Question 1 SOLVED
I am working on the following simulation:
x = [8 9 7 6 5];`
if isvector(x)
for i=1:length(x)
% simulation gives me a matrix y,t,z, (c by 5)
% where size(y,1)=size(z,1)=size(t,1)= lenght(x)=5
% size(y,2)=c
% a plot will collect all lines:
% for x=8 there are 3 lines ( the first row of each matrix `y`, `t`, `z`
% for x=9 there are 3 lines ( the second row of each matrix `y`, `t`, `z`
% ...
% for x=5 there are 3 lines ( the 5th row of each matrix `y`, `t`, `z`
end
end
Let me show an example:
y = rand(5,8)
t = rand(5,8)
z = rand(5,8)
To plot I have started with:
% I was using the initial loop:
if isvector(x)
for i=1:length(x)
% simulation gives me a matrix y,t,z, (c by 5)
%% plots
h(1)=figure;
plot (c,y(i,:));
grid on;
hold on;
plot (c,t(i,:));
plot (c,z(i,:));
hold off;
end
end
As a result, MATLAB gives me 3 figures, but I have expected only one figure with multiple lines. I start from the inside of the initial loop and create a new loop, but it doesn't help me. How to fix it? How to plot all lines (in this example, all 15 lines (#x(i) = 5, #array = 3))?
If you need that loop for further analysis, just move the figure() outside the loop. Otherwise, you could also plot all lines from a single plot() call:
x = [8 9 7 6 5];
c = 1:8;
y = rand(5, 8);
t = rand(5, 8);
z = rand(5, 8);
% Loop approach, move figure() outside the loop
if isvector(x)
figure(1);
hold on;
for i = 1:length(x)
plot(c, y(i, :));
plot(c, t(i, :));
plot(c, z(i, :));
end
hold off;
grid on;
end
% Plot everything with one plot() call
if isvector(x)
figure(2);
plot(c, [y; t; z]);
grid on;
end
The outputs are the same except for the lines' color, which is due to the order of the plotting (first line of y, t, z, second line of ..., and so on vs. all lines from y, all lines from t, and so on.
Hope that helps!
EDIT: To plot all three lines for each x(i) in separate figures, you could use this loop approach:
x = [8 9 7 6 5];
c = 1:8;
y = rand(5, 8);
t = rand(5, 8);
z = rand(5, 8);
if isvector(x)
for i = 1:length(x)
figure(i);
hold on;
plot(c, y(i, :));
plot(c, t(i, :));
plot(c, z(i, :));
hold off;
grid on;
end
end
Related
I want to plot some data, but I can't.
It is assumed that we have 820 rows in 2 columns, representing the x and y coordinates.
My code is as follows:
load('MyMatFileName.mat');
[m , n]=size(inputs);
s = zeros(m,2);
for m=1:820
if inputs(m,end-1)<2 & inputs(m,end)<2
x = inputs(m,end-1)
y = inputs(m,end)
plot(x,y,'r','LineWidth',1.5)
hold on
end
end
I've edited your code and added comments to explain the changes you could make, but see below I've also re-written your code to be more like how it should be done:
load('MyMatFileName.mat'); % It's assumed "inputs" is in here
% You don't use the second size output, so use a tilde ~
[m, ~] = size(inputs);
%s = zeros(m,2); % You never use s...
% Use a different variable for the loop, as m is already the size variable
% I've assumed you wanted ii=1:m rather than m=1:820
figure
hold on % Use hold on and hold off around all of your plotting
for ii=1:m
if inputs(m,end-1)<2 && inputs(m,end)<2 % Use double ampersand for individual comparison
x = inputs(m,end-1)
y = inputs(m,end)
% Include the dot . to specify you want a point, not a line!
plot(x, y, 'r.','LineWidth',1.5)
end
end
hold off
A better way of doing this whole operation in Matlab would be to vectorise your code:
load('MyMatFileName.mat');
[m, ~] = size(inputs);
x = inputs(inputs(:,end-1) < 2 & inputs(:,end) < 2, end-1);
y = inputs(inputs(:,end-1) < 2 & inputs(:,end) < 2, end);
plot(x, y, 'r.', 'linewidth', 1.5);
Note that this will plot points, if you want to plot the line, use
plot(x, y, 'r', 'linewidth', 1.5); % or plot(x, y, 'r-', 'linewidth', 1.5);
There is example of the web that shows how to do animated plot in a single figure.
However, I want to do two subplots in a single figure, such that they will show animation in a first subplot, and then the animation ina second subplot.
Using 'figure(1)' or 'figure (2)' and 'hold on', I can do the animation plot as follows. However, How do I call the subplot to do the similiar things?
