Subplots in a single "axes" object

I want to plot 4 graphs using subplot function with 2 x-axes---one on buttom (frequency)---another on top (Strouhal no). I have written following program for that but it is plotting all graphs in same subplot.

Please suggest.

Thank you in advance.

load('data.mat');

figure(1)
ax = axes();
hold(ax);

Current plot held

ax.YAxis.Scale = 'log';
ax.XAxis.Scale = 'log';
%xlabel(ax, 'Frequency (Hz)', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
%ylabel(ax, 'Power spectral density', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
grid on

% setup top axis
ax_top = axes(); % axis to appear at top
hold(ax_top);

Current plot held

ax_top.XAxis.Scale = 'log';
ax_top.XAxisLocation = 'top';
ax_top.YAxisLocation = "right";
ax_top.YTick = [];
% ax_top.XDir = 'reverse';
ax_top.Color = 'none';
%xlabel(ax_top, 'Strouhal number', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
% linking axis
linkprop([ax, ax_top],{'Units','Position','ActivePositionProperty'});
%ax.Position(1,1) = ax.Position(1);
v = 4.687276290832519e+02*12; % inches/sec
c = 16; % inches
f=[0.25 0.5 1 2 4 6 10 16 30 50 100 200 500];
st = f*c./v; % Strouhal number
% configure limits of bottom axis
ax.XLim = [f(1) f(end)];
ax.XTick = f;
ax.XAxis.MinorTick = 'on';
% configure limits and labels of top axis
ax_top.XLim = [st(1) st(end)];

subplot(2,2,1,ax)
plot(fCompnnts(1:end/2),psd3(1:end/2))
subtitle('$x/c=0.448$','Interpreter','latex')

subplot(2,2,2,ax)
plot(fCompnnts(1:end/2),psd4(1:end/2))
subtitle('$x/c=0.498$','Interpreter','latex')

subplot(2,2,3,ax)
plot(fCompnnts(1:end/2),psd5(1:end/2))
subtitle('$x/c=0.542$','Interpreter','latex')

subplot(2,2,4,ax)
plot(fCompnnts(1:end/2),psd8(1:end/2),'-h','Color',[0.6350 0.0780 0.1840])
subtitle('$x/c=0.950$','Interpreter','latex')

Answer 1

[Cris LaPierre]

I think you might find this answer helpful: https://www.mathworks.com/matlabcentral/answers/477222-copy-a-figure-to-a-subplot-including-all-elements#answer_388666

I think the issue is that, in your code, ax always refers to the same axes, not a copy of the template axes you created. Because of that, you keep moving the axes around, with it ending in the final spot with all plots in it.

Instead, you want to create a copy of the axes object in each subplot location, which is what the linked answer does. It's not quite the elegant solution you might expect or want, but it works.

load('data.mat');

figure(1)
ax = axes();
hold(ax);
ax.YAxis.Scale = 'log';
ax.XAxis.Scale = 'log';
%xlabel(ax, 'Frequency (Hz)', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
%ylabel(ax, 'Power spectral density', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
grid on

% setup top axis
ax_top = axes(); % axis to appear at top
hold(ax_top);
ax_top.XAxis.Scale = 'log';
ax_top.XAxisLocation = 'top';
ax_top.YAxisLocation = "right";
ax_top.YTick = [];
% ax_top.XDir = 'reverse';
ax_top.Color = 'none';
%xlabel(ax_top, 'Strouhal number', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
% linking axis
linkprop([ax, ax_top],{'Units','Position','ActivePositionProperty'});
%ax.Position(1,1) = ax.Position(1);
v = 4.687276290832519e+02*12; % inches/sec
c = 16; % inches
f=[0.25 0.5 1 2 4 6 10 16 30 50 100 200 500];
st = f*c./v; % Strouhal number
% configure limits of bottom axis
ax.XLim = [f(1) f(end)];
ax.XTick = f;
ax.XAxis.MinorTick = 'on';
% configure limits and labels of top axis
ax_top.XLim = [st(1) st(end)];

