Can I specify the color of a graphics object by its index in the ColorOrder?

Specifying colors of graphics objects by characters is most convenient, like in

plot([1 2],'r--')

Is there a similar way to select colors by their index in the ColorOrder? That is, I am looking for something like

plot([1 2],'2--')

as an abbreviation for

c = get(gca,'ColorOrder');

plot([1 2],'--','Color',c(2,:))

If not (as I assume) it would be really great to have that in a future release.

[DGM]

FWIW, you could also manipulate the index directly before calling plot()

set(gca,'ColorOrderIndex',2); hold on;
plot([2 1],'--','linewidth',2); % i made it thicker so it's more visible

... but that's not really any more convenient, and the quirks with the changes circa R2019b might make the exact usage version-dependent to some degree. I wouldn't consider it a valid answer, but maybe it's worth a comment.

EDIT:

I suppose it's worth noting that the default color table is lines(7) (both pre- and post-R2014b), so this:

c = get(gca,'ColorOrder');

should be the same as this (unless you set it to something other than the default)

c = lines(7);

though again, that doesn't really simplify anything either.

Unless someone comes up with a brilliant solution, I think it's worth making a feature request. Off the top of my head, I don't see any obvious snags with the proposed color/style string format.

[Stephen23]

@DGM: you should move this comment to an answer. It is much closer to answering the question, and would get a vote from me.

[Steven Lord]

" Off the top of my head, I don't see any obvious snags with the proposed color/style string format."

What should this code plot?

plot(1:10, 1:10, '2')

Should this plot the line using the second color in the ColorOrder property of the axes?

Should this plot the line using the second line style in the LineStyleOrder property of the axes?

Should this plot the line using both the second element of ColorOrder and the second element of LineStyleOrder?

Why should color take precedence over line style?

What if I wanted to use the third color and the second line style? What would the syntax for that statement be using this indexed approach?

[DGM]

oof. Yeah I guess that's pretty obvious. To be fair, the view from the top of my head barely clears the hedgerow.

[Steven Lord]

To be equally fair I've had a lot of practice coming up with questions like that about proposed designs for functions and functionality to try to expose assumptions and ambiguities in the design. Design reviews are an important part of our core values and I've participated in more than my fair share of reviews in the past 20 years.

[Ulrich Reif]

Steven,

your argument doesn't convince me. Using the string argument I can easily define all possible linestyles, but I cannot access the current color palette. This would be so helpful, for instance when a line and the corresponding text annotation should appear in the same color. At least, you could think about allowing the pairing plot(...,'Color',index) to serve that purpose.

.

[DGM]

Then let me ask your opinion on what might be an alternative. Given that the flexibility of the simplified syntax for plot() would lead to ambiguities if trying to basically cram another parameter into the string, what about using the new colororder() function? Would it be possible/practical/more elegant to provide an unambiguous means of directly addressing in a call to colororder()?

Something like

secondtuple = colororder(axishandle,2);

or something similar that would allow colororder() to be used inline?

plot(mydata,'--','Color',colororder(gca,2))

Or would there be a better way other than just pulling the color table in a separate line?

[Stephen23]

I second this proposed syntax:

plot(..,'Color',index)

Answer 1

[Wan Ji]

If you want different colors, you can use matlab build-in color series like jet, hsv, bone, copper. Eaxmples are

n = 1:6;
color = jet(length(n));
x = 0:0.1:7;
hold on
a = arrayfun(@(i)plot(x,gampdf(x,n(i)),'color',color(i,:)), 1:length(n));
legend(arrayfun(@(i)['\Gamma(',num2str(n(i)),',1)'],1:1:length(n),'uniform',false))

You can also use random colors

n = 1:6;
color = rand(length(n),3);
x = 0:0.1:7;
hold on
a = arrayfun(@(i)plot(x,gampdf(x,n(i)),'color',color(i,:)), 1:length(n));
legend(arrayfun(@(i)['\Gamma(',num2str(n(i)),',1)'],1:1:length(n),'uniform',false))

Actually, color in matlab is a 1x3 array with interval [0,1]

[DGM]

OP wasn't asking how to assign a new color table to the 'colororder' property, but rather if there were a convenient method to specify a color by its index within the existing colortable set in 'colororder' -- whatever colortable that might be.

I think it's a pretty good question.

[Ulrich Reif]

Exactly!

[Wan Ji]

how many colors there are! I dont think this idea is brilliant. Just use the existing colors or color tables are enough to tell people the differences of all the curves.

[Stephen23]

"how many colors there are!"

Seven.

"Just use the existing colors"

The line ColorOrder are existing colors:

https://www.mathworks.com/help/matlab/creating_plots/defining-the-color-of-lines-for-plotting.html

https://www.mathworks.com/help/releases/R2019a/matlab/graphics_transition/why-are-plot-lines-different-colors.html

Answer 2

[Image Analyst]

See my attached demo that shows you how to change the default color order:

The demo allows you to pick from the set of 20 or so built-in colormaps (I used jet in the demo above), though you could of course define your own custom colors. Adapt as needed.

[DGM]

OP wasn't asking how to assign a new color table to the 'colororder' property, but rather if there were a more convenient method to specify a color by its index within the existing colortable set in 'colororder' -- whatever colortable that might be at the time.