plotting functions with two y axes

2025 1 19
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更新时间：2025 1 23
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Hello,
I have to plot two curves on the same graph, same x-axis and different y-axes (right and left). I can't draw the curves with different hatching, different thickness and same black color. I would also like to insert the title of the axes and the legend. Below is the attempt script (R2021b).
Many thanks for the help
figure(1)
x1 = 0:0.1:10;
y1=10+x1.*4;
x2 = 0:0.1:10;
y2=15*sin(x2/2)
t = tiledlayout(1,1);
ax1 = axes(t);
plot(ax1,x1,y1,'-k')
ax1.XColor = 'k';
ax1.YColor = 'k';
ax2 = axes(t);
plot(ax2,x2,y2,'--k')
ax1.XAxisLocation = 'bottom';
ax1.YAxisLocation = 'left';
ax2.XAxisLocation = 'top';
ax2.YAxisLocation = 'right';
ax2.Color = 'none';
ax1.Box = 'off';
ax2.Box = 'off';
grid

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 采纳的回答

Star Strider
Star Strider 2025-1-19
编辑：Star Strider 2025-1-19
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0 个投票

Ran in:
Use the yyaxis function. It should work with tiledlayout axes.
EDIT — (19 Jan 2025 at 16:10)
I am not certain what result you want, however your code otherwise works as posted.
Try this —
figure(1)
x1 = 0:0.1:10;
y1=10+x1.*4;
x2 = 0:0.1:10;
y2=15*sin(x2/2)
y2 = 1×101
0 0.7497 1.4975 2.2416 2.9800 3.7111 4.4328 5.1435 5.8413 6.5245 7.1914 7.8403 8.4696 9.0778 9.6633 10.2246 10.7603 11.2692 11.7499 12.2012 12.6221 13.0113 13.3681 13.6915 13.9806 14.2348 14.4534 14.6359 14.7817 14.8907
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
t = tiledlayout(1,1);
ax1 = axes(t);
hp(1) = plot(ax1,x1,y1,'-k', DisplayName="(x_1, y_1)");
ax1.XColor = 'k';
ax1.YColor = 'k';
ax2 = axes(t);
hp(2) = plot(ax2,x2,y2,'--k', DisplayName="(x_2, y_2)");
ax1.XAxisLocation = 'bottom';
ax1.YAxisLocation = 'left';
ax2.XAxisLocation = 'top';
ax2.YAxisLocation = 'right';
ax2.Color = 'none';
ax1.Box = 'off';
ax2.Box = 'off';
grid
xlabel(ax1, 'x_1, x_2')
ylabel(ax1, 'y_1')
ylabel(ax2, 'y_2')
title("Your Title Goes Here")
legend([hp], Location='best')
●
I made some minor changes, however I kept your original code.
.

更多回答（3 个）

Andrea
Andrea 2025-1-19

0 个投票

dear Star Strider,
thank you very much, it works perfectly
Andrea
Andrea
Andrea 2025-1-22

0 个投票

dear all,
I would like to plot multiple curves on the same graph using two y-axes. With your help I managed to plot two curves but I would need to add two more curves on the same axes, for a total of four curves.
I drew the third curve using the traditional “plot” command after the hold on command, if I add the equation of the fourth curve the scale of the y-axis changes compared to that of the current listing. I would like to keep the current scale.
Below is the equation of the curve that I would like to add: x4 = 0:0.1:0.6; y4 = -250.*x1+150. I would also like to add these two curves to the legend. I am adding the current listing.
figure(1) % new figure
x1 = 0:0.1:0.6;
y1 = -500.*x1+300;
x2 = 0:0.1:0.6;
y2 = 29.33.*x2;
x3 = 0:0.1:0.6;
y3 = 14.66.*x2;
x4 = 0:0.1:0.6;
y4 = -250.*x1+150;
t = tiledlayout(1,1);
ax1 = axes(t);
ax2 = axes(t);
hp(1) = plot(ax1,x1,y1,'--k', 'linewidth',1,DisplayName="(x_1, y_1)");
ax1.XColor = 'k';
ax1.YColor = 'k';
%ax3 = axes(t);
hp(2) = plot(ax2,x2,y2,'--k', 'linewidth',2,DisplayName="(x_2, y_2)");
% hp(3) = plot(ax2,x3,y3,'-k', 'linewidth',1,DisplayName="(x_3, y_3)");
% hp(4) = plot(ax2,x4,y4,'-k', 'linewidth',1,DisplayName="(x_4, y_4)");
ax1.XAxisLocation = 'bottom';
ax1.YAxisLocation = 'left';
%ax2.XAxisLocation = 'top';
ax2.YAxisLocation = 'right';
ax2.Color = 'none';
% ax3.YAxisLocation = 'none';
% ax3.Color = 'none';
ax1.Box = 'off';
ax2.Box = 'off';
% ax3.Box = 'off';
grid
xlabel(ax1, 'x1')
ylabel(ax1, 'y1')
ylabel(ax2, 'y2')
%title("Your Title Goes Here")
legend([hp], Location='best')
%legend([hp])
hold on
plot(x3,y3,'-k', 'linewidth',2)
%plot(x4,y4,'-k', 'linewidth',2)
Thanks for your help!
Andrea

