about moving datacursor in color plot

Question

Ki 2013-10-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/89615-about-moving-datacursor-in-color-plot

评论： Ki 2013-10-9

I am using matlab to plot a false color map and trigger the data cursor, I found that if the map is n-by-n (square), I can use the up/down/left/right arrow to move the data cursor to the next point and show the tip, but if the map is not square (n-by-m), then using up/down still can move it up or down but pressing left or right will cause the data cursor jumping, why's that?

function MyMain
  M=rand(400, 600); 
  pcolor(M); 
  shading flat;
    cursorMode = datacursormode(gcf);
    datacursormode on;
    set(cursorMode, 'UpdateFcn', {@myupdate, M});  
  end
function output_txt = myupdate(obj, event_obj, M)
  pos = get(event_obj,'Position');
  idx = get(event_obj, 'DataIndex');
  val = M(idx);
  output_txt = {['X: ',num2str(pos(1),10)], ['Y: ',num2str(pos(2),10)]};
    if length(pos) > 2
      val = M(idx);
      output_txt{end+1} = ['VAL: ',num2str(val, 10)];
    end
  end

By the way, in above code, I pass the map to the callback function so to show the value at current position, but it is so slow if the data is big. Any way to the data cursor tip refer to the value without passing the whole matrix? Thanks.