I'd like to create 4 subplots each containing 16 figures. Each figure is one dimension of the matrix GW. I.e. GW(:,:,1) is the first image.
Here is my for loop for the first 16 images in first subplot. How should I modify the for loop to get 3 more subplots?
The first subplot should contain first 16 images, second subplot should contain second 16 images and so on. With the following loop I'm getting first 16 images for all the four subplots.
for i=1:4
figure(i);
hold on;
for jj = 1:16
subplot (4,4,j)
imshow (GW(:,:,j));
end
end
You just need to modify how you access the 3rd dimension of GW. Try this:
num_figures = 4; % because I dont like magic numbers in the code
subplots_per_figure = 16; % same here
for i=1:num_figures
figure(i);
hold on;
for j = 1:subplots_per_figure
subplot (4,4,j)
imshow (GW(:,:,j+(i-1)*subplots_per_figure));
end
end
Related
I am looking for a way to add vertical dividing lines separating consecutive days in a dynamically updating plot of animal migration data (location vs. time). Part of the challenge is that the number of these dividers changes as the plot domain expands to display more temporal data: As the number of days in the plot increases from 3 to 5, for example, the number of dividers increases by 2.
A minimal code example, written in MATLAB, is shown below:
xcols = [1; 1];
ycols = [0; 1];
figure(4)
clf
h.divs = plot(xcols,ycols,':k');
xlabel('time')
ylabel('location')
for ii=2:6
xcols(:,end+1) = [ii; ii];
ycols(:,end+1) = [0; 1];
% set(h.divs, 'XData', xcols, 'YData', ycols);
% set(h.divs, {'XData'}, num2cell(xcols',2), {'YData'}, num2cell(ycols',2));
drawnow
pause(1)
end
The problem centers on the two lines that have been commented out. If I comment in the first of these to try to update XData and YData with each new set of dividers (given as the 2 x DividerCount matrices xcols and ycols), then I receive an error that these inputs "must be a vector of numeric type". If I instead comment in the second line as way of using cell arrays to get around this (per this Stack Overflow post and this MATLAB Newsgroup post), then the code returns an error that "cell array handle dimension must match handle vector length" as soon as the number of dividers changes.
Hacky solutions are certainly possible. For example, the dividers can be plotted as a single line of horizontal and vertical segments, where the horizontal segments are placed above and below the y-axis limits of the plot. Or a fixed number of dividers can be used, with some of the dividers plotted outside the x-axis limits of the plot. The question is whether there is a non-hacky approach – one that can plot a potentially changing number of lines of identical style in the same figure with each pass of the loop.
Assume we have at the beginning
xcols = [1:3; 1:3];
ycols = [0 0 0; 1 1 1];
then h.divs = plot(xcols,ycols,':k'); will create 3 line objects.
Using
set(h.divs,{'XData'},num2cell(xcols',2),{'YData'},num2cell(ycols',2));
with size(xcols, 2)>3 will fail, because this assumes there are more than 3 graphics objects to set values for (but numel(h.divs) is still 3).
So do we have to create a new plot for every divider?
No!, because if we insert NaNs into our data, we can introduce gaps into lines.
As a first iteration, we could use this:
xcols = [1 1];
ycols = [0 1];
figure(4)
clf
h.divs = plot(xcols,ycols,':k');
for ii=2:6
xcols(end+(1:3)) = [nan ii ii];
ycols(end+(1:3)) = [nan 0 1];
set(h.divs, 'XData', xcols, 'YData', ycols);
drawnow
pause(1)
end
Starting with one divider which we plot, we then grow the data vectors (one-dimensional!) with a new value pair separated from the old data by a nan.
This of course grows the data vectors in the loop, which is not so great. Instead, if we know how many dividers there will be, we can preallocate with NaNs and only fill in new data in the loop:
n_div = 6;
xcols = nan(3 * n_div, 1);
ycols = nan(3 * n_div, 1);
figure(4)
clf
h.divs = plot(xcols,ycols,':k');
for ii=1:6
xcols((ii - 1)*3 + (1:2)) = [ii ii];
ycols((ii - 1)*3 + (1:2)) = [0 1];
set(h.divs, 'XData', xcols, 'YData', ycols);
drawnow
pause(1)
end
This has also the benefit that we can assign XData and YData separately, as in the new handle syntax:
h.divs.XData = xcols;
h.divs.YData = cols;
(or even better: h.divs.XData((ii - 1)*3 + (1:2)) = [ii ii];), because the lengths don't change.
