AStar | fast 2D path finding library based on the A * algorithm | Learning library
kandi X-RAY | AStar Summary
kandi X-RAY | AStar Summary
A fast 2D path finding library based on the A* algorithm. Works with both grids and graphs. Supports any .NET variant that supports .NETStandard 2.0 or higher. This library has no external dependencies. The library is licensed under the MIT license, see the LICENSE file for more details. A* is a greedy, graph based, path finding algorithm. It works by using a heuristic to guide the traveral along the graph. In this library we use the Euclidian distance heuristic. For a comprehensive overview of how the A* algorithm works I recommend this interactive article by Red Blob Games.
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Currently covering the most popular Java, JavaScript and Python libraries. See a Sample of AStar
AStar Key Features
AStar Examples and Code Snippets
def astar(world, start, goal):
"""
Implementation of a start algorithm
world : Object of the world object
start : Object of the cell as start position
stop : Object of the cell as goal position
>>> p = Gridworld()
Community Discussions
Trending Discussions on AStar
QUESTION
I have built an A* Pathfinding algorithm that finds the best route from Point A to Point B, there is a timer that starts and ends post execute of the algorithm and the path is draw, this is parsed to a global variable. so it is accessable when i run the alogrithm more than once (to gain an average time).
the global variable gets added to a list, except when i run the algorithm 5 times, only 4 values get added (I can see 5 times being recorded as the algorithm prints the time after completion). when displaying the list it always misses the first time, and only has times 2,3,4,5 if i run the algorithm 5 times. here is main.py
ANSWER
Answered 2022-Apr-08 at 19:15EDIT:
the misterious 5th print is coming from this line, of course
QUESTION
How do I make an enemy stop at a certain distance from the player rather than going right to it? I want to create a ranged unit. I can do the enemy attacks, I just don't want the enemy to go directly to the player. I have a custom AI script on my enemy using the AStar pathfinding package -
...ANSWER
Answered 2022-Mar-28 at 14:45The correct way would be to not search for a specific node, but any node within some distance from the target, or any node within some distance and with a direct line of sight.
It looks like the AStar pathfinding library should have functions for things like that. There is for example a GetNearest overload that takes a constraint that might work. Or the maxNearestNodeDistance
field. But I'm not familiar with that library, so I have difficulty providing specific suggestions.
Another alternative would be to just write your own implementation. This is not trivial, but also not overly complex, and there are plenty of resources explaining algorithms like A*. You will probably not reach feature parity with a commercial library, but you might only need fairly simple functionality. It might also be useful as a learning exercise to get better knowledge on how AI and path finding works.
QUESTION
I'm using PriorityQueue
and i've implemented comparable class, with compareTo method,
Now i want to know if my queue is sorted, if i use poll()
method will this return the queue of the minimum costSum?
Class: State.java
...ANSWER
Answered 2022-Mar-23 at 09:15Now i want to know if my queue is sorted, if i use poll() method will this return the queue of the minimum costSum?
The Javadoc describes this:
The head of this queue is the least element with respect to the specified ordering. ... The queue retrieval operations poll, remove, peek, and element access the element at the head of the queue.
So, yes, it is the minimum element.
Note, however, that the queue isn't internally sorted: if you print a priority queue, you may note that they do not appear in ascending order. The elements are simply stored in an order with the heap property, which allows efficient updating of the data structure once the minimum element is removed.
QUESTION
So, I do understand depth-first-search is not appropriate for this problem and something like UCS or Astar would be a lot better, just attempting to see if it is possible with a DFS approach.
I need to find a path within a cost budget, my approach using dfs is to keep the cost to get to the next node in the stack as they get pushed, and if going to the next node exceeds, it ignores does not push.
The problem I am facing is that when the budget is exceeded, I am struggling to find a way to set the nodes that have led to this path to be set back as unvisited so newer paths can consider them. I feel it has something to do with setting visited/unvisited properly and have tested a couple but in a bigger graph input, it always fails to find a path within constraint (Have confirmed that it exist using other methods)
...ANSWER
Answered 2022-Feb-15 at 18:46Here is a modified version of your code, with a test case, that addresses the issue(s) in your question.
Assumptions:
- The graph is directed, with edges as per
adj_list
; - The graph may have cycles (hence the desire to track a prior encounter using
visited
); - We want to traverse the graph using DFS.
