如何确定Matlab中子图的尺寸？

Question

So I am writing a function that plots matrix data from n different cells. If n is 10, it should display 10 equally spaced plots on a single figure. If n is 7, it should try to space them out as equally as possible (so 3x2 or 2x3 plots with a plot by itself).

I am able to get these graphs drawn using subplot() and plot() but I'm having a hard time finding out how to initialise the dimensions for the subplot.

The number of subplots will be changing after each run so I can't initialise it to specific dimensions.

Can anyone point me in the right direction?

Answer 1

I am afraid problems like this tend to be messy. This normally problems like this need to be solved for different cases.

if (mod(n,2) && n<8)
    % Do something
elseif (!mod(n,2) && n < 11)
    % Do something else
elseif ...
    ....
end

The conditions are choosen a bit arbitarily since the specifications in the OP seemed a bit arbitary too. You probably understand the point and can set your own conditions.

There are two reasons why I recommend this approach.

1) This makes the code simpler to write. You do not have to come up with some complicated solution which may break in after some time.

2) By adding cases you can protect yourself against a rampant number of plots. In case the number of plots gets too large you do typically not want to have all plots in the same figure. It is also possible to wrap this into a function and apply this to X plots at a time in a loop. Typically you would want each iteration to be a separate figure.

It is not very easy to elaborate more on this since you have not yet specified how many cases you expect or what will happen to the last plot in case of odd numbers. Still this may give a good hint.

Good luck!

Answer 2

Another simple solution would be using round and ceil on the square root:

for n=1:20
    [n, round(sqrt(n))*ceil(sqrt(n)),  round(sqrt(n)), ceil(sqrt(n))]
end

output:

%(n, total_plots, x, y)
 1     1     1     1
 2     2     1     2
 3     4     2     2
 4     4     2     2
 5     6     2     3
 6     6     2     3
 7     9     3     3
 8     9     3     3
 9     9     3     3
10    12     3     4

Usage example:

n = 7
subplot(round(sqrt(n)), ceil(sqrt(n)), plot_nr_x) % switch first 2 params to have either a slightly longer or slightly wider subplot

Answer 3

I ran into a very similar problem today and I was having a lot of trouble to define the size of the subplot that would fit everything. My reasoning is mostly a hack but it can help. If you have to represent at most n figures, you can thing as a square grid of sqrt(n) * sqrt(n) . To make things better we add a safety row, so the final matrix would be (sqrt(n) + 1) * sqrt(n) . I hope this helps solving your problem.

In my code have 2 nested loops:

within a loop that opens a figure for each kk element and is meant to plot a particular graph from the x position within the array.

for kk=1:length(some_file_list)

      % Load data
      % do some math
      % get data as a cell array with things we care about in data(3,)

    array_size = size(data(3,:),2);

      for x=1:size(data(3,:),2);

    % do more math and get things ready to plot matrix_A scaled by range_A

            figure(kk); % open figure       
                grid_rows = round((sqrt(array_size)+1));
                grid_cols = round(sqrt(array_size));

                % plot
                subplot(grid_rows, grid_cols, x);
                imagesc(matrix_A,range_A); %plot in position
                colormap(gray);
         end
 end