Legend showing same symbol for loop plot

My legend is showing the same symbol for different data. My code is as follows

for i=1:size(obs,1)
    x = V(:,1)'*obs(i,:)';
    y = V(:,2)'*obs(i,:)';
    z = V(:,3)'*obs(i,:)';
    if(grp{i}=='Cancer')
        plot3(x,y,z,'r+','LineWidth',2);
    else
        plot3(x,y,z,'ko','LineWidth',2);
    end
end

Unrecognized function or variable 'obs'.

xlabel ('V1 modes')
ylabel ('V2 modes')
zlabel ('V3 modes')
legend('Cancer Patients', 'Normal Patients')

In the output, the legend is showins the 'r+' for both cancer patients and normal patients

Answer 1

[Adam Danz]

Try this

for i=1:size(obs,1)
    x = V(:,1)'*obs(i,:)';
    y = V(:,2)'*obs(i,:)';
    z = V(:,3)'*obs(i,:)';
    if(grp{i}=='Cancer')
        hc = plot3(x,y,z,'r+','LineWidth',2,'DisplayName','Cancer');
    else
        hn = plot3(x,y,z,'ko','LineWidth',2,'DisplayName', 'Normal');
    end
end
legend([hc,hn])

If you still only see the Cancer group in the legend, check that grp contains character vectors that aren't 'Cancer'.

[Cutie]

I works, thanks.