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code running for infinite while plotting my array for correlation
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Hi,
I have problem as my code running for infinite time while I am plotting my arrays to achive coeffcient correlation.
here is my code:
for i=1:length(A)-300
Rx{i}= corrcoef(A (i:i+300), S(i:i+300));
Time_Rx=i;
B{1,i} = Rx(i)
C{1,i} = Time_Rx
end
(Aiming for plot Rx as a function over time)
plotting by using:
plot(B,C);
Can not figure out what is wrong, Any help would be appriciable.
20 Comments
Walter Roberson
on 24 Mar 2019
Edited: Walter Roberson
on 24 Mar 2019
I see no evidence that it is running for infinite time. It is, though, doing a sliding window of correlation coefficients, sliding one further each time, and that operation could take some time. Are you sure that you want to slide only one each time?
Note that you are writing into cell arrays, but it is not permitted to plot() a cell array. Especially since it is a cell of cells -- you write into Rx{i} but you B{1,i} = Rx(i) and notice that Rx(i) is a 1 x 1 cell, not the result of the correlation coefficient but rather the cell wrapping the result of the correlation coefficient.
Bob
on 24 Mar 2019
Edited: Bob
on 5 Apr 2019
Thanks walter,
Attached snip from command window is the evidence for infinite run. it has been running since last more than an hour. I am not sure if I want only slide one each time. (How it should be implimented in either case).
If it is not permitted to plot() a cell array, what to do to achive my plot in this case?
B{1,i} = Rx(i)
C{1,i} = Rx
One small mistake it was
Rx{i}= corrcoef(A (i:i+300), S(i:i+300));
instead of
Rx{i}= corrcoef(A (i:i+300), B(i:i+300));
Kindly recommend some path for the plotting.
Walter Roberson
on 24 Mar 2019
L = length(A) - 300;
B = zeros(2,2,L);
for K = 1 : L
B(:,:,K) = corrcoef(A(i:i+300), S(i:i+300));
end
C = 1 : L;
But it is not clear what you mean by plotting C (the index) vs B (a 2 x 2 array for each location).
It might make some sense to use
L = length(A) - 300;
B = zeros(L, 4);
for K = 1 : L
cc = corrcoef(A(i:i+300), S(i:i+300));
B(K, :) = cc(:);
end
C = 1 : L;
plot(C, B)
legend({'(1,1)', '(2,1)', '(1,2)', '(2,2)'})
Bob
on 5 Apr 2019
Dear Walter,
There must be some confusion, I wanted to plot CC as correlation cofficent between the values A and S, over time.
Still its not achived.
Walter Roberson
on 5 Apr 2019
When you calculate correlation coefficient between two columns, then the result is always 2 x 2.
Perhaps,
L = length(A) - 300;
B = zeros(L, 1);
for K = 1 : L
cc = corrcoef(A(i:i+300), S(i:i+300))
B(K) = cc(2,1);
end
plot(B);
Bob
on 6 Apr 2019
Hi Again Walter,
When I use your inputs, following errors appeared:
Command window:
Warning: Colon operands must be real scalars.
Array indices must be positive integers or logical values.
cc = corrcoef(A(i:i+300), S(i:i+300))
Walter Roberson
on 6 Apr 2019
L = length(A) - 300;
B = zeros(L, 1);
for i = 1 : L
cc = corrcoef(A(i:i+300), S(i:i+300))
B(i) = cc(2,1);
end
plot(B);
Bob
on 6 Apr 2019
Wow. It worked well.
How can I make a Linear plot of CC values to visualize the all correlation points, either negative or positive correlation?
Walter Roberson
on 6 Apr 2019
cc(1,1) is correlation of the section of A relative to itself. cc(2,2) is the correlation of the section of S relative to itself. cc(1,2) and cc(2,1) are the correlation of each relative to the other.
... I'm not sure what you are asking to extract and plot?
