I would like to plot a line, and in grey-shaded X% deviation of a signal, in MATLAB. Then, I'd plot another signal and see (visually) how much of the second signal is outside the gret-shaded area.
The task I'd like to get help done is the shaded area: similar to the image attached below.
I am aware of similar solutions with errorbar, but I think this is a much clearer plot to visualize.
If for example I had:
x = 0:0.1:10;
y = 1 + sin(x);
What would the 5% grey-shaded plot of y look like? (that area?)
See this answer for an example: MATLAB fill area between lines
Do you have the error of y at each sample in x? Let's assume you have and the upper bound is in variable yu and the lower bound in variable yl. Then you could plot it using:
x = 0:0.1:10;
y = 1 + sin(x);
% I create some yu and yl here, for the example
yu = y+.1;
yl = y-.1;
fill([x fliplr(x)], [yu fliplr(yl)], [.9 .9 .9], 'linestyle', 'none')
hold all
plot(x,y)
fill(X,Y,ColorSpec,...) plots a polygon with edges specified in the first two parameters. You have to fliplr (flip left-right) the arrays, so that it correctly draws the shape of the area to be filled 'in a circle' around it. The [.9 .9 .9] is the colour specification, in this case a light grey. I removed the edge by setting no line, to make it even more similar to your desired plot. One detail: plot the filled area before plotting y, because the last plotted object goes on top of the others.
Related
Have a look at the following MATLAB code and the resulting surface plot. Maybe I am doing a stupid mistake, but there is actually a row and column missing. The variable z is a 10x10 matrix, but the plot shows only 9x9 elements. How to plot the whole 10x10 matrix?
z = randn(10,10);
t = 1:10;
x = 1:10;
figure;
surf(t,x,abs(z),'EdgeColor','none');
axis xy; axis tight; colormap(jet); view(0,90);
I think this is a misunderstanding about what surf does, i.e. what a surface plot is:
What you seem to be wanting is an actual image instead of a surface plot, where for the former pixels correspond to the underlying values. What you get with surf is a graphical representation of lines at a certain height (abs(z) in your case), i.e. between your desired image pixels. Note that there are 10x10 lines in your 9x9 plot.
What you want can be achieved visually e.g. by:
z = randn(10,10);
t = 1:10;
x = 1:10;
figure
imshow(abs(z),[]),
axis on, colormap(gca,jet)
colorbar
hope this helps!
So I have data in the form [x y z intensity] that I plot on a scatter3 figure with xyz axes. The colour of the data is used to dictate the intensity value. Problem is, using a scatter plot means the data points show up as discrete points. What I need, is a smooth shape - so I guess I need some kind of interpolation between the points?
I've tried using trisurf, but the problem with this one is that it interpolates between points that it shouldn't. So where I should have 'gaps' in my surface, it joins up the edges instead so it fills in the gaps. See the attached pics for clarification.
Does anyone have any suggestions?
The code I use is as below (the commented out scatter3 is what does the scatter plot, the rest does the trisurf):
% Read in data
dataM = csvread('3dDispersion.csv');
% scatter3(dataM(:,1), dataM(:,2), dataM(:,3), 5, dataM(:,4),'filled');
% Plot
hold on;
x = dataM(:,1);
y = dataM(:,2);
freq = dataM(:,3);
tri = delaunay(x,y);
h = trisurf(tri, x, y, freq);
% Make it pretty
% view(-45,30);
view(3);
axis vis3d;
lighting phong;
shading interp;
Use the boundary function in Matlab. This will apply a mesh similar to shrinkwrap over your points. In order to reduce the "gap closers", you will want to increase the "shrink factor".
Try K = boundary(X,Y,Z,0.9)
Where X, Y & Z are the vectors of your data points
https://www.mathworks.com/help/matlab/ref/boundary.html
You can then use trimesh or related surface plotting functions depending on how you want to display it.
Say I have a matrix hey 15x15. I want to plot the value of the matrix as a 2D plot for better visualization. But Matlab plots with the convention that origin is in bottom-left corner and positive x is along the left and positive y is along the up direction from origin.
but i want to make my plots such that origin is in top-left corner, +ve x is left and +ve y is down.
So i just used a slight trick.
figure
axis([0 15 -15 0]);
daspect([1,1,1])
hold on
rectangle('Position',[3,-6,2,3],...
'EdgeColor','black',...
'LineWidth',2,...
'FaceColor','cyan')
for i=1:nrows
for j=1:ncolumns
if char(hey(i,j))=='^'
text(j,-i,'^');
elseif char(hey(i,j))=='>'
text(j,-i,'>');
elseif char(hey(i,j))=='v'
text(j,-i,'v');
elseif char(hey(i,j))=='<'
text(j,-i,'<');
end
if obstacle(i,j)==1
text(j,-i,'X');
end
end
end
text(goalY,-goalX,'T');
I made the transformation (x,y)-->(y,-x). But the downside is that the axes are then numbered along y as -1 to -15. However if reader was following above, i only wanted to plot the matrix values and in matrix the y runs +ve downwards from 1 to 15 for my case.
