I want to execute Astar algorithm for path finding in the below code.Can someone please correct my code with .There seems to be a looping error.

function P = Astar3D(Env,start,goal)

% Initialize the open and closed lists

openList = containers.Map('KeyType','double','ValueType','str')

closedList = containers.Map('KeyType','double','ValueType','str')

% Add the starting node to the open list with a cost of 0

% Convert start node to scalar key

startKey = num2str(start)

% Add the starting node to the open list with a cost of 0

openlist('startKey')= 0;

% Loop until the open list is empty

while ~isempty(openList)

% Find the node with the lowest f cost

[fValues, fKeys] = sort(values(openList));

currentKey = keys(openList);

current = currentKey{fKeys(1)};

minF = fValues(1);

% Check if the current node is the goal node

if current == goal

P = closedList;

return

end

% Remove the current node from the open list and add it to the closed list

openList.remove(current);

closedList(current) = minF;

% Find the neighbors of the current node

neighbors = find_neighbors(current,Env);

% Loop through each neighbor

for i = 1:length(neighbors)

neighbor = neighbors(i);

% Calculate the g, h, and f costs for the neighbor

gCost = closedList(current) + distance(current,neighbor);

hCost = distance(neighbor,goal);

fCost = gCost + hCost;

% If the neighbor is already on the closed list and the new f cost is higher, skip it

if closedList.isKey(neighbor) && closedList(neighbor) <= fCost

continue

end

% If the neighbor is already on the open list and the new f cost is higher, skip it

if openList.isKey(neighbor) && openList(neighbor) <= fCost

continue

end

% Add the neighbor to the open list

openList(neighbor) = fCost;

end

end

% If the open list is empty and the goal node has not been found, return an empty path

P = [];

end

% Helper function to find the neighbors of a node in the 3D environment

function neighbors = find_neighbors(node,Env)

% Initialize an empty list for the neighbors

neighbors = [];

% Loop through all possible adjacent nodes

for dx = -1:1

for dy = -1:1

for dz = -1:1

% Skip the current node

if dx == 0 && dy == 0 && dz == 0

continue

end

% Calculate the coordinates of the adjacent node

x = node(1) + dx;

y = node(2) + dy;

z = node(3) + dz;

% Check if the adjacent node is within the bounds of the environment

if x < 1 || x > size(Env,1) || y < 1 || y > size(Env,2) || z < 1 || z > size(Env,3)

continue

end

% Check if the adjacent node is blocked

if Env(x,y,z) == 1

continue

end

% Add the adjacent node to the list of neighbors

neighbors(end+1,:) = [x y z];

end

end

end

end

% Helper function to calculate the Euclidean distance between two nodes

function d = distance(node1,node2)

d = sqrt(sum((node1-node2).^2));

end

Error:

startKey = num2str(start)

% Add the starting node to the open list with a cost of 0

openlist('startKey')= 0;

% Loop until the open list is empty

while ~isempty(openList)

% Find the node with the lowest f cost

[fValues, fKeys] = sort(values(openList));

currentKey = keys(openList);

current = currentKey{fKeys(1)};

minF = fValues(1);

Error: File: untitled.m Line: 46 Column: 7

Invalid text character. Check for unsupported symbol, invisible character, or pasting of non-ASCII characters.

[Walter Roberson]

Please attach your untitled.m file so that we can examine the exact content.

[ALIASGAR]

i have attathed it.The Astar_3D.m file is the same as untitled.m file

Answer 1

[Walter Roberson]

The file you attached contains

openlist(1,1) startKey

Notice you forgot the "=" in the assignment.

You have a number of problems with the way you use the containers.Map.

• there is no ValueType of 'str'
• ValueType of 'string' is not supported
• You do not even try to assign a string() object -- you assign character vector
• You also assign numeric 0 -- so you would need to use ValueType 'any'
• You try to use two subscripts on the container, but only a single subscript is supported
• You later use only a single subscript for the container
• You try to assign to openlist and closedlist but the containers are named openList and closedList