So the effect I am looking for is: 1) figure that is opened and has two subplot. 2) plot the animated curve in the 1st subplot, then plot the animated curve in the 2nd subplot. 3) I want to go back to the 1st subplot to plot more things, and also go to 2nd subplot to plot more things.
figure(1); hold on; x = 1:1000;
y = x.^2;
%// Plot starts here
figure,hold on
%// Set x and y limits of the plot
xlim([min(x(:)) max(x(:))])
ylim([min(y(:)) max(y(:))])
%// Plot point by point
for k = 1:numel(x)
plot(x(k),y(k),'-') %// Choose your own marker here
%// MATLAB pauses for 0.001 sec before moving on to execue the next
%%// instruction and thus creating animation effect
pause(0.001);
end
Just do the subplot's in the loop:
for k = 1:numel(x)
subplot(1,2,1)
plot(x(k),y(k),'-') %// Choose your own marker here
subplot(1,2,2)
plot(x(1:k),y(1:k))
%// MATLAB pauses for 0.001 sec before moving on to execue the next
%%// instruction and thus creating animation effect
pause(0.001);
end
% Easiest way
x = rand(1, 11); y = rand(1, 11);
z = rand(1, 11); a = rand(1, 11);
figure
for i = 1 : 10
subplot(211)
plot(x(i : i+1), y(i : i+1), '.-k');
hold on; % include this if you want to show plot history
subplot(212)
plot(z(i : i+1), a(i : i+1), '.-k');
drawnow;
pause(0.1);
end
% If you don't want to call "plot" interatively
x = rand(1, 11); y = rand(1, 11);
z = rand(1, 11); a = rand(1, 11);
figure
subplot(211)
p1 = plot(NaN, NaN, 'marker', 'o');
subplot(212)
p2 = plot(NaN, NaN, 'marker', 'd');
for i = 1 : 10
set(p1, 'xdata', x(i : i+1), 'ydata', y(i : i+1));
set(p2, 'xdata', z(i : i+1), 'ydata', a(i : i+1));
drawnow;
pause(0.1);
end
First define your plot as a construct, so p1 = plot(x,y). Then you set up your loop and in the loop your write
set(p1,'YData',y);
This will update the plot p1s YData which is y. If you want to see it in an animated form just add a pause(0.1) %seconds after the set.
I'm trying to animate a plot for this equation see below I'm trying to animate it for b when 300>= b <= 486
clear all, clc,clf,tic
m=3.73;
a=480;
b=486;
r=1;
fs=44100;
x=linspace(0,2*pi,fs)';
y=m^3*cos(sqrt(a*r*x)).^(0.77)/r + m^3*cos(sqrt(b*r*x)).^(0.77)/r-20;
normalize_y=(y/max(abs(y))*0.8);
plot(x,y)
I'm using octave 3.8.1 which is a clone of matlab
Put your plotting code in a for loop with b as the iterating variable, then place a pause for a small amount of time. After, plot your graph, then use drawnow to refresh the plot. In other words, try this code. I've placed %// Change comments in your code where I have introduced new lines:
m=3.73;
a=480;
r=1;
fs=44100;
x=linspace(0,2*pi,fs)';
figure;
for b = 300 : 486 %// Change
y=m^3*cos(sqrt(a*r*x)).^(0.77)/r + m^3*cos(sqrt(b*r*x)).^(0.77)/r-20;
normalize_y=(y/max(abs(y))*0.8);
pause(0.1); %// Change
plot(x,y);
title(['b = ' num2str(b)]); %// Change
drawnow; %// Change
end
As a bonus, I've put what the current value of b is at each drawing of the plot. BTW, I don't know why normalize_y is in your code when you aren't using it. Do you mean to plot normalize_y instead of y? Just an after thought. Anyway, try that out and see how it looks. Good luck!
Another solution would be to use the handle of a plot and then only update the 'YData'-property of a plot. That is especially useful for more complex plots where there are more than 1 line but you only want to change one line. Also Axis-labels are not overwritten then, which generally prevents alot of overhead.
In Matlabcode it could look like this:
% // Parameter and x-range
m=3.73;
a=480;
r=1;
fs=44100;
x=linspace(0,2*pi,fs)';
% // function to compute y for given x and parameter b
f = #(x, b) m^3*cos(sqrt(a*r*x)).^(0.77)/r + m^3*cos(sqrt(b*r*x)).^(0.77)/r-20;
% // first plot out of loop (to get plot handle)
figure;
b = 300;
y = f(x, b);
handle = plot(x, y);
xlabel('x') % // only set once
ylabel('y=f(x,b)') % // only set once
title(['b = ' num2str(b)]);
pause(0.1);
% // animate for b = 301 to 86
for b = 301:486 %// Change
set(handle, 'YData', f(x, b)) % set new y-data in plot handle
pause(0.1); %// update plot
title(['b = ' num2str(b)]); %// update title
end
This will work with octave 3.8.1
% // Parameter and x-range
m=3.73;
a=480;
r=1;
fs=44100;
x=linspace(0,2*pi,fs)';
% // function to compute y for given x and parameter b
f = #(x, b) m^3*cos(sqrt(a*r*x)).^(0.77)/r + m^3*cos(sqrt(b*r*x)).^(0.77)/r-20;
% // first plot out of loop (to get plot handle)
figure;
b = 300;
y = f(x, b);
handle = plot(x, y);
xlabel('x') % // only set once
ylabel('y=f(x,b)') % // only set once
title(['b = ' num2str(b)]);
pause(0.1);
% // animate for b = 301 to 86
for b = 301:486 %// Change
%set(handle, 'YData', f(x, b)) % set new y-data in plot handle
%To work with octave 3.8.1 use the line below
set(handle, 'YData', real (f(x, b)))
pause(0.1); %// update plot
title(['b = ' num2str(b)]); %// update title
end
I'd like to draw a curve on an empty (semilog-y) graph by clicking the points I want it to run through, on the X-Y plane.
