georaster.py 文件源码

def __init__(self,ds_filename,load_data=True,latlon=True,band=1,
        spatial_ref=None,geo_transform=None,downsampl=1):
        """ Construct object with raster from a single band dataset. 

        Parameters:
            ds_filename : filename of the dataset to import
            load_data : - True, to import the data into obj.r. 
                        - False, to not load any data.
                        - tuple (left, right, bottom, top) to load subset; 
                          obj.extent will be set to reflect subset area.
            latlon : default True. Only used if load_data=tuple. Set as False
                     if tuple is projected coordinates, True if WGS84.
            band : default 1. Specify GDAL band number to load. If you want to
                   load multiple bands at once use MultiBandRaster instead.
            downsampl : default 1. Used to down-sample the image when loading it. 
                A value of 2 for example will multiply the resolution by 2. 

            Optionally, you can manually specify/override the georeferencing. 
            To do this you must set both of the following parameters:

            spatial_ref : a OSR SpatialReference instance
            geo_transform : a Geographic Transform tuple of the form 
                            (top left x, w-e cell size, 0, top left y, 0, 
                             n-s cell size (-ve))

        """

        # Do basic dataset loading - set up georeferencing
        self._load_ds(ds_filename,spatial_ref=spatial_ref,
                      geo_transform=geo_transform)

        # Import band datatype
        band_tmp = self.ds.GetRasterBand(band)
        self.dtype = gdal.GetDataTypeName(band_tmp.DataType)

        # Load entire image
        if load_data == True:
            self.r = self.read_single_band(band,downsampl=downsampl)

        # Or load just a subset region
        elif isinstance(load_data,tuple) or isinstance(load_data,list):
            if len(load_data) == 4:
                self.r = self.read_single_band_subset(load_data,latlon=latlon,
                    band=band,update_info=True,downsampl=downsampl)

        elif load_data == False:
            return

        else:
            print('Warning : load_data argument not understood. No data loaded.')