I have a set of data that I'm trying to analyse using the pwelch function of Matlab , my problem is that I have 13 curves and I get more , I want to label each curves, so i can deffirenciate between them, I tried using legend, but it didn't help .
here is my code and the result that I get:
clear, clc , clf;
M = 512;
k = 1
hold all;
grid on ;
for i =1:13
pause(2)
fileName =['M',int2str(i),'.wav']
[x,fs] = audioread(fileName);
[xPSD,f] = pwelch(x,hann(2048),1024,2048*4 ,fs);
plot(f,10*log10(xPSD))
text(7,30,fileName);
xlim([0 15e3]);
Leg{i} =['qho-',num2str(i)];
end
legend(Leg)
thanks for your help!
Related
Suppose I have a 5x5 matrix.
The elements of the matrix change (are refreshed) every second.
I would like to be able to display the matrix (not as a colormap but with the actual values in a grid) in realtime and watch the values in it change as time progresses.
How would I go about doing so in MATLAB?
A combination of clc and disp is the easiest approach (as answered by Tim), here's a "prettier" approach you might fancy, depending on your needs. This is not going to be as quick, but you might find some benefits, such as not having to clear the command window or being able to colour-code and save the figs.
Using dispMatrixInFig (code at the bottom of this answer) you can view the matrix in a figure window (or unique figure windows) at each stage.
Example test code:
fig = figure;
% Loop 10 times, pausing for 1sec each loop, display matrix
for i=1:10
A = rand(5, 5);
dispMatrixInFig(A,fig)
pause(1)
end
Output for one iteration:
Commented function code:
function dispMatrixInFig(A, fig, strstyle, figname)
%% Given a figure "fig" and a matrix "A", the matrix is displayed in the
% figure. If no figure is supplied then a new one is created.
%
% strstyle is optional to specify the string display of each value, for
% details see SPRINTF. Default is 4d.p. Can set to default by passing '' or
% no argument.
%
% figname will appear in the title bar of the figure.
if nargin < 2
fig = figure;
else
clf(fig);
end
if nargin < 3 || strcmp(strstyle, '')
strstyle = '%3.4f';
end
if nargin < 4
figname = '';
end
% Get size of matrix
[m,n] = size(A);
% Turn axes off, set origin to top left
axis off;
axis ij;
set(fig,'DefaultTextFontName','courier', ...
'DefaultTextHorizontalAlignment','left', ...
'DefaultTextVerticalAlignment','bottom', ...
'DefaultTextClipping','on');
fig.Name = figname;
axis([1, m-1, 1, n]);
drawnow
tmp = text(.5,.5,'t');
% height and width of character
ext = get(tmp, 'Extent');
dy = ext(4);
wch = ext(3);
dwc = 2*wch;
dx = 8*wch + dwc;
% set matrix values to fig positions
x = 1;
for i = 1:n
y = 0.5 + dy/2;
for j = 1:m
y = y + 1;
text(x,y,sprintf(strstyle,A(j,i)));
end
x = x + dx;
end
% Tidy up display
axis([1-dwc/2 1+n*dx-dwc/2 1 m+1]);
set(gca, 'YTick', [], 'XTickLabel',[],'Visible','on');
set(gca,'XTick',(1-dwc/2):dx:x);
set(gca,'XGrid','on','GridLineStyle','-');
end
I would have thought you could achieve this with disp:
for i=1:10
A = rand(5, 5);
disp(A);
end
If you mean that you don't want repeated outputs on top of each other in the console, you could include a clc to clear the console before each disp call:
for i=1:10
A = rand(5, 5);
clc;
disp(A);
end
If you want to display your matrix on a figure it is quite easy. Just make a dump matrix and display it. Then use text function to display your matrix on the figure. For example
randMatrix=rand(5);
figure,imagesc(ones(20));axis image;
hold on;text(2,10,num2str(randMatrix))
If you want to do it in a for loop and see the numbers change, try this:
for i=1:100;
randMatrix=rand(5);
figure(1),clf
imagesc(ones(20));axis image;
hold on;text(2,10,num2str(randMatrix));
drawnow;
end
I want to produce a animated gif of a solution to a partial differential equation. That is the gif should show the solution at specific time.
Currently I can only make pictures in which all times are plotted.