Key logic:
- Append
start
node tostack
withwaiting_for_adj_list
flag set to False - In the DFS loop, pop a node from
stack
and either (1) mark it as visited, re-append it tostack
withwaiting_for_adj_list
flag set to True and append its children tostack
(subject to detection of a cycle or a broken budget) or (2) reset visited status for the node and its children. - Exit early upon reaching
end
node at or under budget.
Note that I have taken some liberties in type usage (list
instead of deque
for stack
, dict
instead of list
for parent
and visited
, maybe a couple of others) to avoid complexity and/or complications outside the focus of your question.
QUESTION
I have a type Builder
with a Generic Associated Type (GAT) InstanceForBuilder<'a>
.
I'd like to write a function (build_with_42_for_bool
) that constraints the Builder
to only those cases where Builder::InstanceForBuilder<'a>::InstanceProperty == bool
(for all 'a
).
I've been playing around for a while to get the syntax around this for <'a>
right, but haven't been able to make this work.
The lifetime can't be a template argument of the function itself, because the reference only lives inside it.
Is this possible at all yet, given that GAT is an unstable feature?
...ANSWER
Answered 2021-Dec-30 at 19:33The correct syntax to do what you want is:
QUESTION
I am struggling to implement a-Star algorithm on Bloxorz game. Which the goal is reach the end using 1 x 1 x 2 block. I implement the algorithm but it is inconsistent. Sometimes it doesn't give the shortest solution. For example:
...ANSWER
Answered 2021-Dec-12 at 12:45Assuming everything else in your implementation is correct, it's just because your heuristic is not admissible.
Consider the maze:
QUESTION
I'm using OrientDB to represent large city maps and calculate the shortest traversal times between a pair of nodes when the need arises. I have the following method:
...ANSWER
Answered 2021-Dec-07 at 23:33Turns out the error had nothing to do with the bracket itself. Passing the "direction='OUT'"
and "customHeuristicFormula='EUCLIDEAN'"
parameters in as part of the string was the problem. The below block did the trick.
QUESTION
I want to change the text of a child function component when I hover over a button of my parent class component. I'm having trouble accessing the prop though in the child component and getting null. Any help is appreciated
parent component:
...ANSWER
Answered 2021-Nov-19 at 05:03As @Rajesh has mentioned in a comment, you are passing props to your AlgoExplaination
(sic) component incorrectly like this:
QUESTION
I want to save all of the data in a json file. how can i parse my data using meta? I don't know my meta format is ok or not. finally yield the all of the data (which i through by meta and which i parse_v) in a json file help me to out this problem, please.
now i add full code. hope so you find out my problem
...ANSWER
Answered 2021-Jul-05 at 08:10Here is the answer according to your question:
If you want to transfer data from one parse methon to another using meta, you need to create key for each value and injected each key-value pair in Request using meta ,after all, in parse_v method, you have to create key newly and to grab previous key using response.meta and it's the new key-value pairs to yield data like 'Category': response.meta['cat']
QUESTION
I'm working on a 2D game in Unity and am using the A* Pathfinding Package from Aron Granberg.
Everything appears to be working fine. AIPaths are being generated and AI Agents are navigating from point to point and avoiding obstacles as expected. It's fine except for one thing.
The position.z
of the AI Agent is incorrect.
The spawn origin of the AI Agent has a z of 0, and the target point has a z of 0, yet the AI Agent's z fluctuates between -9 and -1 as it traverses the path. The path itself appears to have a z position of 0 at each waypoint.
I haven't modified the code in the package at all and just followed the documentation when setting it up for 2D.
Any ideas what could be causing this?
NOTE: I haven't included a screenshot of it, but the prefab that is being spawned in as the AI Agent has a transform position of (0,0,0).
The A-star pathfinder object:
The AI Agent object (note that the Z pos is not 0):
The spawn point object that sets the spawn for the AI agent:
The destination target object that the AI Agent is heading to:
...ANSWER
Answered 2021-Jun-14 at 02:09In case anyone else runs into this problem.
The fix was to add a Rigidbody2D to my AI Agent and set the gravity scale to 0.
Even though my game doesn't use Unity's physics system for movement and the Astar package can move AI agents by transform, for some reason it requires a Rigidbody to keep the Z position at 0.
I'm still not really sure why this solves the problem because, when I was debugging the third-party Astar code, it always returned nextPosition values with a Z position of 0 yet the actual position that the AI Agent was updated to had varying Z positions...
If you have more info, leave a comment and I'll add it to the answer.
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