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How to make multiple graphs with varying x-axis?

I need to plot multiple graphs in the same y-axis, but the x-axis is a bit tricky for me:

Assuming it goes from 0 to a, increasing by one, it needs to have an overall of a-1 different intervals.

Each one of them should finish at a, but it also has to have a different initialisation point. Only the first starts at 0, while each next one, starts by the previous plus one, as in the shape below. The two dashed lines, I used to visualise my thoughts as clear as I could, are not necessary.

I would appreciate any help!

enter image description here

Solution

  • Replicate your original interval 0 ... a a times (from my understanding, you'll have a intervals, not a-1), such that you get a matrix X of size [a x a+1]. Set the lower left triangle of X to NaN, so that the rows now represent your (shortening) intervals. Do your calculations on X. Pay attention, these have to support/neglect NaN values properly.

    After that, you need to adjust the values in X properly, so that the intervals are plotted subsequently. Basically, we add some fixed value to each row.

    Last, we need the proper xticks and xticklabels. Therefore, we extract all values from X and the modified X and get rid of the NaN values.

    Here's a complete code snippet:

    % Parameter
a = 7;

% Initialize intervals
X = repmat(0:a, a, 1);
X = X .* (ones(size(X)) + tril(nan(size(X)), -1));

% Calculation on these intervals; attention: there are NaN in X
Y = sin(X / a * 2 * pi);

% Modify X for plotting
X_plot = X;
X_plot(2:end, :) = X_plot(2:end, :) + cumsum(a:-1:2).';

% Get xticks
xt = X_plot.';
xt = xt(:);
xt(isnan(xt)) = [];

% Get xticklabels
xtl = X.';
xtl = xtl(:);
xtl(isnan(xtl)) = [];

% Plot
plot(X_plot.', Y.');
xticks(xt);
xticklabels(xtl);

    The output (Octave 5.1.0, also tested with MATLAB Online) looks like this:

    Output

    If you only want for example the start and end of each interval, you must further pre-process xt and xtl.

    Hope that helps!