PyQGIS Implementation of generating raster statistics
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| import numpy as np | |
| from PyQt5.QtCore import QFileInfo | |
| import gdal | |
| import osr | |
| from PyQt5.QtGui import QColor | |
| import processing | |
| __author__ = 'admire' | |
| from qgis.core import QgsRasterShader, QgsColorRampShader, QgsSingleBandPseudoColorRenderer, \ | |
| QgsProject, QgsRasterLayer, \ | |
| QgsRasterBandStats, QgsCoordinateReferenceSystem | |
| class ReportClass(object): | |
| def __init__(self): | |
| self.colour_ramp = {} | |
| def mini_style(self, layer): | |
| raster_shader = QgsRasterShader() | |
| color_ramp = QgsColorRampShader() | |
| color_ramp.setColorRampItemList(self.colour_ramp['ramp']) | |
| color_ramp.setColorRampType(QgsColorRampShader.Interpolated) | |
| raster_shader.setRasterShaderFunction(color_ramp) | |
| my_pseudo_renderer = QgsSingleBandPseudoColorRenderer(layer.dataProvider(), | |
| layer.type(), | |
| raster_shader) | |
| layer.setRenderer(my_pseudo_renderer) | |
| layer.triggerRepaint() | |
| QgsProject.instance().addMapLayer(layer, True) | |
| if layer.isValid() is True: | |
| print("Layer was loaded successfully") | |
| else: | |
| print("Unable to read basename and file path - Your string is probably invalid") | |
| def get_area(self, raster_path): | |
| raster_layer = QgsRasterLayer(raster_path) | |
| colour_ranges = self.colour_ramp['ranges'] | |
| colours = self.colour_ramp['colours'] | |
| area_per_colour = {} | |
| # open the raster | |
| ds = gdal.Open(raster_path) | |
| if ds is None: | |
| gdal.sys.exit("ERROR: can't open raster") | |
| # get cell sizes | |
| # TODO: Add this piece of code correctly | |
| pixel_size_x = raster_layer.rasterUnitsPerPixelX() | |
| pixel_size_y = raster_layer.rasterUnitsPerPixelY() | |
| hectare_per_cell = pixel_size_x * pixel_size_y / 10000 | |
| # get raster bands | |
| # hectare_per_cell = 225 | |
| raster = ds.ReadAsArray() | |
| # process the raster | |
| for (bottom, top, colour) in zip([-1] + colour_ranges[:-1], colour_ranges, colours): | |
| # TODO: break up | |
| # TODO: convert to method | |
| # TODO: test | |
| raster = np.where(raster != -9999, raster, np.nan) | |
| # print top | |
| # print np.nanmin(raster) | |
| raster_bounds = np.where(top >= raster, raster, np.nan) | |
| # print np.nansum(raster_bounds) | |
| lower_bounds = np.where(raster_bounds > bottom, 1, np.nan) | |
| classified_area = np.nansum(lower_bounds) | |
| # print classified_area | |
| if np.isnan(classified_area): | |
| classified_area = 0 | |
| area_per_colour[colour] = round(hectare_per_cell * classified_area, 2) | |
| # print area_per_colour | |
| return area_per_colour | |
| def get_raster_area(self, raster_path): | |
| raster_layer = QgsRasterLayer(raster_path) | |
| ds = gdal.Open(raster_path) | |
| if ds is None: | |
| gdal.sys.exit("ERROR: can't open raster") | |
| # get cell sizes | |
| raster_band = ds.GetRasterBand(1) | |
| no_data_value = raster_band.GetNoDataValue() | |
| if no_data_value is None: | |
| no_data_value = -9999 | |
| else: | |
| no_data_value = no_data_value | |
| # TODO: Add this piece of code correctly | |
| pixel_size_x = raster_layer.rasterUnitsPerPixelX() | |
| pixel_size_y = raster_layer.rasterUnitsPerPixelY() | |
| hectare_per_cell = pixel_size_x * pixel_size_y / 10000 | |
| raster = ds.ReadAsArray() | |
| all_pixels_1 = np.where(raster != no_data_value, 1, np.nan) | |
| total_pixel_area = np.nansum(all_pixels_1) | |
| total_area_raster = total_pixel_area * hectare_per_cell | |
| return total_area_raster | |
| # function to style raster layers dynamically | |
| def style_raster(self, raster_path): | |
| file_info = QFileInfo(raster_path) | |
| path = file_info.filePath() | |
| basename = file_info.baseName() | |
| layer = QgsRasterLayer(path, basename) | |
| provider = layer.dataProvider() | |
| extent = layer.extent() | |
| ver = provider.hasStatistics(1, QgsRasterBandStats.All) | |
| stats = provider.bandStatistics(1, QgsRasterBandStats.All, extent, 0) | |
| self.colour_ramp = {'colours': [], 'ranges': [], 'ramp': []} | |
| if ver is not False: | |
