Data cursor does not show lat and long values in a contourm plot (worldmap function)

I want to overlay a data set into North America. I used MATLAB's worldmap() function to get just North America and used plotm() to plot the coastline of North America from coast.mat(this file also comes with MATLAB). I then used contourm() to plot my data over the coast lines. The code below shows what I did.

 hold on
 h= worldmap('na');
 c = load('coast.mat');
 plotm(c.lat,c.long);
 contourm(lat,long,value);

"lat" and "long" contain latitude and longitude and are of sizes,lets say 'm' and 'n'. "value" has the data to be plotted which is a matrix of size m x n. The data plots fine but the only problem is that when I use the data cursor, instead of seeing values used in plotting: latitude for "y", longitude for "x" and "value" for z I see really large numbers for x and y and always a 0 for z.

The return from

 h=worldmap('na')

shows similar large values for XLimit and YLimit. I tried to change this to the coordinate limits but the graph basically disappeared with out any error.I also tried creating a custom data cursor but I could not get to accurately change the values to geo coordinates.

Any help would be appreciated!

Answer 1

[Chad Greene]

Try using inputm instead of the data cursor.

[Bipush Osti]

I tried to use it but was not successful in it. Could not find any examples either.What I tried to do was: [lat,long]=inputm; and use that lat and long to show in the custom datatip function that I have. This does not work.

[Chad Greene]

In what way does it not work?

[Bipush Osti]

This is what my data cursor function looks like. I am using data cursor because I want the user to be able to see where they clicked on the map.

 %Function for data cursor
function output_txt = new_datacursor(obj,event_obj)
 pos = get(event_obj,'Position');
 [lat_loc,lon_loc] = inputm;
 output_txt = {['lon: ',lon_loc],...
    ['lat: ',lat_loc]};
  disp(pos);
  % If there is a Z-coordinate in the position, display it as well
  if length(pos) > 2
    output_txt{end+1} = ['value: ',num2str(pos(3),4)];
end

And the error/warning I get (in orange than in red colour) is:

 Warning: Error occurred while executing callback:
Error using matlab.graphics.shape.internal.AxesLayoutManager/MarkDirty
Attempt to modify the tree during an update traversal

 Error in matlab.graphics.shape.internal.AxesLayoutManager>@(obj,evd)(hObj.MarkDirty('all')) (line 351)

 Error in matlab.graphics.shape.internal.AxesLayoutManager/addAxesListeners/localReparentCB (line 333)

[Chad Greene]

Strange! I'm afraid I don't understand that warning at all. Does this work for you?

hold on
h= worldmap('na');
c = load('coast.mat');
plotm(c.lat,c.long);

z = peaks(180); 
[long,lat] = meshgrid(-179:0,89.5:-.5:0);
contourm(lat,long,z);

[lat_loc,lon_loc] = inputm(1);

t = textm(lat_loc,lon_loc,...
    ['(',num2str(lat_loc),'\circ N, ',num2str(lat_loc),'\circ S)'],...
    'vert','middle','horiz','center');

Similarly, you may be able to use ginput with minvtran.