I got a solution from support that works. Here are the details:
Unfortunately, there is not a direct Name-Value pair, property, or function that does this easily, but it is being looked at as a potential future improvement for the "Mapping Toolbox." Instead, we have to implement a bit of a workaround with the labels themselves.
Basically, we will do almost exactly what you had provided, but we will grab all of the labels, modify the degree values, and substitute them back into the map plot. Below is the code that should allow you to do this:
latlim = [47 55]; lonlim = [165 -165];
axesm('mercator','MapLatLimit',latlim,'MapLonLimit',lonlim,...
'Frame','on','Grid','on',...
'ParallelLabel','on',...
'mlabellocation',[165:5:195], ...
'plabellocation',[48:2:56],...
'labelformat','compass',...
'Fontsize',6);
gridm('mlinelocation',5,'plinelocation',2);
h = mlabel('on');
for i=1:length(h) labelString=string(h(i).String{1});
value = str2double(extractBetween(labelString,2,"^"));
value = wrapTo360(value);
if value > 180 value = 360 - value;
labelString = strcat(" ",num2str(value),"^{\circ} W");
h(i).String{1} = labelString;
end
end
They also suggested I include this link as that is almost the reverse of my problem, but might be helpful no matter what your use-case is:
