"""This module contains the FlowObject class.
"""
from .grid_object import GridObject
import numpy as np
import matplotlib.pyplot as plt
# Add future flow functions here
# pylint: disable=import-error
# from ._flow import ( # type: ignore
# flow_somefuncname
# )
# pylint: disable=import-error
from ._grid import ( # type: ignore
grid_fillsinks,
grid_identifyflats,
grid_gwdt,
grid_gwdt_computecosts,
grid_flow_routing_d8_carve,
grid_flow_routing_targets
)
__all__ = ['FlowObject']
[docs]
class FlowObject():
"""A class containing containing (water-) flow information about a given
digital elevation model (DEM).
"""
[docs]
def __init__(self, grid: GridObject):
"""The constructor for the FlowObject. Takes a GridObject as input,
computes flow direction information and saves them as an FlowObject.
Parameters
----------
grid : GridObject
The GridObject that will be the basis of the computation.
Notes
-----
Large intermediate arrays are created during the initialization
process, which could lead to issues when using very large DEMs.
"""
dims = grid.shape
dem = grid.z
filled_dem = np.zeros_like(dem, dtype=np.float32, order='F')
grid_fillsinks(filled_dem, dem, dims)
flats = np.zeros_like(dem, dtype=np.int32, order='F')
grid_identifyflats(flats, filled_dem, dims)
costs = np.zeros_like(dem, dtype=np.float32, order='F')
conncomps = np.zeros_like(dem, dtype=np.int64, order='F')
grid_gwdt_computecosts(costs, conncomps, flats, dem, filled_dem, dims)
dist = np.zeros_like(flats, dtype=np.float32, order='F')
prev = conncomps # prev: dtype=np.int64
heap = np.zeros_like(flats, dtype=np.int64, order='F')
back = np.zeros_like(flats, dtype=np.int64, order='F')
grid_gwdt(dist, prev, costs, flats, heap, back, dims)
source = heap # source: dtype=np.int64
direction = np.zeros_like(dem, dtype=np.uint8, order='F')
grid_flow_routing_d8_carve(
source, direction, filled_dem, dist, flats, dims)
target = back # target: dtype=int64
grid_flow_routing_targets(target, source, direction, dims)
# TODO: use 'del' to immediately delete unused large arrays?
self.path = grid.path
self.name = grid.name
# raster metadata
self.z = dem
self.target = target
self.source = source
self.shape = grid.shape
# georeference
self.bounds = grid.bounds
self.transform = grid.transform
self.crs = grid.crs
[docs]
def show(self, cmap: str = 'terrain'):
"""
Display the FlowObject instance as an image using Matplotlib.
Parameters
----------
cmap : str, optional
Matplotlib colormap that will be used in the plot.
"""
fig, axs = plt.subplots(1, 3, figsize=(15, 5))
axs[0].imshow(self.z, cmap=cmap)
axs[0].set_title('dem')
axs[1].imshow(self.target, cmap=cmap)
axs[1].set_title('target')
axs[2].imshow(self.source, cmap=cmap)
axs[2].set_title('source')
plt.tight_layout()
plt.show()
# TODO: Add magic functions, maybe use mixins to reuse GridObject functions