You can start with divider definition:
divider.x=[];
divider.y=[];
divider.counter=0;
h.div=line('xdata',divider.x,'ydata',divider.y,'linestyle',':','color','k');
Which will draw no line, but handle will be set.
Then, perhaps in some loop, you can call:
divider.counter=divider.counter+1; % increase the counter
divider.x=[divider.x,nan,divider.counter*[1 1]]; % append X coords of new divider line
divider.y=[divider.y,nan,divider.counter*[0 1]]; % append Y coords of new divider line
set(h.div,'xdata',divider.x,'ydata',divider.y) % update dividers
drawnow % update figure immediately
This approach works because NaN value can be passed to line function but will not be plotted and neither will be lines from neighbour points.
I have the pixel locations of P points on a -constant- image, for T iterations of an algorithm, so locations = [T x 2*P] double.
Now I want to create an animation where it plots the image, then plots the points, pauses for N seconds and updates their location to the next step. I don't know if there is a standard way to follow. I think I need something like:
figure;
imshow(img);
hold on;
for t=1:T
anim = updatePlot(locations(t,:), anim); % ?
end
How can I implement this updatePlot function?
Thanks for any help!
You can do this a couple of different ways. The first way would be to give the plotted points a handle so that you can delete them before the next iteration:
figure
imshow(img);
hold on;
for t = 1:T
% delete the previous points plotted (skip t = 1 since they won't exist)
if t > 1
delete(hPoints);
end
hPoints = plot(xLocations(t,:),yLocations(t,:),'.');
getframe;
pause(N);
end
(I am not exactly sure how you parse your locations along each row to separate the x and y components, so I've just used xLocations and yLocations to represent those values.)
The second way would be to re-draw the entire image at each iteration:
figure
for t = 1:T
clf;
imshow(img);
hold on;
plot(xLocations(t,:),yLocations(t,:),'.');
getframe;
pause(N);
end
Note that imshow might have its own getframe effect so that you'll see the image flicker before plotting the points -- if that happens just switch from imshow to image.
I have matrices x1, x2, ... containing variable number of row vectors.
I do successive plots
figure
hold all % or hold on
plot(x1')
plot(x2')
plot(x3')
Matlab or octave normally iterates through ColorOrder and plot each line in different color. But I want each plot command to start again with the first color in colororder, so in default case the first vector from matrix should be blue, second in green, third in red etc.
Unfortunately I cannot find any property related to the color index niether another method to reset it.
Starting from R2014b there's a simple way to restart your color order.
Insert this line every time you need to reset the color order.
set(gca,'ColorOrderIndex',1)
or
ax = gca;
ax.ColorOrderIndex = 1;
see:
http://au.mathworks.com/help/matlab/graphics_transition/why-are-plot-lines-different-colors.html
You can shift the original ColorOrder in current axes so that the new plot starts from the same color:
h=plot(x1');
set(gca, 'ColorOrder', circshift(get(gca, 'ColorOrder'), numel(h)))
plot(x2');
You can wrap it in a function:
function h=plotc(X, varargin)
h=plot(X, varargin{:});
set(gca, 'ColorOrder', circshift(get(gca, 'ColorOrder'), numel(h)));
if nargout==0,
clear h
end
end
and call
hold all
plotc(x1')
plotc(x2')
plotc(x3')
Define a function that intercepts the call to plot and sets 'ColorOrderIndex' to 1 before doing the actual plot.
function plot(varargin)
if strcmp(class(varargin{1}), 'matlab.graphics.axis.Axes')
h = varargin{1}; %// axes are specified
else
h = gca; %// axes are not specified: use current axes
end
set(h, 'ColorOrderIndex', 1) %// reset color index
builtin('plot', (varargin{:})) %// call builtin plot function
I have tested this in Matlab R2014b.
I found a link where a guy eventually solves this. He uses this code:
t = linspace(0,1,lineCount)';
s = 1/2 + zeros(lineCount,1);
v = 0.8*ones(lineCount,1);
lineColors = colormap(squeeze(hsv2rgb(t,s,v)))
ax=gca
ax.ColorOrder = lineColors;
Which should work for you assuming each of your matrices has the same number of lines. If they don't, then I have a feeling you're going to have to loop and plot each line separately using lineColors above to specify an RBG triple for the 'Color' linespec property of plot. So you could maybe use a function like this:
function h = plot_colors(X, lineCount, varargin)
%// For more control - move these four lines outside of the function and make replace lineCount as a parameter with lineColors
t = linspace(0,1,lineCount)'; %//'
s = 1/2 + zeros(lineCount,1);
v = 0.8*ones(lineCount,1);
lineColors = colormap(squeeze(hsv2rgb(t,s,v)));
for row = 1:size(X,1)
h = plot(X(row, :), 'Color', lineColors(row,:), varargin{:}); %// Assuming I've remembered how to use it correctly, varargin should mean you can still pass in all the normal plot parameters like line width and '-' etc
hold on;
end
end
where lineCount is the largest number of lines amongst your x matrices
If you want a slightly hacky, minimal lines-of-code approach perhaps you could plot an appropriate number of (0,0) dots at the end of each matrix plot to nudge your colourorder back to the beginning - it's like Mohsen Nosratinia's solution but less elegant...
