Shade the encircled area

1 次查看（过去 30 天）
Muhammad Sanwal
Muhammad Sanwal 2020-8-29
评论： Star Strider 2020-9-2
Hi. Can anyone please tell me how to shade the encircled area(in red)?
The graph is as follows
And the code is as follows
tx1=-7:0.1:-1;
tx2=-1:0.1:0.5;
tx3=0.5:0.1:3;
tx4=3:0.1:7;
tx=[tx1 tx2 tx3 tx4];
x1=zeros(size(tx1));
x2=0.6.*ones(size(tx2));
x3=0.3.*ones(size(tx3));
x4=zeros(size(tx4));
x=[x1 x2 x3 x4];
th1=-7:0.1:0;
th2=0:0.1:7;
h1=zeros(size(th1));
h2=ones(size(th2));
h3=[h1 h2];
th=[th1 th2];
h4=exp(-th);
h=h3.*h4;
t=0;
plot(tx,x,-th+t,h,'-','linewidth',2)
ylim([-0.1 1.1])
legend('x(\tau)','h(t-\tau)')
grid

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2020-8-30
After the original code in your Question (not your subsequent Comment), add these lines:
hold on
Ltx = (tx >= -1) & (tx <= 0);
Ltht = (-th+t >= -1) & (-th+t <= 0);
xh = min([x(Ltx); h(Ltht)]);
patch([tx(Ltx) flip(tx(Ltx))], [zeros(size(xh)) xh], 'g')
hold off
to get this plot:
.
  9 个评论
显示 7更早的评论
Star Strider
Star Strider 2020-9-2
As always, my pleasure!

请先登录，再进行评论。

更多回答（3 个）

the cyclist
the cyclist 2020-8-30
Combining your new code that aligns the values of t (but not using your attempt at creating the patch), and the same basic idea of Star Strider and Image Analyst, this code accurately aligns the patch as I believe you want. But, as Star Strider says, you decide.
t1=-7:0.1:-1;
t2=-1:0.1:0;
t3=0:0.1:0.5;
t4=0.5:0.1:3;
t5=3:0.1:7;
t=[t1 t2 t3 t4 t5];
x1=zeros(size(t1));
x2=0.6.*ones(size(t2));
x3=0.6.*ones(size(t3));
x4=0.3.*ones(size(t4));
x5=zeros(size(t5));
x=[x1 x2 x3 x4 x5];
h1=zeros(size(t1));
h2=zeros(size(t2));
h3=ones(size(t3));
h4=ones(size(t4));
h5=ones(size(t5));
h6=[h1 h2 h3 h4 h5];
h7=exp(-t);
h=h6.*h7;
figure
hold on
plot(t,x,-t,h,'-','linewidth',2)
ylim([-0.1 1.1])
legend('x(\tau)','h(t-\tau)')
grid
lightGreen = [0.85, 1, 0.85];
xh = min([x; flip(h)]);
plot(t,xh)
patch([flip(t) t], [zeros(size(t)) xh], lightGreen)
  2 个评论
Muhammad Sanwal
Muhammad Sanwal 2020-8-30
both methods work. thanks!
the cyclist
the cyclist 2020-8-30
Glad it worked out. Be aware that the two solutions cover slightly different areas, and this is more evident with the relative large step size (0.1) you are using.
If you use something smaller (e.g. 0.01), both solutions will more sharply align with your lines, visually.