Bob
on 6 Apr 2019
Edited: Bob
on 6 Apr 2019
What I mean is, can I see eaither cc(1,2) or cc(2,1), as a linear correlation plot by using all the correlation data point from cc ?? some thing like attached figure (as example).
Also if I can plot one more figure
for Z : diffrence between A and S.
Z=A-S;
figure(2)
plot(B,Z);
or
plot(cc,Z);
Is it possible ? I tried and error appears in command window:
Error using plot
Vectors must be the same length.
Walter Roberson
on 8 Apr 2019
p = polyfit(B,1);
hold on
t = 1 : length(A)-300;
plot(t, polyval(p, t), 'b-');
Bob
on 8 Apr 2019
It shows error:
Error using polyfit (line 44)
X and Y vectors must be the same size.
p = polyfit(B,1);
Walter Roberson
on 8 Apr 2019
t = 1 : length(A)-300;
p = polyfit(t, B, 1);
hold on
plot(t, polyval(p, t), 'b-');
hold off
Bob
on 8 Apr 2019
still have the error:
Error using polyfit (line 44)
X and Y vectors must be the same size.
p = polyfit(t, B, 1);
Bob
on 8 Apr 2019
strange plotting now, see attached Image.
If its not achivable its fine.
Can you help me plot another para meter in contineuation with same code:
A = randn(1e3,1);
S = randn(1e3,1);
L = length(A) - 300;
B = NaN(length(A), 1);
for i = 1 : L
cc = corrcoef(A(i:i+300), S(i:i+300));
B(i) = cc(2,1);
end
plot(B);
Z=A-S;
figure(2)
plot(B,Z);
Can I plot B values at X axis and Z values at Y axis and in diffrent colors ?
Walter Roberson
on 8 Apr 2019
A (nearly) horizontal line looks plausible to me given that data. Area above looks like it mostly balances area below, and the decreasing variance towards the right side would tend to anchor the endpoint of the line in values close to that range.
Walter Roberson
on 8 Apr 2019
"Can I plot B values at X axis and Z values at Y axis and in diffrent colors ?"
When would the different colors be triggered?
Your B values increase and decrease irregularly like you see on the first plot. It would not seem to make sense to use them as the X axis values.
When you talk about "and in diffrent colors" my first interpretation was that you were wanting to plot two different lines, one for B, and one for Z, but then talking about plotting them on the X and Y axis would not seem to make any sense. The closest I can find to make sense of that would be to do something like
NA = length(A);
ZERO = zeros(NA, 1);
t = 1 : NA
plot3(t, B, ZERO, 'k', t, ZERO, Z, 'b');
which plots them with a common time base and with two different lines, each along a different axes.
Jan
on 11 Apr 2019
Worked well.
@Bob: Please use flags only to informa admins about inappropriate contents like rudeness or spam. Thanks.
Bob
on 12 Apr 2019
Hi Walter,
How can I avraged my data (A anS) in minutes (for 10 minutes) before I do correlation calculation, in above code ??
Accepted Answer
BERGHOUT Tarek
on 6 Apr 2019
Edited: BERGHOUT Tarek
on 6 Apr 2019
if you want to plot Rx , then you should plot B not C, and you can't plot B vs C in this example because C and B they dont have the same length ( dimensions are not the same), try this code , I hope that it is helpful:
clear all;
clc;
%%%
t=1:600;
A=0.25;
B=1.25;
f1=0.5;
f2=0.025;
S=A*sin(f1*t)+B*cos(f2*t)+wgn(size(t,1),size(t,2),3);
A=S+randn(size(S));
%%%
B=[];
for i=1:length(A)-300
Rx=corrcoef(A (i:i+300), S(i:i+300));
B=[B Rx];
end
plot(1:size(B,2),B);
1 Comment
Bob
on 6 Apr 2019
Dear berghout,
How can I make a Linear plot of Rx values to visualize the all correlation points, either negative or positive correlation?
More Answers (0)
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