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Remove color function from flood fill because it is redundant #766

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Merged
merged 3 commits into from
Oct 15, 2020
+23 −57
Merged

Remove color function from flood fill because it is redundant #766

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d4ce5bf
fixing unnecessary color function
leios Oct 13, 2020
325988f
fixing line numbers
leios Oct 13, 2020
82abae9
removing binary file
leios Oct 15, 2020
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12 changes: 3 additions & 9 deletions contents/flood_fill/code/c/flood_fill.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,12 +25,6 @@ int inbounds(struct point p, struct canvas c) {
return (p.x < 0 || p.y < 0 || p.y >= c.max_y || p.x >= c.max_x) ? 0 : 1;
}

void color(struct canvas c, struct point p, int old_val, int new_val) {
if (inbounds(p, c) && c.data[p.x + c.max_x * p.y] == old_val) {
c.data[p.x + c.max_x * p.y] = new_val;
}
}

int find_neighbors(struct canvas c, struct point p, int old_val, int new_val,
struct point *neighbors) {
int cnt = 0;
Expand Down Expand Up @@ -93,7 +87,7 @@ void stack_fill(struct canvas c, struct point p, int old_val, int new_val) {
while (!stack_empty(stk)) {
struct point cur_loc = stack_pop(&stk);
if (c.data[cur_loc.x + c.max_x * cur_loc.y] == old_val) {
color(c, cur_loc, old_val, new_val);
c.data[cur_loc.x + c.max_x * cur_loc.y] = new_val;

struct point neighbors[4];
int cnt = find_neighbors(c, cur_loc, old_val, new_val, neighbors);
Expand Down Expand Up @@ -163,7 +157,7 @@ void queue_fill(struct canvas c, struct point p, int old_val, int new_val) {
while (!queue_empty(q)) {
struct point cur_loc = dequeue(&q);
if (c.data[cur_loc.x + c.max_x * cur_loc.y] == old_val) {
color(c, cur_loc, old_val, new_val);
c.data[cur_loc.x + c.max_x * cur_loc.y] = new_val;

struct point neighbors[4];
int cnt = find_neighbors(c, cur_loc, old_val, new_val, neighbors);
Expand All @@ -184,7 +178,7 @@ void recursive_fill(struct canvas c, struct point p, int old_val,
return;
}

color(c, p, old_val, new_val);
c.data[p.x + c.max_x * p.y] = new_val;

struct point neighbors[4];
int cnt = find_neighbors(c, p, old_val, new_val, neighbors);
Expand Down
22 changes: 4 additions & 18 deletions contents/flood_fill/code/julia/flood_fill.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -20,20 +20,6 @@ function inbounds(canvas_size, loc)
end
end

function color!(canvas, loc::CartesianIndex, old_val, new_val)
# bounds check, do not color if no in bounds!
if !inbounds(size(canvas), loc)
return
end

# Only change color if the element value is the old value
if (canvas[loc] != old_val)
return
else
canvas[loc] = new_val
end
end

function find_neighbors(canvas, loc::CartesianIndex, old_val, new_val)

# Finding north, south, east, west neighbors
Expand Down Expand Up @@ -65,7 +51,7 @@ function stack_fill!(canvas, loc::CartesianIndex, old_val, new_val)
while length(s) > 0
current_loc = pop!(s)
if canvas[current_loc] == old_val
color!(canvas, current_loc, old_val, new_val)
canvas[current_loc] = new_val
possible_neighbors = find_neighbors(canvas, current_loc,
old_val, new_val)
for neighbor in possible_neighbors
Expand All @@ -86,7 +72,7 @@ function queue_fill!(canvas, loc::CartesianIndex, old_val, new_val)
enqueue!(q, loc)

# Coloring the initial location
color!(canvas, loc, old_val, new_val)
canvas[loc] = new_val

while length(q) > 0
current_loc = dequeue!(q)
Expand All @@ -96,7 +82,7 @@ function queue_fill!(canvas, loc::CartesianIndex, old_val, new_val)

# Coloring as we are enqueuing neighbors
for neighbor in possible_neighbors
color!(canvas, neighbor, old_val, new_val)
canvas[neighbor] = new_val
enqueue!(q,neighbor)
end