| print("minimumValue = ", stats.minimumValue) | |
| print("maximumValue = ", stats.maximumValue) | |
| if stats.minimumValue < 0: | |
| minimum = 0 | |
| else: | |
| minimum = int(stats.minimumValue) | |
| maximum = int(stats.maximumValue) | |
| raster_range = maximum - minimum | |
| total_area_raster = self.get_raster_area(raster_path) | |
| print(total_area_raster) | |
| print(" 6 classes generated") | |
| colours = ['#33a02c', '#80c02e', '#cee130', '#f1c62c', '#ea7024', | |
| '#e31a1c'] | |
| add = raster_range // (len(colours) - 1) | |
| int_1 = int(minimum + add) | |
| int_2 = int(int_1 + add) | |
| int_3 = int(int_2 + add) | |
| int_4 = int(int_3 + add) | |
| value_list = [minimum, int_1, int_2, int_3, int_4, maximum] | |
| self.colour_ramp['colours'] = colours | |
| self.colour_ramp['ranges'] = value_list | |
| area_per_colour = self.get_area(raster_path) | |
| percentage_0 = round(((area_per_colour[colours[0]] / total_area_raster) * 100), 2) | |
| percentage_1 = round(((area_per_colour[colours[1]] / total_area_raster) * 100), 2) | |
| percentage_2 = round(((area_per_colour[colours[2]] / total_area_raster) * 100), 2) | |
| percentage_3 = round(((area_per_colour[colours[3]] / total_area_raster) * 100), 2) | |
| percentage_4 = round(((area_per_colour[colours[4]] / total_area_raster) * 100), 2) | |
| percentage_5 = round(((area_per_colour[colours[5]] / total_area_raster) * 100), 2) | |
| self.colour_ramp['ramp'] = ( | |
| QgsColorRampShader.ColorRampItem(value_list[0], QColor(colours[0]), lbl=str('%d (%s ha - %s %%)' % ( | |
| value_list[0], area_per_colour[colours[0]], percentage_0))), | |
| QgsColorRampShader.ColorRampItem(value_list[1], QColor(colours[1]), | |
| lbl='%d - %d (%s ha - %s %%)' % ( | |
| value_list[0] + 1, | |
| value_list[1], | |
| area_per_colour[colours[1]], percentage_1)), | |
| QgsColorRampShader.ColorRampItem(value_list[2], QColor(colours[2]), | |
| lbl='%d - %d (%s ha - %s %%)' % ( | |
| value_list[1] + 1, | |
| value_list[2], | |
| area_per_colour[colours[2]], percentage_2)), | |
| QgsColorRampShader.ColorRampItem(value_list[3], QColor(colours[3]), | |
| lbl='%d - %d (%s ha - %s %%)' % ( | |
| value_list[2] + 1, | |
| value_list[3], | |
| area_per_colour[colours[3]], percentage_3)), | |
| QgsColorRampShader.ColorRampItem(value_list[4], QColor(colours[4]), | |
| lbl='%d - %d (%s ha - %s %%)' % ( | |
| value_list[3] + 1, | |
| value_list[4], | |
| area_per_colour[colours[4]], percentage_4)), | |
| QgsColorRampShader.ColorRampItem(value_list[5], QColor(colours[5]), | |
| lbl='%d - %d (%s ha - %s %%)' % ( | |
| value_list[4] + 1, | |
| value_list[5], | |
| area_per_colour[colours[5]], percentage_5))) | |
| self.mini_style(layer) | |
| # function to determine utm zones | |
| def crs_zone(self, raster_path): | |
| data = gdal.Open(raster_path, gdal.GA_ReadOnly) | |
| if data is None: | |
| print("Raster layer not valid") | |
| else: | |
| projection = osr.SpatialReference(wkt=data.GetProjection()) | |
| epsg_code = projection.GetAttrValue('AUTHORITY', 1) | |
| return epsg_code | |
| # Main function that has all the logic | |
| def run(self): | |
| raster = '/tmp/S34E020.hgt' | |
| eps_code = self.crs_zone(raster) | |
| if eps_code == '4326': | |
| projected_raster = processing.run("gdal:warpreproject", {'INPUT': '%s' % raster, 'SOURCE_CRS': None, | |
| 'TARGET_CRS': QgsCoordinateReferenceSystem( | |
| 'EPSG:3857'), 'RESAMPLING': 0, 'NODATA': None, | |
| 'TARGET_RESOLUTION': None, | |
| 'OPTIONS': 'COMPRESS=DEFLATE|PREDICTOR=2|ZLEVEL=9', | |
| 'DATA_TYPE': 0, 'TARGET_EXTENT': None, | |
| 'TARGET_EXTENT_CRS': None, 'MULTITHREADING': True, | |
| 'EXTRA': '', | |
| 'OUTPUT': 'TEMPORARY_OUTPUT'}) | |
| raster_path = projected_raster.get('OUTPUT') | |
| if not raster_path: | |
| raise Exception('Raster was not reprojected') | |
| else: | |
| raster_path = raster | |
| print("The raster layer that is generated is:" + raster_path) | |
| self.style_raster(raster_path) | |
| self.get_area(raster_path) | |
| reporter = ReportClass() | |
| reporter.run() | |
| "" |
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should work for both, mind you this was written for QGIS2, you might need to port it to QGIS 3