Ugly Lines in Plot
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I am plotting joint angles while walking (multiple steps). I have two vectors, joint angle and percent of step. When I plot:
plot(percent,angle)
MATLAB plots my data but I have ugly horizontal lines across my plot connecting adjacent steps.
In the past I would separate steps with NaN's... but there has to be a easier way... What is the simplest way to get rid of these lines? Thanks ~Dan
1 Comment
Accepted Answer
Image Analyst
on 13 Jul 2012
Edited: Image Analyst
on 13 Jul 2012
If you want to find out where the backtracking happens, you can use diff(). Then just extract out the sections of the curve in-between the backtrack locations into separate arrays and plot them. If you want a demo, here's one:
% Generate some sample data.
index = 1;
for p = 1 : 15
oneX = 1:100;
x(index:index+99) = oneX;
sigma = 20 * rand(1);
r = oneX .* exp(-(oneX.^2)/(2*sigma^2))/sigma^2 + rand(1);
rayleigh(index:index+99) = r;
plot(x, rayleigh, 'r-', 'LineWidth', 2);
hold on;
grid on;
index = index + 100;
end
ylim([-.2 1]);
title('Plot with back tracking', 'FontSize', 20);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
%===============================================
% Now we have some sample data and we can begin.
%===============================================
% Find out where x reverses direction
dx = diff(x);
startingXs = find(dx<0)+1;
% Add the first element.
startingXs = [1 startingXs];
% Now we have our starting x's.
% Let's plot the curves one at a time.
figure;
for p = 1 : length(startingXs)
oneCurveX = x(startingXs(p):startingXs(p)+99);
oneCurveY = rayleigh(startingXs(p):startingXs(p)+99);
plot(oneCurveX, oneCurveY, 'b-', 'LineWidth', 2);
hold on;
grid on;
end
ylim([-.2 1]);
title('Plot without back tracking', 'FontSize', 20);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
2 Comments
Image Analyst
on 14 Jul 2012
Without generating the sample data and without all the comments and other fluff, essentially it's only about 7 or 8 lines of code.
More Answers (1)
Amarpal
on 12 Jul 2012
Perhaps you are talking about the gridlines? You can use the following: h = plot(percent,angle); set(h,'edgecolor','none')
Hope this is what you were looking for?
2 Comments
Andrea
on 12 Jul 2012
probably you should plot them as different function. One more thing that came to my mind is using plot(x,y,'.'). In this way you can get ride of lines at all.
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