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Star Strider
Star Strider 2025-1-22
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Ran in:
It’s difficultt for me to figure out what you¹re doing. That aside, I cannot get the added curve (X4,y4) to work with it.
I went a compleetely different route and used the yyaxis function here —
figure(1) % new figure
x1 = 0:0.1:0.6;
y1 = -500.*x1+300;
x2 = 0:0.1:0.6;
y2 = 29.33.*x2;
x3 = 0:0.1:0.6;
y3 = 14.66.*x2;
x4 = 0:0.1:0.6;
y4 = -250.*x1+150;
% t = tiledlayout(1,1);
% ax1 = axes(t);
% ax2 = axes(t);
% hp(1) = plot(ax1,x1,y1,'--k', 'linewidth',1,DisplayName="(x_1, y_1)");
% % hp(3) = plot(ax1, x4, y4, '-.k', DisplayName='(X_4, y_4)');
% ax1.XColor = 'k';
% ax1.YColor = 'k';
% %ax3 = axes(t);
% hp(2) = plot(ax2,x2,y2,'--k', 'linewidth',2,DisplayName="(x_2, y_2)");
% % hp(3) = plot(ax2,x3,y3,'-k', 'linewidth',1,DisplayName="(x_3, y_3)");
% % hp(4) = plot(ax2,x4,y4,'-k', 'linewidth',1,DisplayName="(x_4, y_4)");
% hp(3) = plot(ax1, x4, y4, '-.k', DisplayName='(X_4, y_4)');
% ax1.XAxisLocation = 'bottom';
% ax1.YAxisLocation = 'left';
% %ax2.XAxisLocation = 'top';
% ax2.YAxisLocation = 'right';
% ax2.Color = 'none';
% % ax3.YAxisLocation = 'none';
% % ax3.Color = 'none';
% ax1.Box = 'off';
% ax2.Box = 'off';
% % ax3.Box = 'off';
% grid
% xlabel(ax1, 'x1')
% ylabel(ax1, 'y1')
% ylabel(ax2, 'y2')
% hp
% %title("Your Title Goes Here")
% % legend([hp], Location='best')
% % legend([hp])
% hold on
% plot(x3,y3,'-k', 'linewidth',2)
% %plot(x4,y4,'-k', 'linewidth',2)
figure
yyaxis left
hp(1) = plot(x1,y1,'--k', 'linewidth',1,DisplayName="(x_1, y_1)");
hold on
hp(2) = plot(x2,y2,'--k', 'linewidth',2,DisplayName="(x_2, y_2)");
hold off
yyaxis right
hp(3) = plot(x3,y3,'-k', 'linewidth',1,DisplayName="(x_3, y_3)");
hold on
hp(4) = plot(x4,y4,'-k', 'linewidth',1,DisplayName="(x_4, y_4)");
hold off
grid
legend([hp], Location='best')
●
Make appropriate changes to get your desired result.
.

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Andrea
Andrea 2025-1-23

0 个投票

Dear Star Strider,
thank you very much for your help, by slightly modifying your script I got the graph I needed. I just can't write the names of the x, y1 and y2 axes. Here the script. Thank you!
Andrea
figure(2)
x1 = 0:0.1:0.6;
y1 = -500.*x1+300;
x2 = 0:0.1:0.6;
y2 = 29.8.*x2;
x3 = 0:0.1:0.6;
y3 = 14.9.*x2;
x4 = 0:0.1:0.6;
y4 = -250.*x1+150;
yyaxis left
hp(4) = plot(x4,y4,'-k', 'linewidth',1,DisplayName="F_1");
hold on
hp(1) = plot(x1,y1,'-k', 'linewidth',2,DisplayName="F_2");
hold on
%hold off
yyaxis right
hp(2) = plot(x2,y2,'--k', 'linewidth',2,DisplayName="P_1");
hp(3) = plot(x3,y3,'--k', 'linewidth',1,DisplayName="P_2");
%hold on
hold off
grid
legend([hp], Location='best')

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Star Strider
Star Strider 2025-1-23
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Ran in:
As always, my pleasure!
You can refer to the ylabel calls by using their appropriate axis references, however it is easiest to just put them in the appropriate parts of the code, as I do here.
Try this —
figure(2)
x1 = 0:0.1:0.6;
y1 = -500.*x1+300;
x2 = 0:0.1:0.6;
y2 = 29.8.*x2;
x3 = 0:0.1:0.6;
y3 = 14.9.*x2;
x4 = 0:0.1:0.6;
y4 = -250.*x1+150;
yyaxis left
hp(4) = plot(x4,y4,'-k', 'linewidth',1,DisplayName="F_1");
hold on
hp(1) = plot(x1,y1,'-k', 'linewidth',2,DisplayName="F_2");
hold on
%hold off
ylabel('Left Y-Axis', FontWeight='bold')
yyaxis right
hp(2) = plot(x2,y2,'--k', 'linewidth',2,DisplayName="P_1");
hp(3) = plot(x3,y3,'--k', 'linewidth',1,DisplayName="P_2");
%hold on
hold off
grid
ylabel('Right Y-Axis', FontWeight='bold')
% legend([hp], Location='best')
legend([hp], Location='N')
●
Also, since legend does not appear to be sensitive to the plots on both axes, I put it manually where it wiill not cover any parts of the llines.
.

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