Is there an easy command to have a plot like the blue line in the picture (excel)? Matlab defaults to produce something like the line in red. The only way I know to do this is to issue a plot command for each segment of the line:
for i=2:n-1
plot([data(i-1,1) data(i,1)],[data(i-1,2) data(i,2)],'-b'); hold on;
end
You can just plot the entire array and let plot automatically draw straight line segments between each of the points. This is the default behaviour when plotting things in MATLAB. MATLAB plotting smooth lines is not the default behaviour when the plot is produced, so I'm not sure where you're getting that information.
You would need to perform some sort of spline interpolation to get the red line, but you desire the blue curve and so plotting the entire array in a single plot command should suffice.
It's as simple as:
plot(data(:,1), data(:,2), '-b');
Just to be sure that we're on the same page, I'm going to reproduce your data then use the above command to plot the data so you can see for yourself that the behaviour you desire is achieved:
data = [0 0; 1 1; 2 4; 3 6; 4 4]; %// Your data reconstructed
plot(data(:,1), data(:,2), '-b'); %// Main plotting code
%// Some extras
xlim([0 4.5]);
ylim([0 7]);
grid;
I've added in some extra code to get the plot to look like your example. I've made the x-axis limits go up to 4.5 and the y-axis limits go up to 7. I've also placed a grid in the plot.
We get:
Related
I have a function in MATLAB and it plots two curves and I run it two times.
On the first time plot main curve as you can see in the red color (first plot) and after that turn the "hold on" and execute my function again with the green color (second shape).
The problem is that the left subplot does not work and delete the first curve (red curve) but the second one works fine (last plot).
My main script is:
% some code to processing
...
roc('r.-',data); %this function plots my curves
and on the second run
% some code to processing
...
plot on
roc('g.-',data);
and my roc function contains:
%some code
...
subplot(1,2,1)
hold on
HCO1=plot(xroc(J),yroc(J),'bo');
hold off
legend([HR1,HRC1,HCO1],'ROC curve','Random classifier','Cut-off
point','Location','NorthOutside')
subplot(1,2,2)
hold on
HCO2=plot(1-xroc(J),yroc(J),'bo');
hold off
legend([HR2,HRC2,HCO2],'ROC curve','Random classifier','Cut-off
point','Location','NorthOutside')
disp(' ')
%....
Assuming your roc function calculates xroc and yroc I suggest you rewrite your code to modularize it
function [xroc,yroc] = roc(data)
%your algorithm or training code
%xroc=...
%yroc=...
end
this way your main script could be edited to something like this
%first run
[xroc1,yroc1] = roc(data);
%...some further processing with data variable
[xroc2,yroc2] = roc(data);
%plots
ax1 = subplot(1,2,1,'nextplot','add'); %create left axes
ax2 = subplot(1,2,2,'nextplot','add'); %create right axes (mirrored roc)
%now you can go ahead and make your plots
%first the not mirrored plots
plot(xroc1,yroc1,'r','parent',ax1);
plot(xroc2,yroc2,'g','parent',ax1);
%and then the mirrored plots
plot(1-xroc1,yroc1,'r','parent',ax2);
plot(1-xroc2,yroc2,'g','parent',ax2);
it is a little effort to rewrite but it surely will help to make your code scaleable to if you want to add more than just two curves in future.
I've got 10 grayscale images. I'd like to plot a simple YELLOW line over each image separately, then show them all over one plot (montage style).
I tried to draw all images first, but that made plotting lines very tricky (X,Y axes weren't standard for plotting over each separate image).
I thought about burning the line over the image, but I don't have the computer vision toolkit (easy functions to do this), otherwise it seemed complicated to both convert the grayscale to color and get it to burn the image.
I thought I might be able to use the function newplot to create a temporary plot space for each image, draw the line with a simple plot(...) call, then save it and just montage(...) all the individual plots at the end.
Is this possible? I've never played with the function newplot or tried to loop through individual plots, saving them up for a call to montage(...) this way, but it seems like a logical/simple approach.
