Added catchment delineation functions and exposed to Python #53
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@joeperdefloep Nice work! This would be a great addition to the package. |
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ooh,quick reply! some other important notes I forgot to mention previously:
EDIT: so this is caused by the line extending to the edge of the grid... If I make a grid of 6 and then draw a line until y1=4, there is no problem, but an only 0 line. I think this may need some more work...
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reference for better line-drawing, including slopes >1: https://www.geeksforgeeks.org/bresenhams-line-generation-algorithm/ |
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Ok... So I found out that my commit was 45+ commits behind the main branch, which made some things obsolete that I wrote before, and gave some headaches while fixing. It all works now! import richdem as rd
import numpy as np
dem = rd.rdarray(np.array([
[1,2,3,4,5],
[1,2,3,4,5],
[1,2,3,4,5],
[1,2,3,4,5],
[1,2,3,4,5],]),no_data=0)
mask = rd.rdarray(np.array([
[0,0,0,0,0],
[0,0,0,0,0],
[1,0,0,0,0],
[0,0,0,0,0],
[0,0,0,0,0]]),no_data=0)
print(rd.UpslopeCells(dem,mask=mask,method="Quinn"))
print(rd.UpslopeCells(dem,mask=mask,method="mflow"))output: but also a lot of these when I start richdem: and a segfault at the end.
full output:
I think this has something to do with my installation, rather than the PR
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@giswqs Since it didn't get replies or merged quickly, I also implemented it in Cython, albeit less generic: %%cython -+
from libcpp.queue cimport queue
from libcpp.vector cimport vector
from libc.math cimport isnan
cdef struct xypoint:
long x
long y
# 3 2 1
# 4 X 0
# 5 6 7
cdef int[8] dx = [1, 1, 0, -1, -1, -1, 0, 1]
cdef int[8] dy = [0, 1, 1, 1, 0, -1, -1, -1]
def upslope_cells(double[:,:] mask, double[:,:] dem) -> void:
cdef queue[xypoint] qu
for i in range(mask.shape[0]):
for j in range(mask.shape[1]):
if mask[i,j] != 0:
qu.push(xypoint(i,j))
while not qu.empty():
point = qu.front()
qu.pop()
for i in range(8):
x = point.x + dx[i]
y = point.y + dy[i]
if x < 0 or x > mask.shape[0]:
continue
if y < 0 or y > mask.shape[1]:
continue
if mask[x,y] == 0:
if dem[x,y] > dem[point.x,point.y]:
qu.push(xypoint(x,y))
mask[x,y] += 1hope it helps! |
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Added catchment delineation, because I needed it.
edit: Actually, this PR finds all upslope cells, given an input, using multiple possible methods. This is different than catchment delineation, because two catchments can actually overlap if a divergent flow metric is used. That functionality is actually already present in a modified algorithm for depression-filling
I saw that it was a todo, so took the liberty to implement it.
I needed the functionality myself to also use a mask in stead of a line.
some notes, in no particular order:
catchment_delineation.hppfunctions. This is actually important, because the raster should be filled with nodata values in order for the algorithm to work properly. I also do this there, but not super nice yet, because I wrote a 2-liner helper function that only works for 3/4 cases0cells, to give more user flexibility,flowProportionsmethod was fast enough for what I needed. Can add on request. (Also I do not see an easy way to implement Dinf without copying a lot of code)FlowProportions, which includes a redundantcopyFromWrapped, but this seemed easier/more understandable than re-writing.It could be that some documentation for c++ is not fully optimal yet, but I can work on that. For now I just wanted to make this pull request. EDIT: documentation should be rather good.
hope you like it!