I would like to plot/draw exactly this shape in MATLAB or OCTAVE. Of course I do know how to plot, and how to create rectangles, using either the plot, the line or the rectangle functions. But I have not yet managed to add this "hole" on the top side of the rectangle. I figure, it's a (half-)circle of radius 0.5 and center point (1.5|2). In OCTAVE, there is a drawCircleArc function, but I don't want to only draw that thing, but also to have the necessary coordinates defining the whole shape for further manipulation.
Here is one way (matlab/octave compatible):
% Specify all polygon points, excluding the semi-circle outline
X = [1, 0, 0, 3, 3, 2];
Y = [2, 2, 0, 0, 2, 2];
% Add semi-circle outline to array of polygon points
t = 0 : -0.01 : -pi;
X = [X, 1.5 + 0.5 * cos(t)];
Y = [Y, 2 + 0.5 * sin(t)];
% Use fill to plot the filled polygon, with desired settings
fill( X, Y, [0.8, 0.8, 0.8], 'linewidth', 1.5 );
axis( [-2, 4, -2, 4] ); axis equal;
As of 2017b you can also use polyshapes and boolean operators.
rect = polyshape([0 3 3 0], [0 0 2 2]);
t = linspace(0, 2*pi, 32);
circ = polyshape(1.5+.5*cos(t), 2+.5*sin(t));
subplot 121, hold on
plot(rect)
plot(circ)
axis equal
shape = subtract(rect, circ);
subplot 122
plot(shape)
axis equal
Related
I have the following simple MATLAB code:
figure()
x = [0, 0, 0];
y = [0, 0, 0];
z = [-10, 0, 10];
plot3(x, y, z, 'ro');
xlim([-20 20])
ylim([-20 20])
zlim([-20 20])
xlabel('x-axis')
ylabel('y-axis')
zlabel('z-axis')
With a certain camera view the resulting figure looks like this:
Now I want to know the resulting image coordinates of the three 3D points if I save the axes to an image:
img = frame2im(getframe(gca));
E.g. Point [0 0 -10] corresponds to pixel (x = ?, y = ?) in img
Is there any straightforward way to compute this mapping?
I am trying to generate the same plot as the one shown below,
, and I have written the following piece of code in MATLAB,
x1 = [0, 0, 1, 1];
x2 = [0, 1, 0, 1];
Y = [4, 3, 2, 4];
plot3(x1,x2,Y,'o','Color','r','MarkerSize',10, 'MarkerFaceColor', 'r')
hold on
[x y] = meshgrid(0:0.1:2, 0:0.1:2);
z = 1.25 + 2.5 * x + 1.5 * y;
surf(x, y, z,'FaceAlpha',0.5)
xlabel('x1');ylabel('x2');zlabel('y');
hold off
grid on
Would you please tell me how I can plot a line that connects the data point with its corresponding value of the generated surface for the same plot I generated with MATLAB.
Many thanks for your time.
I added a loop within the "hold" portion of your code.
x1 = [0, 0, 1, 1];
x2 = [0, 1, 0, 1];
Y = [4, 3, 2, 4];
plot3(x1,x2,Y,'o','Color','r','MarkerSize',10, 'MarkerFaceColor', 'r')
hold on
[x y] = meshgrid(0:0.1:2, 0:0.1:2);
z = 1.25 + 2.5 * x + 1.5 * y;
surf(x, y, z,'FaceAlpha',0.5)
xlabel('x1');ylabel('x2');zlabel('y');
for ii=1:numel(Y)
plot3( [x1(ii),x1(ii)], [x2(ii),x2(ii)], [Y(ii),1.25+2.5*x1(ii)+1.5*x2(ii)] );
end
hold off
grid on
Also, currently your surface z is hard-coded, therefore the code for the vertical line is hard-coded as well. But once you estimate your parameters for the regression, you could just as easily dynamically adjust the surface and the vertical lines.
Consider the polygon with vertices (0, 0), (1, 0), (7/10, 1), (1/2, 1/2), and (3/10, 1). Make a plot of this polygon in Matlab using the fill function. Rotate this polygon by an angle of 100 degrees using matrix-vector multiplication in Matlab with an appropriately chosen rotation matrix R. Make another plot of the rotated polygon using fill.
