legend NumColumns not working in 2018a

I'm using MATLAB 2018a, which I understand is when the NumColumns property of legend appeared. But when I run this code:

t = 2*pi*(0:0.01:1);
x1 = sin(t);
x2 = cos(t);

figure(1)
plot(t,x1)
hold %on
plot(t,x2)
hold %off
xlim([0 2*pi])
legend('sin(t)','cos(t)','NumColumns',2)

I receive these errors:

Error using legend>process_inputs (line 554)

Invalid argument. Type 'help legend' for more information.

Error in legend>make_legend (line 306)

[autoupdate,orient,location,position,children,listen,strings,propargs] = process_inputs(ha,argin);

%#ok

Error in legend (line 259)

make_legend(ha,args(arg:end),version);

Answer 1

[the cyclist]

It looks to me that the documentation states the change was in R2018b, not R2018a.

As you can see, that code works fine here (R2021a):

t = 2*pi*(0:0.01:1);
x1 = sin(t);
x2 = cos(t);

figure(1)
plot(t,x1)
hold %on

Current plot held

plot(t,x2)
hold %off

Current plot released

xlim([0 2*pi])
legend('sin(t)','cos(t)','NumColumns',2)

[Phil]

Thanks for your reply! That would certainly explain it. But I'm curious which documentation you're referring to. In the release notes here (click on "Legend Object" under "R2018a" > "Graphics"), it seems to indicate this should work in 2018a.

[Steven Lord]

The following information is in the "Customize Legend Appearance" section on that documentation page:

You can set properties in two ways:

• Use name-value pairs in the legend command. In most cases, when you use name-value pairs, you must specify the labels in a cell array, such as legend({'label1','label2'},'FontSize',14).
• Use the Legend object. You can return the Legend object as an output argument from the legend function, such as lgd = legend. Then, use lgd with dot notation to set properties, such as lgd.FontSize = 14.

You didn't specify your labels as a cell array, so I believe legend interpreted NumColumns as a third label and was confused (and so threw an error) when it saw the 2.

[the cyclist]

I was looking at "Compatibility Considerations" ("legend interprets arguments as property names when property exists") in the documentation for legend.

Frankly, your reference seems to more definitively argue that this functionality should be there in R2018a. ¯\_(ツ)_/¯

(But @Steven Lord's comment is spot-on, I think.)

[Phil]

@Steven Lord Ah, that's it! NumColumns works in R2018a if I use a Legend object as you suggested. Thanks so much!