% Updated code
fig2 = figure(2);
ax1 = subplot(2,2,1,'parent',fig2);
ax2 = subplot(2,2,2,'parent',fig2);
ax3 = subplot(2,2,3,'parent',fig2);
ax4 = subplot(2,2,4,'parent',fig2);

axcp1 = copyobj(ax, fig2);
set(axcp1,'Position',get(ax1,'position'));
delete(ax1);
plot(axcp1,fCompnnts(1:end/2),psd3(1:end/2))
title(axcp1,'$x/c=0.448$','Interpreter','latex')

axcp2 = copyobj(ax, fig2);
set(axcp2,'Position',get(ax2,'position'));
delete(ax2);
plot(axcp2,fCompnnts(1:(end)/2),psd4(1:end/2))
title(axcp2,'$x/c=0.498$','Interpreter','latex')

axcp3 = copyobj(ax, fig2);
set(axcp3,'Position',get(ax3,'position'));
delete(ax3);
plot(axcp3,fCompnnts(1:end/2),psd5(1:end/2))
title(axcp3,'$x/c=0.542$','Interpreter','latex')

axcp4 = copyobj(ax, fig2);
set(axcp4,'Position',get(ax4,'position'));
delete(ax4);
plot(axcp4,fCompnnts(1:end/2),psd8(1:end/2),'-h','Color',[0.6350 0.0780 0.1840])
title(axcp4,'$x/c=0.950$','Interpreter','latex')

I get an error when trying to run that code here, but it works in R2022a at least. Here is the result

[MAGAN SINGH]

Hello @Cris LaPierre

Thank you for your quick responce and suggestion.

I defined "ax" axis for having bottom (frequency) and top (Strouhal no) axis in a plot. This works fine for all graphs in a single plot, means shows both axis with linked tick values. But, I am not seeing top axis in your answer. Can you look into it?

Magan

[Cris LaPierre]

Ah, it's only copying the one axes. To be honest, I would code this differently. Rather than trying to create a template axes and copy it into each location in subplot, I would plot into each subplot and then use a custom function to format the plot.

load('data.mat');

ax1 = subplot(2,2,1);
plot(fCompnnts(1:end/2),psd3(1:end/2))
title('$x/c=0.448$','Interpreter','latex')
formatAxis(ax1)

ax2 = subplot(2,2,2);
plot(fCompnnts(1:(end)/2),psd4(1:end/2))
title('$x/c=0.498$','Interpreter','latex')
formatAxis(ax2)

ax3 = subplot(2,2,3);
plot(fCompnnts(1:end/2),psd5(1:end/2))
title('$x/c=0.542$','Interpreter','latex')
formatAxis(ax3)

ax4 = subplot(2,2,4);
plot(fCompnnts(1:end/2),psd8(1:end/2),'-h','Color',[0.6350 0.0780 0.1840])
title('$x/c=0.950$','Interpreter','latex')
formatAxis(ax4)

function formatAxis(ax)
ax.YAxis.Scale = 'log';
ax.XAxis.Scale = 'log';
%xlabel(ax, 'Frequency (Hz)', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
%ylabel(ax, 'Power spectral density', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
grid on

% setup top axis
ax_top = axes(); % axis to appear at top
ax_top.XAxis.Scale = 'log';
ax_top.XAxisLocation = 'top';
ax_top.YAxisLocation = "right";
ax_top.YTick = [];
% ax_top.XDir = 'reverse';
ax_top.Color = 'none';
%xlabel(ax_top, 'Strouhal number', 'Interpreter', 'latex', 'FontSize', 14,'FontWeight','Bold');
% linking axis
linkprop([ax, ax_top],{'Units','Position','ActivePositionProperty'});
%ax.Position(1,1) = ax.Position(1);
v = 4.687276290832519e+02*12; % inches/sec
c = 16; % inches
f=[0.25 0.5 1 2 4 6 10 16 30 50 100 200 500];
st = f*c./v; % Strouhal number
% configure limits of bottom axis
ax.XLim = [f(1) f(end)];
ax.XTick = f;
ax.XAxis.MinorTick = 'on';
% configure limits and labels of top axis
ax_top.XLim = [st(1) st(end)];
end

As you can see, the title and top xaxes are overlapping. See this Answer for help with this. The fix could be to add another (empty) line to your title:

title({'$x/c=0.448$';''},'Interpreter','latex')

The result looks like this:

[MAGAN SINGH]

Thank you @Cris LaPierre