So i want the plot to show +1 thru +15 along y with origin at top-left and x graduated as it is but the values +1 to +15 written at the top of the plot rather than below.
How to do this? In the extreme case, i am alos willing to transfer the matrix hey to another software that can do the nice plot as i want. If any of the two alternatives is possible, please give concrete steps to do it.
EDIT:
After using the helpful methods below, i still have to use a trick like plot (j,i) instead of the innocent plot(i,j). This is because for matrix (i,j) is mapped to graph plot (x,y) as x=j, y=i. Is there a similar workaround? a matrix element is (row #, column #). But in 2D matlab graph, we will denote it's position as (column #, row #). I was just guessing if there was some matlab in-built function to take care of this. like i will give it (row #, column #) but matlab will plot (column #, row #). Is there such a function?
I think axis ij does what you want:
axis ij places the coordinate system origin in the upper left corner. The i-axis is vertical, with values increasing from top to bottom. The j-axis is horizontal with values increasing from left to right.
To locate the x axis on top, change the 'XAxisLocation' of the axes to 'top' (default is 'bottom').
Example:
x = 1:10;
y = x.^2;
plot(x,y)
axis ij
set(gca,'XAxisLocation','top')
Original plot (lines 1-3 of above code):
After axis ij (line 4):
After set(gca,'XAxisLocation','top') (line 5):
If I followed correctly you are looking for the axes XAxisLocation and YDir properties. You can set them to top and reverse respectively to get the output you want. You can also set the XTick property to 1:15 to show every value from 1 to 15.
Example:
clear
clc
%// Create dummy data
[x,y] = meshgrid(1:15,1:15);
u = cos(x).*y;
v = sin(x).*y;
figure
quiver(x,y,u,v)
set(gca,'XAxisLocation','top','XTick',1:15,'YDir','reverse')
hold on
%// I changed the coordinated of the rectangle to fit with the change in
%y-axis.
rectangle('Position',[3,3,2,3],...
'EdgeColor','black',...
'LineWidth',2,...
'FaceColor','cyan')
axis([0 15 0 15])
Which gives the following:
I have a figure which consists of different levels of a contour plotted using the hold on function. I want to fill the space between the levels of contour with a color. Could you please assist me how can I do that. I have already tried the contourf function. The figure consists of different red colored levels of a contour, what I want is a solid color filled between these contour levels.
I am not sure if I got exactly what you wanted but here goes a possible solution to your problem.
If you plotted using the hold on function I would therefore assume you have each contour in a different variable. If so you can use logic to check whether a contour is higher or lower relatively to another. If your problem is that you do not have the same x axis for each so that you can use logic just interpolate for each contour (for example between -0.8 and 0.8)
I will give an example of what I am saying. See if this helps.
%simulated contours
x=linspace(0,pi,100);
y = sin(x);
y2 = sin(x)*2;
y3 = sin(x)*3;
figure, hold on,
plot(x,y),
plot(x,y2),
plot(x,y3),
%fill contours
[X,Y]=meshgrid(x,0:3/100:3);
zzz=(Y<repmat(y,size(Y,1),1))+(Y<repmat(y2,size(Y,1),1))+(Y<repmat(y3,size(Y,1),1));
figure,imagesc(zzz)
set(gca,'YDir','normal')
I have a script to create scatter plots (using gscatter) based on x-y data (discrete data points, not continuous) produced by another script. Since these data points are actually the locations of certain objects in a circular space, adding polar grid lines will make the plots more meaningful.
Does anyone know how to show polar grid lines on a Cartesian scatter plot, or am I better off using polar plots?
I once made this script for drawing a polar coordinate system on top of a regular plot. Perhaps it can be useful for you. It is based on this script but simplified to only draw the coordinate system and no data. If this wasn't what you were looking for, check out the linked script, perhaps it can help as well.
Be sure to tweak the radius as needed! I usually disable the axis but it's up to you to fix that if you need another look :)
R=6000; %radius
S=10; %num circ.lines
N=10; %num ang.lines
sect_width=2*pi/N;
offset_angle=0:sect_width:2*pi-sect_width;
%------------------
r=linspace(0,R,S+1);
w=0:.01:2*pi;
clf %remove if needed
hold on
axis equal
for n=2:length(r)
plot(real(r(n)*exp(j*w)),imag(r(n)*exp(j*w)),'k--')
end
for n=1:length(offset_angle)
plot(real([0 R]*exp(j*offset_angle(n))),imag([0 R]*exp(j*offset_angle(n))),'k-')
end
%------------------
You can always use the pol2cart function to generate the polar grid lines.
For example:
function DrawGridLines
x = randn(10);
y = randn(10);
figure;scatter(x(:),y(:));
hold on ;
for angle = 0:20:(360-20)
[x1,y1] = pol2cart( angle / 180 * pi , [0 2]);
plot(x1,y1,'r')
end
for rho = 0:0.1:2
[x1,y1] = pol2cart( 0:0.01:2*pi , rho);
plot(x1,y1,'b')
end
axis equal
end