I finally worked it out with subplot, subimage, and plot, using subplot with the position arguments does what I want easily enough. Using subplot kept the axis relative to the subplot I was on so I could plot the line with a standard fplot/plot call. The trick was normalizing the position to percentages vs. thinking of it in terms of pixels.
here's some code demoing it:
% Loop through this code, each time moving the subplot by position
LOOP {
% calculate left & bottom position as percentages (0..1)
subplot( 'Position', [ left bottom (1/cols) (1/rows) ] );
hold on
% (1) Draw the image
subimage(tmpImg, [0 255]);
axis off;
% (2) Plot the line over the original image
F = #(x) polyval(p, x);
fplot(F, [1 dimX 1 dimY], '-y');
}
I need to make a plot with only points and tried something like
plot(x,y)
where x and y are vectors: collection of points.
I do not want matlab to connect these points itself. I want to plot as if plotted with
for loop
plot;hold on;
end
I tried
plot(x,y,'.');
But this gave me too thick points.
I do not want to use forloop because it is time expensive. It takes a lot of time.
You're almost there, just change the MarkerSize property:
plot(x,y,'.','MarkerSize',1)
Try:
plot(x,y,'*');
or
plot(x,y,'+');
You can take a look to the documentation: http://www.mathworks.nl/help/matlab/creating_plots/using-high-level-plotting-functions.html
help scatter
IIRC: where S is the size of the scatter points:
scatter(x,y,S)
You may try this piece of code that avoid using loops. The plot created does not have lines but markers of different colors corresponding to each column of matrices x and y.
%some data (matrix)
x = repmat((2:10)',1,6);
y = bsxfun(#times, x, 1:6);
set(0,'DefaultAxesColorOrder', jet(6)); %set the default matlab color
figure('Color','w');
plot(x,y,'p'); %single call to plot
axis([1 11 0 70]);
box off;
legend(('a':'f')');
This gives
All the three variables I am using to plot are matrix of size 1x1x100. I am using this code line to plot:
hold on;
for i=1:100
plot3(R_L(:,:,i),N_Pc(:,:,i),CO2_molefraction_top_of_window(:,:,i),'o');
xlabel('R_L');
ylabel('N_P_c');
zlabel('CO_2')
end
However, I am not getting the third axis, and hence the third variable CO2_molefraction_top_of_window on the plot. May I know where am I wrong?
Besides the above question, but on the same subject, I want to know if there is any option where I can plot 4 dimensional plot just like the 3 dimensional plot which can be drawn using plot3?
So I had the same problem when using plot3. For some reason, using the hold on command "flattens" the plot. I'm not sure why, but I suspect it has something to do with the operation hold on performs on the plot.
Edit: To clarify, the 3d plot is still there, but the perspective has been forced to change. If you use the "rotate 3D" tool (the one with an arrow around a cube), you can see the graph is 3d, the default perspective is just straight on so only two axes are visible and it appears flat.
Just a note --- you only need to do the xlabel ylabel zlabel commands once (outside the loop).
Also:
is there any reason your matrices are 1x1x100 instead of just 100x1 or 1x100?
Because if you reshape them to 2D you can just do the plotting in one hit.
What do you mean by "missing third axis"? When I run your code (or as close as I can get, since you didn't provide a reproducible example), I do get a 3rd axis:
.
X = rand(1,1,100); % 1x1x100 X matrix
Y = rand(1,1,100); % 1x1x100 Y matrix
Z = rand(1,1,100); % 1x1x100 Z matrix
% Now, we could do a for loop and plot X(:,:,i), Y(:,:,i), Z(:,:,i),
% OR we can just convert the matrix to a vector (since it's 1x1x100 anyway)
% and do the plotting in one go using 'squeeze' (see 'help squeeze').
% squeeze(X) converts it from 1x1x100 (3D matrix) to 100x1 (vector):
plot3(squeeze(X),squeeze(Y),squeeze(Z),'o')
xlabel('x')
ylabel('y')
zlabel('z')
This gives the following, in which you can clearly see three axes:
If it's the gridlines that you want to make the graph look "more 3D", then try grid on (which is in the examples in the Matlab help file for plot3, try help plot3 from the Matlab prompt):
grid on
You will have to clarify "missing third axis" a bit more.
