayReduce

    Reduces elements of each array pixel.
    Usage Returns
    Image. arrayReduce (reducer, axes, fieldAxis ) Image
    Argument Type Details
    this: input
    		Image Input image.
    reducer
    		Reducer The reducer to apply.
    axes
    		List The list of array axes to reduce in each pixel. The output will have a length of 1 in all these axes.
    fieldAxis
    		Integer, default: null The axis for the reducer's input and output fields. Only required if the reducer has multiple inputs or outputs.

    Examples

    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]]]
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