Error: Index exceeds matrix dimensions

I'm getting the following error in my code. Could this be due to the fact that my filename is rft instead of txt?

>> RRTpathplan
Index exceeds matrix dimensions.

Error in RRTpathplan (line 8)
object_coord = rawdata(1:500,2);

My Code:

function prm = path_planner
% Import Obstacle Locations
filename ='Simple2Obst.rtf';
delimiterIn = ' ';
headerlinesIn = 0;
rawdata = importdata(filename,delimiterIn,headerlinesIn);
object_coord = rawdata(1:500,2);
% Draw Course
map = figure;
course_outx=[-2,-4,-6,-6, 6,6,4,2];
course_outy=[ 0, 0, 0,12,12,0,0,0];
hold on;
plot(course_outx,course_outy,'k','LineWidth',5);
axis([-7,7,-6,13]);
axis equal
set(gca,'XTick',-13:1:13)
set(gca,'YTick',-6:1:13)
grid ON
obst.ball = {};
% Tile the obstacles with balls
count = 1;
for i=1:2:500
  if (object_coord(i,1)<999)
      onew.p = [object_coord(i,1);object_coord(i+1,1)];
      onew.r = 1/3;
      onew.handle = [];
      obst.ball{end+1} = onew;
      circle(onew.p(1,1),onew.p(2,1),onew.r,'b');
  end
end

% Set Start and Goal locations
p_start = [0;11];
p_goal = [0;-1];

rob.ballradius = 0.5;
rob.p = p_start;

% Parameters
param.res = 0.5;
param.thresh = 5;
param.maxiters = 1000;
param.smoothiters = 150;

circle(rob.p(1,1),rob.p(2,1),rob.ballradius,'g');
circle(p_goal(1,1),p_goal(2,1),rob.ballradius,'r');

% Plan the path
P = PlanPathRRT(rob,obst,param,p_start,p_goal);
% Plot the unsmoothed path
for i=2:length(P)
  plot([P(1,i);P(1,i-1)],[P(2,i);P(2,i-1)],'r','LineWidth',3);
end
% Smooth the path
if (~isempty(P))
  P = SmoothPath(rob,obst,param,P)
end
% Plot the smoothed path
for i=2:length(P)
  plot([P(1,i);P(1,i-1)],[P(2,i);P(2,i-1)],'g','LineWidth',3);
end

function h = circle(x,y,r,color)
hold on
th = 0:pi/50:2*pi;
xunit = r * cos(th) + x;
yunit = r * sin(th) + y;
h = plot(xunit, yunit,color,'LineWidth',3);
%hold off

function rrt = AddNode(rrt,p,iPrev)
node.p = p;
node.iPrev = iPrev;
rrt{end+1} = node;

function P = PlanPathRRT(rob,obst,param,p_start,p_goal)
global iterations
P = [];
rrt = {};
rrt = AddNode(rrt,p_start,0);
iter = 1;
while iter <= param.maxiters
  if mod(iter,50) == 0
      blah=0;
  end
  p = rand(2,1); % random p
%     p(1,1) = floor(p(1,1)*11-5);
%     p(2,1) = floor(p(2,1)*16-4);
  p(1,1) = p(1,1)*10-5;
  p(2,1) = p(2,1)*15-4;
  rob.p = p;
  col = InCollision_Node(rob,obst);
  if col == 1 % skip to next iteration
%         circle(p(1,1),p(2,1),0.1,'r');
      iter = iter + 1;
      continue
  end
  % do something if valid coordinate
  for i=1:length(rrt)
      dist = norm(rrt{i}.p - p);
      if (i==1) || (dist < mindist)
          mindist = dist;
          imin = i;
          l = rrt{i}.p;
      end
  end
  col = InCollision_Edge(rob,obst,p,l,param.res); %check for valid edge
  if col == 1 % skip to next iteration if not valid edge
%         circle(p(1,1),p(2,1),0.1,'r');
      iter = iter + 1;
      continue 
  end
  rrt = AddNode(rrt,p,imin); % add p to T with parent l
  dist = norm(p-p_goal);
  %display(iter,dist,length(rrt))
  fprintf('Nodes:   %d, Distance: %.1f, Iterations: %d/1000\n',length(rrt),dist,iter)
%     circle(p(1,1),p(2,1),rob.ballradius,'b');
%     circle(p(1,1),p(2,1),0.1,'b');
  plot([p(1,1);rrt{imin}.p(1,1)],[p(2,1);rrt{imin}.p(2,1)],'m','LineWidth',3);
  if (dist < param.thresh)
      col = InCollision_Edge(rob,obst,p,p_goal,param.res); %check for valid edge
      if col == 1 % skip to next iteration if not valid edge
          iter = iter + 1;
          continue 
      end
      iterations = iter
      % add qgoal to T with parent q and exit with success
      rrt = AddNode(rrt,p_goal,length(rrt));
      % construct Q here:
      i = length(rrt);
      P(:,1) = rrt{i}.p;
      while 1
          i = rrt{i}.iPrev;
          if i == 0
              return
          end
          P = [rrt{i}.p P];
      end
  end
  iter = iter + 1;
end
iterations = iter - 1

function col = InCollision_Node(rob,obst)
global checkcount;
checkcount = checkcount + 1;
col = 0;
numobst = length(obst.ball);
  for j=1:numobst % check for robot-obstacle collision
      % calculate distance between ith robot ball center and jth obstacle
      % ball center
      %dist = sqrt((rob.ball{i}.p(1)-obst.ball{j}.p(1))^2+(rob.ball{i}.p(2)-obst.ball{j}.p(2))^2+(rob.ball{i}.p(3)-obst.ball{j}.p(3))^2);
      dist = norm(rob.p-obst.ball{j}.p);
      if dist < (rob.ballradius + obst.ball{j}.r)
          col = 1;
          return;
      end 
  end
%end

