Subplot problems in matlab

Question

I am working on a problem in matlab where I am asked to plot an age distribution for 100 years, requiring 100 plots. I am looking to create 5 separate plots with 20 subplots in each for a total of 100. I can't seem to get past the first 20 plots without getting an error in my subplot command.

Here is the initial part of the code:

>> %initial age distribution
x0=[10;10;10];
%projection matrix
M=[0 4 3; 0.6 0 0; 0 0.25 0];

%calculate the total population size and age distribution for the first 100     years
X=zeros(3, 100);
X(:,1) = x0;
for kk = 2:100
X(:,kk) = M*X(:,kk-1);
end

%we need to double the population to account for males, assuming that   population is ½ males and ½ females

X=2*X

My initial plan was to create a 10x10 subplot but it looks awful, but this is the code I generated.

for ii = 1:100
subplot(10,10,ii)
set(gca,'FontSize',12)
barh(log10(X(:,ii)));
set(gca,'YTickLabel',{'Y1' 'Y2' 'Y3'})
xlabel('log(popn.)')
title(['Y' ,num2str(ii)])
axis([-1 25 0.5 3.5])
end

So i decided to do it in chunks of 20.

Here's what I have:

for ii = 1:20
subplot(5,4,ii)
set(gca,'FontSize',12)
barh(log10(X(:,ii)));
set(gca,'YTickLabel',{'Y1' 'Y2' 'Y3'})
xlabel('log10(population)')
title(['Y' ,num2str(ii)])
axis([-1 25 0.5 3.5])
end

When I try from 21 to 40, I get an error as follows:

for ii = 21:40
subplot(5,4,ii)
set(gca,'FontSize',12)
barh(log10(X(:,ii)));
set(gca,'YTickLabel',{'Y1' 'Y2' 'Y3'})
xlabel('log10(population)')
title(['Y' ,num2str(ii)])
axis([-1 25 0.5 3.5])
end
Error using subplot (line 280)
Index exceeds number of subplots.

I need to repeat for 21-40, 41-60, 61-80, and 81-100. Any help would be greatly appreciated. I am new to matlab.

Thanks!

When you use subplot(a, b, idx) you have idx available in the range [1 a*b] where a is the number of rows and b is the number of columns within the figure. — DreamBig

neerad29 neerad29 · Accepted Answer · 2016-02-24T20:48:29

The third argument in subplot can't exceed the total number of subplots. For example, when you use subplot(5, 4, ...), it means that there will be a total of 5*4 = 20 subplots, so the third argument can't be 21.

So you need to create a new figure using the figure command, and then create the next 20 subplots. In the end, you will have 5 different figures.

So your code will look something like this:

figure(1);    % First figure window
for ii = 1:20
    subplot(5,4,ii)    % create first 20 subplots
    set(gca,'FontSize',12)
    barh(log10(X(:,ii)));
    set(gca,'YTickLabel',{'Y1' 'Y2' 'Y3'})
    xlabel('log10(population)')
    title(['Y' ,num2str(ii)])
    axis([-1 25 0.5 3.5])
end
figure(2);    % second figure window
for ii = 21:40
    subplot(5,4,ii-20)    % create next 20 subplots
    set(gca,'FontSize',12)
    barh(log10(X(:,ii)));
    set(gca,'YTickLabel',{'Y1' 'Y2' 'Y3'})
    xlabel('log10(population)')
    title(['Y' ,num2str(ii)])
    axis([-1 25 0.5 3.5])
end
...

Subplot problems in matlab

2 Answers