Understanding this implementation of A-star algorithm in Python

Question

I am new to Python. I have this Code with me http://code.activestate.com/recipes/577519-a-star-shortest-path-algorithm/history/1/

its the A star algorithm code. I wanted to know how exactly is it generating the obstacles. Basically I have a black and white image. My task is to reach the end point from the start point avoiding the white spaces. Please help me Thank you!

I have an image. I have its pixels. All I want to do is find the path avoiding white region. How do you suggest I go about? — Jeet Mody
– Jeet Mody, Commented Apr 24, 2014 at 7:34

smci · Accepted Answer · 2014-04-24 07:28:59Z

2

The path-finding algorithm in function pathFind() is well-commented and decomposed. If there's something specific confusing you, tell us what it is. The important lines are after # generate moves (child nodes) in all possible directions, which admittedly is dense code and not very OO.

I suggest you reduce the parameters (m,n) to a 4x5 or 5x6 then step through its execution, either with pdb debugger (single-step or set breakpoints at key points), or hacking in as many print statements as you need:

# map matrix
n = 30 # horizontal size
m = 30 # vertical size

First try giving it your own custom maps to get a feel for how it works (modify the # fillout the map matrix... lines). Then run it interactively in the debugger.

edited Apr 24, 2014 at 7:28

answered Apr 24, 2014 at 7:23

smci

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2 Comments

Jeet Mody Over a year ago

Thanks a lot. I was foing the correct thing, but I was using a different image :P

smci Over a year ago

I don't understand, did you solve your question? or not?

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