Legend Location 'Best', but still in corner if possible - matlab

Question

I want to set the Location of my legend to 'Best' (like legend('y1','y2','Location','Best')) so the legend doesn't collide with my lines, but at the same time, I would prefer to have it in a corner if that's possible with no data collision. Is there a way of implementing this?

Answer 1

In case anyone's interested in this, I wrote a function based on #S.. answer that does, what I wanted to achieve. Here's the code:
function setPositionCornerBest( figureHandle )
%Sets the Location of the legend of the figure that is referenced by figureHandle to one of the Corners if there is no data in the Corners. Otherwise it sets it to 'Best'
h = figureHandle;
figObjects = get(h,'Children');
legHandle = findobj(figObjects,'Tag','legend');
axHandle = findobj(figObjects,'Type','axes','-and','Tag','');
lineHandle = findobj(figObjects,'Type','line','-and','Parent',axHandle);
axPos = get(axHandle,'Position');
LimX = get(axHandle,'XLim');
LimY = get(axHandle,'YLim');
xScaling = (LimX(2)-LimX(1))/axPos(3);
yScaling = (LimY(2)-LimY(1))/axPos(4);
locCell = {'NorthWest','NorthEast','SouthEast','SouthWest'};
ii = 1;
interSecFlag = true;
while (interSecFlag) && (ii<=4)
set(legHandle,'Location',locCell{ii});
legPos = get(legHandle,'Position');
x(1) = LimX(1)+(legPos(1)-axPos(1))*xScaling;
x(2) = x(1);
x(3) = LimX(1)+(legPos(1)+legPos(3)-axPos(1))*xScaling;
x(4) = x(3);
x(5) = x(1);
y(1) = LimY(1)+(legPos(2)-axPos(2))*yScaling;
y(2) = LimY(1)+(legPos(2)+legPos(4)-axPos(2))*yScaling;
y(3) = y(2);
y(4) = y(1);
y(5) = y(1);
for jj = 1:numel(lineHandle)
xline = get(lineHandle(jj),'XData');
yline = get(lineHandle(jj),'YData');
[xInter ~] = intersections(x,y,xline,yline);
if numel(xInter) == 0
xInterFlag(jj) = 0;
else
xInterFlag(jj) = 1;
end
end
if all(xInterFlag==0)
interSecFlag = false;
end
ii = ii + 1;
end
if interSecFlag
set(legHandle,'Location','Best');
end
end

Answer 2

I don't have a complete answer, only a sketch. However, you could try to first set the legend in a corner
a=legend('y1', 'y2', 'Location', 'NorthEast')
and then obtain its position
get(a,'Position')
You can convert this position to coordinates and simply test whether your lines cross any border of the legend using
http://www.mathworks.com/matlabcentral/fileexchange/11837-fast-and-robust-curve-intersections
.If this is the case, try another corner, until there is no corner left. In that case, use 'Best'.