different symbols with different colors in a same legend

I would like to use a single legend line for symbols of different colors.

For example, something like below would put two circle symbols of different colors in the same line followed by the texts:

legend = '{\color{blue}O} {\color{green}O} legend1'

How do I do that in a plot legend in a general way?

The example given in the link below allows multiple symbols on the same line, but there doesn't seem to be a way to assign different colors.

https://www.mathworks.com/matlabcentral/answers/509606-how-to-merge-two-legend-in-one#answer_811453

Answer 1

[Walter Roberson]

There isn't any way to do that with legend()

You might want to start with https://www.mathworks.com/matlabcentral/fileexchange/31092-legendflex-m-a-more-flexible-customizable-legend and customize the code

[Zhong Chen]

Thanks for the answer. I think I may just do a text box using LaTex, or post process the graph in Inkscape.