% Makes original polygon
X = [0 1 7/10 1/2 3/10];
Y = [0 0 1 1/2 1];
norm_poly = fill(X,Y,'k');
thetad = 100;
R = [cosd(thetad) -sind(thetad); sind(thetad) cosd(thetad)];
C = repmat([0 0], 5, 1)';
axis([-10 10 -10 10])
V = get(norm_poly,'Vertices')'; % get the current set of vertices
V = R*(V - C) + C; % do the rotation relative to the centre of the
square
set(norm_poly,'Vertices',V'); % update the vertices
How would I make to different plots to show them? Does the code to rotate make sense and answer all the requirements?
The rotation itself makes sense. To plot multiple things to the same graph use hold on after making the first plot. Alternatively you can make a new figure and plot a new fill there.
P = [0, 1, 7/10, 1/2, 3/10;
0, 0, 1, 1/2, 1];
fill(P(1,:), P(2,:), 'k');
theta = 100;
R = #(t) [cosd(t) -sind(t); sind(t) cosd(t)];
axis([-3 3 -3 3])
grid on
V = R(theta)*P;
hold on;
fill(V(1,:), V(2,:), 'k');
I'm trying to create a figure in matlab that looks like this:
desired figure
I am doing so by: (i) assigning value points to each x,y coordinate, (ii) plotting a surf, and (iii) change the view point so the third axis is not seen. Here is the code:
x = linspace(0, 1, 10);
y = linspace(0, 1, 10);
z = linspace(0, 1, 10);
z = repmat(z, 10, 1);
z = flipud(triu(z));
z(z==0) = nan;
hold off
surf(x, y, z, 'linestyle', 'none')
colormap([linspace(0.39, 1, 20)',linspace(0.58, 0.25, 20)', linspace(0.93, 0.25, 20)']);
colorbar
xlim([x(1) x(end)])
shading interp
view([90 -90])
hold on
plot(x, 1-y, 'linewidth', 2)
I get the following figure: matlab figure I get
As you can see, there a lot of white spaces above the line which I would like to be in color as well. Unfortunately, I cannot add any more grid points as calculating the actual value of the points takes a lot of time (unlike the example above).
Is there a way to have matlab draw colors in those white spaces as well?
Thanks!
You can try to use patch function to create filled polygon.
See http://www.mathworks.com/help/matlab/ref/patch.html
Try the following code:
vert = [0 1;1 1;1 0]; % x and y vertex coordinates
fac = [1 2 3]; % vertices to connect to make triangle
fvc = [1 0 0; 1 1 1; 0 0 1];
patch('Faces',fac,'Vertices',vert,'FaceVertexCData',fvc,'FaceColor','interp');
Result is close:
I was managed to get closer to the desired figure:
close all
x = linspace(0, 1, 10);
y = linspace(0, 1, 10);
%colorbar
xlim([x(1) x(end)])
%Fill rectangle.
vert = [0 0; 1 0; 1 1; 0 1]; % x and y vertex coordinates
fac = [1 2 3 4]; % vertices to connect to make squares
%patch('Faces',fac,'Vertices',vert,'FaceColor','red')
fvc = [1 0 0; 0.6 0.7 1; 0.6 0.7 1; 1 0 0]; %Color of vertices (selected to be close to example image).
patch('Faces',fac,'Vertices',vert,'FaceVertexCData',fvc,'FaceColor','interp')
hold on
%Fill lower triangle with white color.
vert = [0 0;0 1;1 0]; % x and y vertex coordinates
fac = [1 2 3]; % vertices to connect to make triangle
fvc = [1 1 1; 1, 1, 1; 1, 1, 1]; %White color
patch('Faces',fac,'Vertices',vert,'FaceVertexCData',fvc,'FaceColor','interp');
plot(x, 1-y, 'linewidth', 2)
set(gca,'Xtick',[],'Ytick',[]); %Remove tick marks
Result:
Thank you Rotem! I wasn't aware of the patch function and indeed it solved the issue!
