DTW is implemented in both Matlab and C/MEX. The C/MEX function is very fast. The algorithm we use is the standard one from wiki: http://en.wikipedia.org/wiki/Dynamic_time_warping
There is a demo in the package. To use, just call:
d=dtw(s,t,w) or d=dtw_c(s,t,w)
Quan Wang (2021). Dynamic Time Warping (DTW) (https://www.mathworks.com/matlabcentral/fileexchange/43156-dynamic-time-warping-dtw), MATLAB Central File Exchange. Retrieved .
The function does not work for vectors of different length
Something is wrong...
should be 12
dtw_wiki = dtw(s2',s1',10)
plot(s1,'DisplayName','s1');hold on;plot(s2,'DisplayName','s2');grid;hold off;
Hi Quan, thanks for your contribution. I have a request which I am not sure it is proper. Do you mind adding the warping path to the output? It could be appreciated a lot if you could. But if it takes lots of effort, never mind. Thanks for your contribution.
Works well. Thank you very much. Especially the C/MEX one is very fast.
x = -10:0.1:10;
y = sin(x);
len = length(y);
y2 = interp1(1:len,y,linspace(1,len,2*len));
I'm very new to dynamic time warping. Does "D" indicate the similarity between two vectors?
What is a common value for the w parameter?
Just wonder, which is the corresponding paper for this code?
It is nice. It would be useful if you can add an option to force the alighment of start/end points of two signals. Or force the alignment of selected points (so it becomes interpolation in a sense).
Hi Quan, This is a great piece of work and I have made slight changes to normalize the DTW distance by its warping path for both matlab and c versions for my project. Please let me know if I can contribute that here.
Could i ask you a question? The code works perfectly when two input data have the same length. But if two input data have different length, such as [10 12 14 18 14 12 10 10 12 14 18 14 12 10] and [NaN 12 14 18 14 12 10 10 12 14 18 NaN NaN NaN], the output is NaN. Could you think how to deal with it?
Hi Quan Wang.
I have a question:
What the paper does algorithm DTW using adapt window size belong to ?
I am getting error as
'Maximum variable size allowed by the program is exceeded.'
for below line.
D=zeros(ns+1,nt+1)+Inf; % cache matrix
The window parameter w in function dtw(s,t,w) is the parameter that prevents big gradients.
Could I ask you a question? I just want to confirm with you, so that I correctly understand what is written in your file. You didn't implement the slope constraint (the one that prevents too much or too little gradient, namely the fifth condition in Sakoe & Chiba 1978), did you?
Sakoe & Chiba 1978: Dynamic programming algorithm optimization for spoken word recognition.
You need to learn what is a MATLAB function first.
What does MATLAB Compiler do? When I try to run the code, I get an error message for Line 1 (function d=dtw(a,b,w)).
Hi Steven du,
Yes, you are right. I forgot to update it when I extended it for multi-dimensional signals.
I thinks line 19 of dtw.m
Ought to be ns=size(s,1)
Hi Leonel Rozo, it now supports multidimensional signals.
Does it consider multidimensional signals?
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