How to accelerate my python looping process for A-star pathfinding? - python-2.7

Question

I try to make an A-star Pathfinding program base on tile-graph (image raster data as graph) where each pixel values represent as cost.. This is my A-star function script so far :
def A_star(h,c,dx,dy,u,s_id,e_id,Op,Cl,Prt,CC,o,ht,w):
Op.append(s_id)
while e_id not in Op :
if Op == [ ] :
break
candidate = { }
for i in Op :
d = {i : CC[i]}
candidate.update(d)
o = min(candidate, key=candidate.get)
Cl.append(o)
Op.remove(o)
adjacent_list = adjacent_cell(o,dx,dy )
for p in adjacent_list :
if p in Cl:
adjacent_list = filter(lambda i: i != p, adjacent_list)
elif p not in Op :
Op.append(p)
d = {p : o }
Prt.update(d)
d = {p : F(p,o,h,u,w,c,dx,e_id,ht,CC)}
CC.update(d)
elif id in Op :
f1 = F(p,o,h,u,w,c,dx,e_id,ht,CC)
f2 = F(p,Prt[p],h,u,w,c,dx,e_id,ht,CC)
if f1 < f2 :
d = {p : o }
Prt.update(d)
d = {id : F(p,o,h,u,w,c,dx,e_id,ht,CC)}
CC.update(d)
return Prt
my sample code and input data can be downloaded here
https://drive.google.com/open?id=0B2zjTfTukbMvaV9BalU4ZGx4MjQ
If i use a small resolution of DEM, 25x29 ( srtm1.tif ), this program goes well. But if i try a large resolution of DEM, for example 1228 x 972 ( dem,asc ). This program took very long time to calculate a whole cell. I guest that the problem is on the looping progress where i try to use loop for iteration (Line 110, A-star function).
while e_id not in Op :
Is there any solution to make my code run faster ?
All kind of help, suggestion, comment, solution will be very appreciate..

Answer 1

some of optimizing will be like this:
def A_star(h,c,dx,dy,u,s_id,e_id,Op,Cl,Prt,CC,o,ht,w):
Op.append(s_id)
continu = e_id not in Op
while continu :
if Op == []:
break
candidate = {i:CC[i] for i in Op } # HERE
o = min(candidate.values()) # HERE
Cl.append(o)
Op.remove(o)
adjacent_list = adjacent_cell(o,dx,dy )
for p in adjacent_list :
if p in Cl:
adjacent_list = filter(lambda i: i != p, adjacent_list)
elif p not in Op :
Op.append(p)
if p==e_id:
continu=False # this will stop while from looping!
Prt[p]=o # HERE
CC[p]=F(p,o,h,u,w,c,dx,e_id,ht,CC) # HERE
elif id in Op :
f1 = F(p,o,h,u,w,c,dx,e_id,ht,CC)
f2 = F(p,Prt[p],h,u,w,c,dx,e_id,ht,CC)
if f1 < f2 :
Prt[p]=o # HERE
CC[id]= F(p,o,h,u,w,c,dx,e_id,ht,CC) # HERE
return Prt
using dict.update is not for setting one item! use dict[key]=value instead.
another help is to check when the p == e_id so if it added to Op the while will stopped!