The colors on the actual figure I'm trying to achieve are not linear, so I just used patch for all the empty triangles. Here is the adjusted code I use for the simple example (again, this is just a bit more general just to be able to have non linear colors in the area above the curve):
x = linspace(0, 1, 10);
y = linspace(0, 1, 10);
z = linspace(0, 1, 10);
z = repmat(z, 10, 1)+0.1;
z = flipud(triu(z));
z(z==0) = nan;
z = z-0.1;
hold off
surf(x, y, z, 'linestyle', 'none')
colormap([linspace(0.39, 1, 20)',linspace(0.58, 0.25, 20)', linspace(0.93, 0.25, 20)']);
colorbar
xlim([x(1) x(end)])
shading interp
view([90 -90])
hold on
patch_cor_y = kron((length(y):-1:1)', ones(3, 1));
patch_cor_x = kron((1:length(x))', ones(3, 1));
patch_cor = [y(patch_cor_y(2:end-2))', x(patch_cor_x(3:end-1))'];
patch_path = reshape(1:length(patch_cor),3, length(patch_cor)/3)';
patch_col = z(sub2ind(size(z), patch_cor_x(3:end-1), patch_cor_y(2:end-2)));
patch('Faces',patch_path,'Vertices',patch_cor,'FaceVertexCData',patch_col,'FaceColor','interp', 'EdgeColor', 'none');
plot(x, 1-y, 'linewidth', 2)
The figure achieved: figure
I have to plot 5 lines that overlap in some regions, and I need to be able to see all the lines.
I can think of shifting the lines a bit to allow them to be displayed, but this doesn't seem a very elegante solution. Even so, how could I code such a thing?
Is there any other way to plot multiple overlapping lines while being able to distinguish them at every point?
For exemple, here is one exemple with 3 overlapping lines:
Thank you in advance!
Another way is to use transparency.
Unfortunatelly, line objects do not obey
transparency commands :(
A workaround is to:
1. download patchline (<-- link to Matlab Central)
2. use it to plot patchline with transparency
Once you have patchline, you can try something like:
% create some lines:
l1 = [1, 1, 1, 0, 0, 0.25, 1, 1, 0, 0, 0, 0, 1 1];
l2 = [0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1];
l3 = [1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0];
% plot with patchline (notice the use of 'EdgeAlpha'):
figure;
patchline(1:length(l1), l1, [], 'EdgeColor', [0.8, 0.2, 0.35],...
'LineWidth', 5, 'EdgeAlpha', 0.5 );
hold on;
patchline(1:length(l1), l2, 'EdgeColor', [0.2, 0.7, 0.55],...
'LineWidth', 5, 'EdgeAlpha', 0.5 );
patchline(1:length(l1), l3, 'EdgeColor', [0.1, 0.2, 0.95],...
'LineWidth', 5, 'EdgeAlpha', 0.5);
% change y limits to see line overlap clearly
set(gca, 'YLim', [-0.5, 1.5]);
Not an ideal way to do it - the rough 'cracks' will stay this way,
but you can experiment with different line widths or moving the
lines in y axis by a value that would correspond to an image with each
line covering only half of it closest neighbour...
You may play with EraseMode property of the plot line. The following code example shows how to shift the lines and EraseMode effect:
% First we generate some data
NLines = 2;
NPoints = 50;
LineWidth = 3;
ShiftStep = 1.1;
XData = linspace(0,1,NPoints);
YData = rand(NPoints,NLines);
for k=1:NLines
YData(:,k) = YData(:,k) > (k/(NLines+1));
end
% Then we create plot
figure('color','w');
subplot(3,1,1); plot(XData,YData, 'LineWidth',LineWidth);
ylim([-0.1 1.1]);
title('simple')
subplot(3,1,2); plot(XData,YData+repmat((0:NLines-1)*ShiftStep,NPoints,1), 'LineWidth',LineWidth, 'EraseMode','xor');
ylim([-0.1 1.1+ShiftStep*(NLines-1)]);
title('Shifted vertically')
subplot(3,1,3); plot(XData,YData, 'LineWidth',LineWidth, 'EraseMode','xor');
ylim([-0.1 1.1]);
title('EraseMode = xor')
In my opinion if you have more than three lines similar to your plot, shifting is visually more attractive. Also you may create several axes (Like I did) and plot each line in its own axes, so they will have y-labels set accordingly, but their X-labels will be essentially the same.
You can use plot3 and assign different Z values to different overlapping lines. However, it'll look more like you expect (Z being the "up" direction) if you swap the Y and Z axes:
Example:
Y1 = randn(1,100);
Y2 = randn(1,100);
X = 1:100;
Z1 = 1*ones(size(X));
Z2 = 2*ones(size(X));
plot3(X,Z1,Y1);
hold on;
plot3(X,Z2,Y2);