I came across a similar problem and as #Drofdarb's the hold on seems to flatten out one axis. Here is a snippet of my code, hope this helps.
for iter = 1:num_iters:
% hold on;
grid on;
plot3(tita0,tita1, num_iters,'o')
title('Tita0, Tita1')
xlabel('Tita0')
ylabel('Tita1')
zlabel('Iterations')
hold on; % <---- Place here
drawnow
end
As opposed to:
for iter = 1:num_iters:
grid on;
hold on; % <---- Not here
plot3(tita0,tita1, num_iters,'o')
title('Tita0, Tita1')
xlabel('Tita0')
ylabel('Tita1')
zlabel('Iterations')
% hold on;
drawnow
end
How can I make plots in MATLAB like in below?
I won't need labels, so you can ignore them. I tried using normal 2D plot, by giving 0 to y parameter for each data points. It does help, but most of the plot remains empty/white and I don't want that.
How can I solve this problem?
Edit:
This is how I plot(playing with values of ylim does not help):
hold on
for i=1:120
if genders(v_labels(i)) == CLASS_WOMAN
plot(v_images_lda(i,:) * w_lda,0,'r*');
else
plot(v_images_lda(i,:) * w_lda,0,'b.');
end
end
title('LDA 1D Plot');
ylim([-0.2 0.2]);
hold off
One way to do this would be to adjust the 'XLim', 'YLim', and 'DataAspectRatio' properties of the axes so that it renders as essentially a single line. Here's an example:
data1 = rand(1,20)./2; %# Sample data set 1
data2 = 0.3+rand(1,20)./2; %# Sample data set 2
hAxes = axes('NextPlot','add',... %# Add subsequent plots to the axes,
'DataAspectRatio',[1 1 1],... %# match the scaling of each axis,
'XLim',[0 1],... %# set the x axis limit,
'YLim',[0 eps],... %# set the y axis limit (tiny!),
'Color','none'); %# and don't use a background color
plot(data1,0,'r*','MarkerSize',10); %# Plot data set 1
plot(data2,0,'b.','MarkerSize',10); %# Plot data set 2
And you will get the following plot:
Here's one way to reproduce your figure using dsxy2figxy and annotate. dsxy2figxy can be hard to find the first time, as it is not really in your path. It is part of the MATLAB package and is provided in the example functions. You can reach it by searching for it in the help docs and once you find it, open it and save it to a folder in your path.
h1=figure(1);clf
subplot(4,1,1);
hold on
xlim([0.2,1]);ylim([-1,1])
%arrow
[arrowX,arrowY]=dsxy2figxy([0.2,1],[0,0]);
annotation('arrow',arrowX,arrowY)
%crosses
x=[0.3,0.4,0.6,0.7,0.75];
plot(x,0,'kx','markersize',10)
%pipes
p=[0.5,0.65];
text(p,[0,0],'$$\vert$$','interpreter','latex')
%text
text([0.25,0.5,0.65],[1,-1,-1]/2,{'$$d_i$$','E[d]','$$\theta$$'},'interpreter','latex')
axis off
print('-depsc','arrowFigure')
This will produce the following figure:
This is sort of a hackish way to do it, as I've tricked MATLAB into printing just one subplot. All rasterized formats (jpeg, png, etc) will not give you the same result, as they'll all print the entire figure including where the non-declared subplots should've been. So to get this effect, it has to be an eps, and it works with it because eps uses much tighter bounding boxes... so all the meaningless whitespace is trimmed. You can then convert this to any other format you want.
Ok so the closest I have come to solving this is the following
hax = gca();
hold on
for i=1:120
if genders(v_labels(i)) == CLASS_WOMAN
plot(v_images_lda(i,:) * w_lda,0,'r*');
else
plot(v_images_lda(i,:) * w_lda,0,'b.');
end
end
set(hax, 'visible', 'off');
hax2 = axes();
set(hax2, 'color', 'none', 'ytick', [], 'ycolor', get(gcf, 'color');
pos = get(hax, 'position');
set(hax2, 'position', [pos(1), pos(2)+0.5*pos(4), pos(3), 0.5*pos(4)]);
title('LDA 1D Plot');
hold off
So in short, I hid the original axis and created a new one located at 0 of the original axis, and as I couldn't remove the y axis completely I set it's color to the background color of the figure.
You can then decide if you also want to play with the tick marks of the x-axis.
Hope this helps!
Very naive trick but a useful one.
Plot in 2d using matlab plot function. Then using edit figure properties compress it to whichever axis you need a 1D plot on !! Hope that helps :)