northarrow
Add graphic element pointing to geographic North Pole
Syntax
northarrow
northarrow('property',value,...)
Description
northarrow creates a default
north arrow.
northarrow('property',value,...) creates a north arrow
using the specified property/value pairs. Valid entries for properties are
'latitude', 'longitude',
'facecolor', 'edgecolor',
'linewidth', and 'scaleratio'. The
'latitude' and 'longitude' properties
specify the location of the north arrow. The 'facecolor',
'edgecolor', and 'linewidth' properties
control the appearance of the north arrow. The 'scaleratio' property
represents the size of the north arrow as a fraction of the size of the axes. A
'scaleratio' value of 0.10 creates a north arrow one-tenth (1/10)
the size of the axes. You can change the appearance ('facecolor',
'edgecolor', and 'linewidth') of the north
arrow using the set command.
northarrow creates a north arrow symbol
at the map origin on the displayed map. You can reposition the north
arrow symbol by clicking and dragging its icon. Alternate clicking
the icon creates an input dialog box that you can also use to change
the location of the north arrow.
Modifying some of the properties of the north arrow results
in replacement of the original object. Use HANDLEM('NorthArrow') to
get the handles associated with the north arrow.
Examples
Create a map of the South Pole and then add the north arrow in the upper left of the map.
Antarctica = shaperead('landareas', 'UseGeoCoords', true, ...
'Selector',{@(name) strcmpi(name,{'Antarctica'}), 'Name'});
figure;
worldmap('south pole')
geoshow(Antarctica,'FaceColor',[.9 .9 .9])
northarrow('latitude', -57, 'longitude', 135);
Right-click the north arrow icon to activate the input dialog
box. Increase the size of the north arrow symbol by changing the 'ScaleRatio' property.
Create a map of Texas and add the north arrow in the lower left of the map.
figure; usamap('texas')
states = shaperead('usastatelo.shp','UseGeoCoords',true);
faceColors = makesymbolspec('Polygon',...
{'INDEX', [1 numel(states)], 'FaceColor', ...
polcmap(numel(states))});
geoshow(states, 'DisplayType', 'polygon', ...
'SymbolSpec', faceColors)
northarrow('latitude',25,'longitude',-105,'linewidth',1.5);
Change the 'FaceColor' and 'EdgeColor' properties
of the north arrow.
h = handlem('NorthArrow');
set(h,'FaceColor',[1.000 0.8431 0.0000],...
'EdgeColor',[0.0100 0.0100 0.9000])
Limitations
You can draw multiple north arrows on the map. However, the callbacks will only work with the most recently created north arrow. In addition, since it can be displayed outside the map frame limits, the north arrow is not converted into a “mapped” object. Hence, the location and orientation of the north arrow have to be updated manually if the map origin or projection changes.