Can you have lines between circles on a scatter plot?

I am plotting two sets of data onto one plot, and I would like to have lines drawn connecting the different plots when they have the same value.

For a overly simple example:

a = [50:199];
b = [75:224];
i = [1:150];
scatter( i, [a;b] )

I would like a straight line joining dots together than have value 75, a line joining dots that have value 76, etc etc. Ideally the lines would be a different colour to the dots, but they themselves can be the same colour.

(I know in this example it would create a rather unhelpful-looking plot, but as said, this is much simpler than the types of scatters I'm looking at).

I'm quite new to Matlab, so I'm not sure whether this is something that's ridiculously easy or rather complex!

Answer 1

[Star Strider]

Try this —

a = [50:199];
b = [75:224];
i = [1:150];
scatter( i, [a;b] )
[ia,ib] = (ismember(a,b));
aidx = find(ia);
hold on
plot([i(aidx); i(ib(aidx))], ([1; 1]*a(aidx)), '-g', 'LineWidth',0.5)
hold off

The ismember call finds the elements common to both vectors. The rest is just addressing the correct elements of both of them, and plotting the horizontal lines.

.

[Josh Coyston]

This is what I was after - thank you! Certainly not something I'd've been able to come up with with my limited MATLAB knowledge!

[Star Strider]

As always, my pleasure!

It was something of a challenge for me as well. The ismember call was straightforward, however getting the indexing correct and then plotting the matrices correctly required some experimentation.