Below is my entire program, with figure(3) being my attempt of making a gif.
clear all;
close all;
%%%%%%%%%%%%
% For slide 27 of Diffusion 1D
% The equation to be graphed in latex form is
% u(x,t)=\frac{1}{L}+\frac{2}{L}\sum^{\infty}_{n=1}cos(\frac{n\pi x_0}{L})cos(\frac{n\pi x}{L})e^{-k(\frac{n\pi}{L})^2t}
%%%%%%%%%%%%
%define constants
%note that the constants listed in the file are arbitrary
L = 2; %length of the rod
k= 0.01; % Diffusivity, which is assume to be constant but can be a function of x
x0 = 1; %location of the inital condition i.e. f(x)=delta(x-x0)
tmax= 50; %maximum amount of time the simulation runs
nmax = 200; % maximum value for n, increase to accuracy
tgrid = 21; %The number of points to be evaluated in the time domain
xgrid = 51; %The number of points to be evaluated in the space domain
%initialize variables
u=zeros(tgrid,xgrid); %preallocate array used for storing values of the solution
t=linspace(0,tmax,tgrid);%We assume that time is evenly distributed
x=linspace(0,L,xgrid); %We assume that space is evenly distributed
%Plotting variables
figure(1);
hold on;
axis([0 L -inf inf]);
xlabel('x');
ylabel('u(x,t)');
%Calculation,
for i=1:tgrid
for j=1:xgrid
seriesSum=0;
%Calculate the fourier series up to nmax for each point u(x,t)
for n= 1:nmax
seriesSum= seriesSum + cos(n*pi*x0/L)*cos(n*pi*x(j)/L)*exp(-k*t(i)*(n*pi/L)^2);
end
%Finish calcuation for solution at a specific point
u(i,j)= 1/L+(2/L)*seriesSum;
end
%After we have calculated all points at time t, we graph it for time t
plot(x,u(i,:),'linewidth',4);
end
saveas(gcf,'PDE_sol.png')%Save figure as png in current directory
%run a second loop that does not include the initial condition to get a
%better view of the long term behaviour.
%Plotting variables
figure(2);
hold on;
axis([0 L -inf inf]);
xlabel('x');
ylabel('u(x,t)');
for i=2:tgrid
plot(x,u(i,:),'linewidth',4);
end
saveas(gcf,'PDE_sol_without_inital.png')%Save figure as png in current directory
%Create a gif verison of figure 2
figure(3);
axis([0 L -inf inf]);
xlabel('x');
ylabel('u(x,t)');
filename = 'PDE_sol.gif';
for i=2:tgrid
plot(x,u(i,:),'linewidth',4);
drawnow
frame = getframe(1);
im = frame2im(frame);
[imind,cm] = rgb2ind(im,256);
if i == 2;
imwrite(imind,cm,filename,'gif', 'Loopcount',inf);
else
imwrite(imind,cm,filename,'gif','WriteMode','append');
end
end
The output gif that I get is
which is clearly not animated.
Note: If you think there is a better place to post this question please direct me to it. As my issue is with the MATLAB programming language and not the math involved I thought this would be the best place to post my question.
The first input to getframe is the handle of the figure that you'd like to take a screenshot of. As you have it written, you are grabbing figure 1 which is actually referring to the first figure that you create that you aren't updating within your loop.
You have assigned a numeric handle of 3 to the figure that you create right before your last loop so you'll want to tell getframe to use that figure instead.
Additionally, I would create one plot object and update the XData and YData rather than continuously creating new plot objects. The issue with calling plot continuously is that it's slow AND it completely resets all of your axes settings such as x and y labels as well as x and y limits.
% Store the handle to the figure in hfig
hfig = figure(3);
% Create the initial plot object
hplot = plot(NaN, NaN, 'LineWidth', 4);
axis([0 L 0 2]);
xlabel('x');
ylabel('u(x,t)');
filename = 'PDE_sol.gif';
for i=2:tgrid
% Update the plot appearance
set(hplot, 'XData', x, 'YData', u(i,:));
drawnow
% Get a screenshot of THIS figure
frame = getframe(hfig);
im = frame2im(frame);
[imind,cm] = rgb2ind(im,256);
if i == 2;
imwrite(imind,cm,filename,'gif', 'Loopcount',inf);
else
imwrite(imind,cm,filename,'gif','WriteMode','append');
end
end
i have following question and please help me to solve following task:
i want to create subplot in matlab which depend on loop variable,for example as i know to crate plot menu 2X2,we are doing like this
subplot(2,2,1)
subplot(2,2,2)
subplot(2,2,3)
subplot(2,2,4)
but can i do linear form?like 1:100?or something like this ,more generally like this
n=100;
for i=1:n
subplot(1,n,i)
?