Expand All @@ -109,7 +95,7 @@ function recursive_fill!(canvas, loc::CartesianIndex, old_val, new_val)
return
end

color!(canvas, loc, old_val, new_val)
canvas[loc] = new_val

possible_neighbors = find_neighbors(canvas, loc, old_val, new_val)
for possible_neighbor in possible_neighbors
Expand Down
11 changes: 4 additions & 7 deletions contents/flood_fill/code/python/flood_fill.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,9 +7,6 @@
def inbounds(canvas_shape, p):
return min(p) >= 0 and p.x < canvas_shape[0] and p.y < canvas_shape[1]

def color(canvas, p, new_val):
canvas[p] = new_val

def find_neighbors(canvas, p, old_val, new_val):
# north, south, east, west neighbors
possible_neighbors = [
Expand All @@ -35,7 +32,7 @@ def stack_fill(canvas, p, old_val, new_val):

while stack:
cur_loc = stack.pop()
color(canvas, cur_loc, new_val)
canvas[cur_loc] = new_val
stack += find_neighbors(canvas, cur_loc, old_val, new_val)

def queue_fill(canvas, p, old_val, new_val):
Expand All @@ -45,21 +42,21 @@ def queue_fill(canvas, p, old_val, new_val):
q = Queue()
q.put(p)

color(canvas, p, new_val)
canvas[p] = new_val

while not q.empty():
cur_loc = q.get()
neighbors = find_neighbors(canvas, cur_loc, old_val, new_val)

for neighbor in neighbors:
color(canvas, neighbor, new_val)
canvas[neighbor] = new_val
q.put(neighbor)

def recursive_fill(canvas, p, old_val, new_val):
if old_val == new_val:
return

color(canvas, p, new_val)
canvas[p] = new_val

neighbors = find_neighbors(canvas, p, old_val, new_val)
for neighbor in neighbors:
Expand Down
35 changes: 12 additions & 23 deletions contents/flood_fill/flood_fill.md
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Expand Up @@ -87,11 +87,11 @@ In code, this might look like this:

{% method %}
{% sample lang="jl" %}
[import:37-55, lang:"julia"](code/julia/flood_fill.jl)
[import:23-41, lang:"julia"](code/julia/flood_fill.jl)
{% sample lang="c" %}
[import:34-52, lang:"c"](code/c/flood_fill.c)
[import:28-46, lang:"c"](code/c/flood_fill.c)
{% sample lang="py" %}
[import:13-28, lang="python"](code/python/flood_fill.py)
[import:10-25, lang="python"](code/python/flood_fill.py)
{% endmethod %}


Expand All @@ -105,22 +105,11 @@ In code, it might look like this:

{% method %}
{% sample lang="jl" %}
[import:106-118, lang:"julia"](code/julia/flood_fill.jl)
[import:92-104, lang:"julia"](code/julia/flood_fill.jl)
{% sample lang="c" %}
[import:180-195, lang:"c"](code/c/flood_fill.c)
[import:174-189, lang:"c"](code/c/flood_fill.c)
{% sample lang="py" %}
[import:58-66, lang="python"](code/python/flood_fill.py)
{% endmethod %}

All code snippets for this chapter rely on an exterior `color` function, defined as

{% method %}
{% sample lang="jl" %}
[import:23-35, lang:"julia"](code/julia/flood_fill.jl)
{% sample lang="c" %}
[import:28-32, lang:"c"](code/c/flood_fill.c)
{% sample lang="py" %}
[import:10-11, lang="python"](code/python/flood_fill.py)
[import:55-63, lang="python"](code/python/flood_fill.py)
{% endmethod %}

The above code continues recursing through available neighbors as long as neighbors exist, and this should work so long as we are adding the correct set of neighbors.
Expand All @@ -129,11 +118,11 @@ Additionally, it is possible to do the same type of traversal by managing a stac

{% method %}
{% sample lang="jl" %}
[import:57-77, lang:"julia"](code/julia/flood_fill.jl)
[import:43-63, lang:"julia"](code/julia/flood_fill.jl)
{% sample lang="c" %}
[import:85-108, lang:"c"](code/c/flood_fill.c)
[import:79-102, lang:"c"](code/c/flood_fill.c)
{% sample lang="py" %}
[import:30-39, lang="python"](code/python/flood_fill.py)
[import:27-36, lang="python"](code/python/flood_fill.py)
{% endmethod %}

This is ultimately the same method of traversal as before; however, because we are managing our own data structure, there are a few distinct differences:
Expand Down Expand Up @@ -170,11 +159,11 @@ The code would look something like this:

{% method %}
{% sample lang="jl" %}
[import:80-104, lang:"julia"](code/julia/flood_fill.jl)
[import:66-90, lang:"julia"](code/julia/flood_fill.jl)
{% sample lang="c" %}
[import:155-178, lang:"c"](code/c/flood_fill.c)
[import:149-172, lang:"c"](code/c/flood_fill.c)
{% sample lang="py" %}
[import:41-56, lang="python"](code/python/flood_fill.py)
[import:38-53, lang="python"](code/python/flood_fill.py)
{% endmethod %}

Now, there is a small trick in this code that must be considered to make sure it runs optimally.
Expand Down