Assuming there are seven colours to cycle through like in matlab you could do something like this
% number of colours in ColorOrder
nco = 7;
% plot matrix 1
plot(x1');
% work out how many empty plots are needed and plot them
nep = nco - mod(size(x1,1), nco); plot(zeros(nep,nep));
% plot matrix 2
plot(x2');
...
% cover up the coloured dots with a black one at the end
plot(0,0,'k');
I'm trying to plot several subplots in a single figure.
The total number of subplots is dependent on the maximal value in a matrix: maximal value of 'i'.
I'd like to plot two variables in two subplots below each other for every value of i :slagtijd_start & slagfrequentie_start
So when the maximum value of i = 3, we have a subplot matrix of 2x3 axes,
if i = 4 --> 2x4 axes etc.
Plotting on the right postions works, except that matlab erases the previous subplots (previous values of i). In this case i = 3 and the figure only displays the two latest subplots. I've tried different things with 'hold on' etc. But I can't figure it out. It's probably a simple trick.
I've posted my code and resulting figure below,
Thanks in advance,
Mochje
figure(6)
hold on
for i = 1:max(piektijden_start(:,2))
startnummer = find(piektijden_start(:,2) == i);
slagtijd_start= diff(piektijden_start(startnummer));
slagfrequentie_start= (60./slagtijd_start);
subplot(2,i,i),plot(piektijden_start(startnummer(1:end-1),1),slagtijd_start)
hold on
xlabel('Tijd [s]')
ylabel('Slagtijd [s]')
title('Slagtijd')
subplot(2,i,i+i),plot(piektijden_start(startnummer(1:end-1),1),slagfrequentie_start)
hold on
plot(piektijden_start(startnummer(1:end-1),1),slagfrequentie_start,'.r')
xlabel('Tijd [s]')
ylabel('Slagfrequentie [N/min]')
title('Slagfrequentie')
end
Use something like
figure(6)
hold on
max_i = max(piektijden_start(:,2));
for i = 1:max_i
%// ...
subplot(2, max_i, i)
%// ...
subplot(2, max_i, i+max_i)
%// ...
end
The second argument to subplot is the number of subplot columns. The third is the addressed subplot, such that such that the first subplot is the first column of the first row, the second subplot is the second column of the first row, and so on
I am implementing a clustering algorithm for n data points and I want to plot n data points in a figure before clustering and in another figure after clustering meaning that there should be two figures in same file with same data points.
My code is like:
X = 500*rand([n,2]);
plot(X(:,1), X(:,2), 'r.') 1
%Some coding section here
After:
symbs = {'r+','g.','bv','m*','ko'};
hold on
for i = 1: length(I)
plot(X(C==i,1), X(C==i,2), symbs{i}) 2
end
I just want to plot (1) in one figure and (2) in another.
Try subplot:
figure;
subplot(1,2,1)
plot(firstdata)
subplot(1,2,2)
plot(seconddata)
This will create two axes areas within the same figure window... from your description, this is my best guess as to what you want.
Edit: From the comments below, here is what you are doing
n=50;
X = 500*rand([n,2]);
subplot(1,2,1); #% <---- add 'subplot' here
plot(X(:,1),X(:,2),'r.')
symbs= {'r+','g.','bv','m*','ko'};
subplot(1,2,2); #% <---- add 'subplot' here (with different arguments)
hold on
for i = 1: length(I)
plot(X(C==i,1),X(C==i,2),symbs{i})
end
If all you want is a second figure window, instead of doing subplot you can simply say figure in the place where I put the second call to subplot and a new figure window will be created.
figure; #% <--- creates a figure window
n=50;
X = 500*rand([n,2]);
plot(X(:,1),X(:,2),'r.') #% <--- goes in first window
symbs= {'r+','g.','bv','m*','ko'};
figure; #% <---- creates another figure window
hold on
for i = 1: length(I)
plot(X(C==i,1),X(C==i,2),symbs{i}) #% <--- goes in second window
end
You just need to add figure before each plot to get two plots in two separated figures