how can i count the values above a threshold of random data and represent on a graph of time vs. rate ?

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Ana-Patricia Lopez 2013-11-17

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评论： Ana-Patricia Lopez 2014-1-7

the # of occurrences (Rate) should be represented right in the middle of time slot. say 6 values above threshold within 0-1 second. 6 should be at .5s in the graph.

any help is appreciated thanks.

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Ana-Patricia Lopez 2014-1-7

编辑：Ana-Patricia Lopez 2014-1-7

I might be missing something. The plot with the graph showing the values above threshold does not seem to match the plot with the counts. I would like to match the bin ranges just so that I could use the second plot to know how many values fall within a certain amount of time. So, pretty much, match the x-range (bin range) that represents time in the first plot, to the x-range (bin range) from the second plot. As you can see, the second plot shows markers where there are not even numbers above the threshold (which is .5)... Any help is appreciated. thanks.

This is what I have so far:

close all

clear all

clc

THRESHOLD=0.5;

%t = 0:pi/100:6*pi;

t=0:pi/100:7;

y=sin(t);

P=[t' y'];

y_values=P(:,2);

Y=y_values>THRESHOLD;

Q=P(Y,:);

figure(1)

hold on

plot(P(:,1),P(:,2))

plot(Q(:,1),Q(:,2),'.r')

xlabel('time')

x=t;

binranges=(0:1:7);

BR= (binranges');

[bincounts, ind]=histc(x,binranges);

ind(:)=(ind');

counts=accumarray(ind(:), y(:) >=THRESHOLD);

figure

bar(BR,bincounts,'histc')

%plot(BR,bincounts,'+r');

plot((BR(1:end-1)+BR(2:end))/2, bincounts(1:end-1),'+r')

set(gca,'XTick',1:length(t));

set(gca,'YLim',[0, 40])

xlabel('bin ranges')

ylabel('Counts')

Ana-Patricia Lopez 2014-1-7

i will post a new question for a new answer since this question was already answered with what I needed. unless you prefer to answer this question here, that is fine with me.

Ana-Patricia Lopez 2014-1-7

http://www.mathworks.com/matlabcentral/answers/111606-on-a-histc-plot-the-marker-specifiers-do-not-show-the-data-i-wanted-from-the-previous-plot-how-c

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Walter Roberson 2013-11-18

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Apply histc() with evenly-distributed bins (of the desired time interval), applying it to your times. Use the two-output form of histc(), and then the second output will tell you the bin number. At that point,

counts = accumarray(bin_number(:), y(:) >= THRESHOLD);

This will give you the number of occurrences for each bin.

After that it just becomes a matter of text()'ing the counts into place at the mid-point of each interval.