Hi ...how to generate transition probability matrix using markov property for acceleration and velocity ?

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Harini pushparaj
Harini pushparaj 2017-12-29
评论： Harini pushparaj 2018-1-4
I want to generate a transition probability matrix for acceleration and velocity ,but the problem is I don't have data for acceleration and velocity so I want to use rand command to generate a random values.I already found a code for acceleration and velocity data but in this code they have loaded a data and from that data they generate the TPM matrix .But in my case I want to use a rand command for accel and velocity in order build the TPM matrix .How can I do it?Thank you.
function transMat = mwExample
load('Sample data set mathworks.mat')
%%First bin data into categories
speedBinN = 5;
aceelBinN = 5;
speed = binit( data(:,2), linspace(min(data(:,2)),max(data(:,2)),speedBinN) ); % bin them into categories
accel = binit( data(:,3), linspace(min(data(:,3)),max(data(:,3)),aceelBinN) );
%%count up transitions
transCountMat = zeros(speedBinN,aceelBinN,speedBinN,aceelBinN);
for ii = 1:size(data,1)-1
transCountMat( speed(ii),accel(ii),speed(ii+1),accel(ii+1) ) = transCountMat( speed(ii),accel(ii),speed(ii+1),accel(ii+1) ) + 1;
end
%%calculate probabilities
sumOverPossibleDestinations = sum( sum(transCountMat, 4), 3);
transMat = bsxfun( @rdivide, transCountMat, sumOverPossibleDestinations )

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回答（1 个）

Sarah Mohamed
Sarah Mohamed 2018-1-3
Assuming 'data' contains the speed and acceleration loaded from the sample file, you can build a matrix of uniformly distributed random numbers using the 'rand' function.
It looks like 'data' is just a 2D matrix. If column 2 of 'data' contains the speed and column 3 contains the acceleration, you could create a random 2D matrix with three columns via:
data = rand(100, 3);
For more on this function, you may refer to the documentation link below:
http://www.mathworks.com/help/matlab/ref/rand.html
  2 个评论
Harini pushparaj
Harini pushparaj 2018-1-4
@ Sarah Mohamed ...Thank you so much for the reply..I tried that way initally but it showed me error saying
Index exceeds matrix dimensions.
Error in markov (line 9)
transCountMat( speed(ii),accel(ii),speed(ii+1),accel(ii+1) ) = transCountMat(
speed(ii),accel(ii),speed(ii+1),accel(ii+1) ) + 1;
Harini pushparaj
Harini pushparaj 2018-1-4
This was my code ..what should I modify to attain the probability matrix
data = rand(100, 3)
speedBinN = 5;
aceelBinN = 5;
speed = histc( data(:,2), linspace(min(data(:,2)),max(data(:,2)),speedBinN) ); % bin them into categories
accel = histc( data(:,3), linspace(min(data(:,3)),max(data(:,3)),aceelBinN) );
%%count up transitions
transCountMat = zeros(speedBinN,aceelBinN,speedBinN,aceelBinN);
for ii = 1:size(data,1)-1
transCountMat( speed(ii),accel(ii),speed(ii+1),accel(ii+1) ) = transCountMat( speed(ii),accel(ii),speed(ii+1),accel(ii+1) ) + 1;
end
%%calculate probabilities
sumOverPossibleDestinations = sum( sum(transCountMat, 4), 3);
transMat = bsxfun( @rdivide, transCountMat, sumOverPossibleDestinations )

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