thanks very much
EDITED CODE
function [order]=find_order(y,fs);
order=0;
n=length(y);
n1=nextpow2(n);
ndft=2^n1;
for i=1:floor(n/2)
[Pxx,f]=pburg(y,i,ndft,fs);
subplot(ndft,ndft,i);
plot(f,Pxx);
title(['order',num2str(i),'i']);
order=i;
end
end
picture :
i can't understand what happens
1-D Demo
Code
%%// Data
t = 0:0.01:15*pi;
y1 = sin(t);
%%// Plot
figure,
for k=1:4
subplot(4,1,k)
plot(t((k-1)*1000+1:k*1000),y1((k-1)*1000+1:k*1000))
xlim([0 40])
end
Output
2-D Demo
Code
%%// Data
t = 0:0.01:15*pi;
y1 = sin(t);
%%// Plot
colors=['r' 'g' ; 'y' 'k'];
figure,
for k1=1:2
for k2=1:2
subplot(2,2,(k1-1)*2+k2)
plot(t,y1,colors(k1,k2));
end
end
Output
Hopefully these demos would guide to you something meaningful for your case.
Yes, it is:
n=5;
for i=1:n
subplot(1,n,i)
end
gives
for pat=1: N % main loop
% Define the sublot grid
s1=3; % subplot rows
s2=3; % subplot columns
% find the figure number
fig_num=floor(pat/(s1*s2))+1 % Figure number
% Find the subplot number
sub_fig=mod(pat,s1*s2) % subplot number
% correct for corners
if(sub_fig==0)
sub_fig=s1*s2;
fig_num=fig_num-1;
end
% plot something
figure(fig_num);
subplot(s1,s2,sub_fig) ;
plot(1,1) % plot something
end % of main loop
Trying to engineer the following in Matlab:
** loop start;
y(:,i) = function of x;
z(:,i) = function of x;
plot(x,y(:,i)) on figure 1, hold all;
plot(x,z(:,i)) on figure 2, hold all;
** loop end;
add title, legend, etc for figure 1 (NB: we have multiple lines);
add title, legend, ets for figure 2 (NB: same, have multiple lines for the legend);`
Tried multiple combinations without much luck. Managed to get 2 figures but only the 2-nd displays multiple lines, not the first. And can't figure how to add legends to these 2 correctly.
Save a handle to each figure, and to each axis object:
fh1 = figure;
hold all;
ah1 = gca;
fh2 = figure;
hold all;
ah2 = gca;
for i=1:N
y(:,i) = function of x;
z(:,i) = function of x;
plot(ah1, x, y(:,i)); %# tell it which axis to use (ah1)
plot(ah2, x, z(:,i)); %# (ah2)
end
legend(ah1, ...) %# legend options here
legend(ah2, ...) %# and the other legend
%# note: you can set figure properties for each using fh1, fh2 handles.
You can do this:
figHandle1 = figure(1);
figHandle2 = figure(2);
Then when you want to plot on that figure do this:
figure(figHandle1) %Plot on figure 1
%ie plot(someStuff)
figure(figHandle2) %Plot on figure 2
Also its the same for the title and stuff, you jjust need to identify which figure by doing:
figure(handle);
Hope this helps.
I have been currently using a Matlab script that plots a function and prints its data into a png file, but I have a problem with this last phase.
The fact is that, moving from plotted image to png files, some data points disappear.
Here are my images.
What Matlab (correctly) plots (note that the maximum is (0; 7.7)):
And here's what Matlab prints into the file:
Note that all the points in the Y asymptote are missing!
Why does this happen?
Here's my code:
grafico2D('filename.dat', -1);
...
function [result] = grafico2D(filename, max_X)
% function that loads data from a two-column file and plot them in 2D image
close all;
dati = load(filename); % load data from file
X = dati(:,1); % X axis
Y = dati(:,2); % Y axis
temp = size(X);
lungX = temp(1);
hFig = figure();
set(hFig, 'Visible', 'on');
plot(X, Y, 'red');
hold on;
ylim([0 1]);
if(max_X==-1)
xlim([1 X(lungX)]);
else
xlim([1 max_X]);
end
xlim
title(strrep(filename,'_','\_')); % substitute _ with \_
xlabel('annotation prediction position'), ylabel('likelihood');
grid
print(hFig, '-dpng', filename); % stampa su file
% }
result = 1;
end
Is there someone who can help me?
Thanks!
You can increase the resolution of your image with the -r option which specifies the resolution in dot per inch (with 90 as default). It should solve your problem (at least it did for me). See the Matlab print function documentation.
PS: you could also use thicker lines with the line property LineWidth.
You could just extend the x-limit a little bit:
xlim(xlim() - [0.05 0])