Is there a function for this?
edit: I'm trying to do this by obtaining the position of last pointer click -
axis([0 3000 0 1000]);
co=get(gcf, 'CurrentPoint');
It seems to return the cursor position at the time of execution, but it does not change later.
edit2: Here's what works for me. The actual drawing I can do by using the arrays of points collected.
clear
clc
h=plot(0);
grid on;
xlim([0 3000]);
ylim([0 1000]);
datacursormode on;
% Enlarge figure to full screen.
screenSize = get(0,'ScreenSize');
set(gcf, 'units','pixels','outerposition', screenSize);
hold on;
% Print the x,y coordinates - will be in plot coordinates
x=zeros(1,10); y=zeros(1,10);
for p=1:10;
[x(p),y(p)] = ginput(1) ;
% Mark where they clicked with a cross.
plot(x(p),y(p), 'r+', 'MarkerSize', 20, 'LineWidth', 3);
% Print coordinates on the plot.
label = sprintf('(%.1f, %.1f)', x(p), y(p));
text(x(p)+20, y(p), label);
end
Not really, but now there is:
function topLevel
%// parameters
xrange = [0 100];
yrange = [1e-4 1e4];
%// initialize figure, plot
figure, clf, hold on
plot(NaN, NaN);
axis([xrange yrange]);
set(gca, 'YScale', 'log')
t = text(sum(xrange)/2, sum(yrange)/2, ...
'<< Need at least 3 points >>',...
'HorizontalAlignment', 'center');
%// Main loop
xs = []; p = [];
ys = []; P = [];
while true
%// Get new user-input, and collect all of them in a list
[x,y] = ginput(1);
xs = [xs; x]; %#ok<AGROW>
ys = [ys; y]; %#ok<AGROW>
%// Plot the selected points
if ishandle(p)
delete(p); end
p = plot(xs, ys, 'rx');
axis([xrange yrange]);
%// Fit curve through user-injected points
if numel(xs) >= 3
if ishandle(t)
delete(t); end
%// Get parameters of best-fit in a least-squares sense
[A,B,C] = fitExponential(xs,ys);
%// Plot the new curve
xp = linspace(xrange(1), xrange(end), 100);
yp = A + B*exp(C*xp);
if ishandle(P)
delete(P); end
P = plot(xp,yp, 'b');
end
end
%// Fit a model of the form y = A + B·exp(C·x) to data [x,y]
function [A, B, C] = fitExponential(x,y)
options = optimset(...
'maxfunevals', inf);
A = fminsearch(#lsq, 0, options);
[~,B,C] = lsq(A);
function [val, B,C] = lsq(A)
params = [ones(size(x(:))) x(:)] \ log(abs(y-A));
B = exp(params(1));
C = params(2);
val = sum((y - A - B*exp(C*x)).^2);
end
end
end
Note that as always, fitting an exponential curve can be tricky; the square of the difference between model and data is exponentially much greater for higher data values than for lower data values, so there will be a strong bias to fit the higher values better than the lower ones.
I just assumed a simple model and used a simple solution, but this gives a biased curve which might not be "optimal" in the sense that you need it to be. Any decent solution really depends on what you want specifically, and I'll leave that up to you ^_^
I have a function:
A = [5,16,18,4,9;
9,10,14,3,18;
2,7,9,11,21;
3,7,2,19,22;
4,9,10,13,8]
figure
colormap(gray)
imagesc(ones(15,15))
axis off
for t = 1:15
for k = 1:15
text(t, k, sprintf('%c', A(t,k) + 96))
end
end
And I want to draw a line between one position and another say from (1,2) to (4,5) how can I achieve this, I think I can use either the plot or line functions but am not sure how to use them.
If I didn't get anything wrong:
A = [5,16,18,4,9;
9,10,14,3,18;
2,7,9,11,21;
3,7,2,19,22;
4,9,10,13,8]
figure
colormap(gray)
imagesc(ones(5,5))
axis off
for t = 1:5
for k = 1:5
text(t, k, sprintf('%c', A(t,k) + 96))
end
end
hold on;
line([1 2], [4 5]);
Result: