PixelBlock

Resumen

Defines a group or block of pixels to include for raster processing. The PixelBlockCollection object is made up of one or more PixelBlock objects.

Debate

The PixelBlock object defines a block of pixels within a raster to use for processing. It is used in conjunction with the PixelBlockCollection object to iterate through one or more large rasters for processing.

Sintaxis

PixelBlock
 (data, extent)

Parámetro	Explicación	Tipo de datos
data	A NumPy array containing the pixel values for the pixel block. If the raster is not multidimensional, the shape of the array should be (rows, columns, bands). If the raster is multidimensional, the shape of the array should be (slices, rows, columns, bands).	NumPyArray
extent	The spatial extent of the pixel block.	Extent

Propiedades

Propiedad	Explicación	Tipo de datos
cell_size (Sólo lectura)	The cell size of the pixels in the pixel block. This is a tuple containing the cell size in the x-direction and the y-direction (x-size, y-size).	tuple
tlc (Sólo lectura)	The coordinates of the pixel block's top left corner.	Point
spatial_reference (Sólo lectura)	The spatial reference of the pixel block.	SpatialReference

Descripción general del método

Método	Explicación
getData ()	Returns the NumPy array within the pixel block.

Métodos

getData ()

Valor de retorno

Tipo de datos	Explicación
NumPyArray	The NumPy array object from the pixel block.

Muestra de código

PixelBlock example

Iterates through pixel blocks to calculate the total area of forest in a land cover raster.

import arcpy 

# Specify the input raster
in_raster = arcpy.Raster("landcover.tif")  

# Create a PixelBlockCollection

blockCollection = arcpy.ia.PixelBlockCollection(
	in_raster, pixel_block_size = (512, 512), nodata_to_values = -1) 
forest_cell_count = 0 

# Iterate through each PixelBlock 

try: 
    while True: 
        pixelblock = next(blockCollection) 
        np_array = pixelblock.getData() 
        forest_cell_count+= np.count_nonzero(np_array == 1) # value = 1 is forest class 
except StopIteration: 
    pass 
print ("total forest pixels : " + str(forest_cell_count))