请先登录，再进行评论。

Bruno Luong
Bruno Luong 2020-8-30
编辑：Bruno Luong 2020-8-30
Use polyshape and let polyshape do the work. Replace plot(P1, ...) with normal plot if you don't like the artefact on x-axis.
t1=-7:0.1:-1;
t2=-1:0.1:0;
t3=0:0.1:0.5;
t4=0.5:0.1:3;
t5=3:0.1:7;
t=[t1 t2 t3 t4 t5];
x1=zeros(size(t1));
x2=0.6.*ones(size(t2));
x3=0.6.*ones(size(t3));
x4=0.3.*ones(size(t4));
x5=zeros(size(t5));
x=[x1 x2 x3 x4 x5];
h1=zeros(size(t1));
h2=zeros(size(t2));
h3=ones(size(t3));
h4=ones(size(t4));
h5=ones(size(t5));
h6=[h1 h2 h3 h4 h5];
h7=exp(-t);
h=h6.*h7;
warning('off','MATLAB:polyshape:repairedBySimplify');
P1=polyshape(t,x);
P2=polyshape(-t,h);
close all
figure
hold on
plot(P2,'facecolor','none','edgecolor','r','linewidth',1)
plot(P1,'facecolor','none','edgecolor','b','linewidth',1)
plot(intersect(P1,P2), 'Facecolor', [0.5, 1, 0.5],'linestyle','none');
ylim([-0.1 1.1])
legend('h(t-\tau)','x(\tau)','whatever')
grid
  2 个评论
Bruno Luong
Bruno Luong 2020-8-31
编辑：Bruno Luong 2020-8-31
Shift annimation:
t1=-7:0.1:-1;
t2=-1:0.1:0;
t3=0:0.1:0.5;
t4=0.5:0.1:3;
t5=3:0.1:7;
t=[t1 t2 t3 t4 t5];
x1=zeros(size(t1));
x2=0.6.*ones(size(t2));
x3=0.6.*ones(size(t3));
x4=0.3.*ones(size(t4));
x5=zeros(size(t5));
x=[x1 x2 x3 x4 x5];
h1=zeros(size(t1));
h2=zeros(size(t2));
h3=ones(size(t3));
h4=ones(size(t4));
h5=ones(size(t5));
h6=[h1 h2 h3 h4 h5];
h7=exp(-t);
h=h6.*h7;
warning('off','MATLAB:polyshape:repairedBySimplify');
close all
figure
for tau=0:0.1:4
cla
hold on
t1 = t;
t2 = tau-t;
P1=polyshape(t1,x);
P2=polyshape(t2,h);
plot(t1,x,'color','r','linewidth',1)
plot(t2,h,'color','b','linewidth',1)
plot(intersect(P1,P2), 'Facecolor', [0.5, 1, 0.5],'linestyle','none');
xlim([-6 12]);
ylim([-0.1 1.1])
legend('h(t-\tau)','x(\tau)','whatever')
grid on
drawnow
end
Muhammad Sanwal
Muhammad Sanwal 2020-9-2
Yes, this code works too. Thankyou!

请先登录，再进行评论。

Image Analyst
Image Analyst 2020-8-29
See the FAQ and adapt as needed.
FAQ How_do_I_shade_the_region_between_two_curves?
  2 个评论
the cyclist
the cyclist 2020-8-29
@muhammad:
Note that the solution that @ImageAnalyst posted makes this statement:
% Assume y1 and y2 have the same number of elements located at the same x values.
Your curves do not obey this assumption, which makes your problem significantly more difficult (I think).
If you can define data in a way that they use the same t (number of elements and same values), this will be an easier task.
Next best would be using at least the same number of elements (if not at the same values).
Muhammad Sanwal
Muhammad Sanwal 2020-8-30
I made my vector t of the same length, but the graph I get is as follows
Please help me make changes to the program so that I can get the original encircled area (in red), as mentioned in my question.
The code is as follows
t1=-7:0.1:-1;
t2=-1:0.1:0;
t3=0:0.1:0.5;
t4=0.5:0.1:3;
t5=3:0.1:7;
t=[t1 t2 t3 t4 t5];
x1=zeros(size(t1));
x2=0.6.*ones(size(t2));
x3=0.6.*ones(size(t3));
x4=0.3.*ones(size(t4));
x5=zeros(size(t5));
x=[x1 x2 x3 x4 x5];
h1=zeros(size(t1));
h2=zeros(size(t2));
h3=ones(size(t3));
h4=ones(size(t4));
h5=ones(size(t5));
h6=[h1 h2 h3 h4 h5];
h7=exp(-t);
h=h6.*h7;
plot(t,x,-t,h,'-','linewidth',2)
ylim([-0.1 1.1])
legend('x(\tau)','h(t-\tau)')
grid
% Shade the area between in light green using the patch() function.
lightGreen = [0.85, 1, 0.85];
% Create the boundaries of the upper points and the lower points.
% Assume x and h have the same number of elements located at the same x values.
upperBoundary = max(x, h);
lowerBoundary = min(x, h);
% Now do the actual display of the shaded region.
patch([t fliplr(t)], [upperBoundary fliplr(lowerBoundary)], lightGreen);
% Plot x and h AFTER the patch so the patch does not cover any of those curves.
hold on;
plot(t, x, 'r-', 'LineWidth', 2); % Plot curve 1 in red.
plot(t, h, 'b-', 'LineWidth', 2); % Plot curve 2 in blue.
legend('Patch', 'y1', 'y2');
% Maximize the figure window
g = gcf; % Setting the WindowState on gcf directly doesn't work for some reason.
g.WindowState = 'maximized'

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Graphics Performance 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by