Get basic statistics of raster data.

        Args:
            raster_file: raster file path.

        Returns:
            min, max, mean, std.

def raster_statistics(raster_file):
        """Get basic statistics of raster data.

        Args:
            raster_file: raster file path.

        Returns:
            min, max, mean, std.
        """
        ds = gdal_Open(raster_file)
        band = ds.GetRasterBand(1)
        minv, maxv, meanv, std = band.ComputeStatistics(False)
        return minv, maxv, meanv, std