function col = InCollision_Edge(rob,obst,p1,p2,res)
col = 0;
d = norm(p1 - p2);
m = ceil(d/res);
t = linspace(0,1,m);
for i=2:(m-1)
  p = (1-t(i))*p1 + t(i)*p2; %calculate configuration
  rob.p = p;
  col = InCollision_Node(rob,obst); 
  if col == 1
      return;
  end
end

function P = SmoothPath(rob,obst,param,P) %was SmoothPath(rob,obst,param,m,Q)
%
% INPUTS
%
%   rob - says where the robot is
%
%           NOTE: to make "rob" describe the robot at configuration
%           "something" (a column vector of length rob.n), you must call:
%
%             rob.q = something
%             rob = ForwardKinematics(rob);
%
%   obst - says where the obstacles are
%
%   param - some parameters:
%
%    param.res - resolution with which to sample straight-line paths
%    param.maxiters - maximum number of RRT iterations
%    param.thresh - distance below which a configuration is considered
%                   "close" to qgoal (called "d" in the homework)
%    param.smoothiters - maximum number of smoothing iterations
%
%   qstart, qgoal - start and goal configurations
%
% OUTPUTS
%
%   Q - a path, same format as before:
%       
%           Q = [q1 q2 q3 ... qM]
%
%               where q1=qstart and qM=qgoal; in other words, the sequence
%               of straight-line paths from q1 to q2, q2 to q3, etc., takes
%               the robot from start to goal without collision
%
% YOUR CODE HERE...
%
P = P;
[n,m] = size(P);
clearvars n;
l = zeros(m,1);
for k=2:m
  l(k)=norm(P(:,k)-P(:,k-1)) + l(k-1); % find all of the straight-line distances
end
l_init = l(m);
iter = 1;
while iter <= param.smoothiters
  s1 = rand(1,1)*l(m); 
  s2 = rand(1,1)*l(m); 
  if s2 < s1
      temps = s1;
      s1 = s2;
      s2 = temps;
  end
  for k=2:m
      if s1 < l(k)
          i = k - 1;
          break;
      end
  end
  for k=(i+1):m
      if s2 < l(k)
          j = k - 1;
          break;
      end
  end
  if (j <= i)
      iter = iter + 1;
      continue;
  end
  t1 = (s1 - l(i))/(l(i+1)-l(i));
  gamma1 = (1 - t1)*P(:,i) + t1*P(:,i+1);
  t2 = (s2 - l(j))/(l(j+1)-l(j));
  gamma2 = (1 - t2)*P(:,j) + t2*P(:,j+1);
  col = InCollision_Edge(rob,obst,gamma1,gamma2,param.res); %check for valid edge
  if col == 1
      iter = iter + 1;
      continue;
  end
  newP = [P(:,1:i) gamma1 gamma2 P(:,j+1:m)];
  clearvars P;
  P = newP;
  [n,m] = size(P);
  clearvars n;
  l = zeros(m,1);
  for k=2:m
      l(k)=norm(P(:,k)-P(:,k-1)) + l(k-1);
  end
  iter = iter + 1;
end

[dpb]

200 lines of code, none of which contains the offending line...

The error is that "Index exceeds matrix dimensions." in

object_coord = rawdata(1:500,2);

that has dimensions hardcoded. Whatever size(rawdata) returns, it's less than [1500,2]. We have no way to know why; perhaps whatever the way of getting the input failed and it's actually []. Your mission, should you choose to accept, is to track that down...

[D Penny]

Thanks for responding. Maybe this will provide some insight. The code I was attempting to run was from the website... http://coecsl.ece.illinois.edu/ge423/spring13/RickRekoskeAvoid/rrt.html

I simply downloaded both files (RRTpathplan.m and Simple2obst.txt) at the bottom of the page, added them to the same directory, and ran the RRTpathplan.m script. The only change that I made was I saved the txt file as a rtf (I have a Mac) and also changed that part of my code from...

filename ='Simple2Obst.txt';

to

filename ='Simple2Obst.rtf';

My question is, could that change be the reason why the code doesn't run?

[dpb]

Well, if you saved an input plain ASCII text file as RTF, then it's quite likely the attempt to read that file failed, yes.

But, the filename alone has no bearing on the content.

The question still is, what happens when try to actually read the file? Use the debugger and step through and see if it worked or not. Again, we can't see your system and do such simple sanity checks for you...

Answer 1

[Elias Gule]

Ok I downloaded the code and the text file from the website you mentioned. When running the code the rawdata variables has a size of 1 x 1000 (1 rows and 1000 columns); that is why this line of code

object_coord = rawdata(1:500,2);

gives an error,which basically asks for the first 500 rows from a vector that contains only one row. Now we can solve this by changing the rawdata to a matrix of 500 rows and 2 columns by adding this:

rawdata = reshape(rawdata,[],2);

after the line that initializes the rawdata variable. i.e between the line

rawdata = importdata(filename,delimiterIn,headerlinesIn);

and the line

object_coord = rawdata(1:500,2);

The code should work now.

[Amit Kabra]

I have got the same errors, when i added that code of lines, code works fine except that the obstacles are gone It should actually appear as in the link http://coecsl.ece.illinois.edu/ge423/spring13/RickRekoskeAvoid/rrt.html but obstacles are missing. Please Help

Answer 2

[cristian quiroga]

Hola. Use el mismo código y el problema se debe a que en el archivo de texto hay código HTML tanto en la cabecera como al final del .txt. Debes borrarlas y luego correr el código. Veras que funciona. Saludos.