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Add Labels and Annotations to Geographic Axes

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Geographic axes are a type of axes, similar to Cartesian axes and polar axes. As a result, you can use many MATLAB® graphics functions with geographic axes. This example shows how to convey information about a map by adding a title, a legend, text, and data tips.

By default, most plotting functions reset many of the axes properties. This example retains the plots and customizations in the axes by setting the hold state of the axes to on. Alternatively, you can customize the axes after plotting.

Create Map

Load two files into the workspace:

  • A MAT file containing coordinates that outline the conterminous US states.

  • A table containing county data for New England. 

load("usastates.mat")
statelat = [usastates.Lat];
statelon = [usastates.Lon];

counties = readtable("counties.xlsx");

Plot the data by using the geoplot and geoscatter functions. The functions display the data using geographic axes.

  • Create a line plot from the outlines by using the geoplot function.

  • Create a scatter plot from the county data by using the geoscatter function. Prepare to add data tips by returning the Scatter object in s. 

figure
geoplot(statelat,statelon)
hold on
s = geoscatter(counties,"Latitude","Longitude","filled");

Change the basemap and the geographic limits. 

geobasemap grayland
geolimits([40.85 45.73],[-75.00 -66.50])

Figure contains an axes object with type geoaxes. The geoaxes object contains 2 objects of type line, scatter.

Add Title

Add a title by using the title function. 

title("New England")

Figure contains an axes object with type geoaxes. The geoaxes object contains 2 objects of type line, scatter.

Add Legend

Add a legend with descriptions. Specify the legend labels as inputs to the legend function. For more information about adding legends to axes, see Add Legend to Graph.

legend(["State Outlines","Counties"])

Figure contains an axes object with type geoaxes. The geoaxes object contains 2 objects of type line, scatter. These objects represent State Outlines, Counties.

Change Font Size

Change the font size by using the fontsize function. The fontsize function affects the sizes of fonts used in the title, tick labels, and scale bar, as well as in any legends or color bars associated with the axes. 

fontsize(12,"points")

Figure contains an axes object with type geoaxes. The geoaxes object contains 2 objects of type line, scatter. These objects represent State Outlines, Counties.

To change the font size of only the title, access the title of the current geographic axes object. Then, specify the title as input to the fontsize function.

gx = gca;
t = gx.Title;
fontsize(t,16,"points")

Figure contains an axes object with type geoaxes. The geoaxes object contains 2 objects of type line, scatter. These objects represent State Outlines, Counties.

Add Text

Add text to the map. Specify the location for the text using latitude-longitude coordinates. For more information about adding text to axes, see Add Text to Chart.

text(43,-69,"Atlantic Ocean")

Figure contains an axes object with type geoaxes. The geoaxes object contains 3 objects of type line, scatter, text. These objects represent State Outlines, Counties.

Add Data Tips

Display the coordinates of a county by adding a data tip. Specify the scatter chart and latitude-longitude coordinates as inputs to the datatip function.

dt = datatip(s,42.64,-70.87,Location="southeast");

Display the county name in the data tip by adding a new row to the data tip template. For more information about customizing data tips, see Create Custom Data Tips.

dtRow = dataTipTextRow("County",counties.CountyName);
s.DataTipTemplate.DataTipRows(end+1) = dtRow;

Figure contains an axes object with type geoaxes. The geoaxes object contains 3 objects of type line, scatter, text. These objects represent State Outlines, Counties.

See Also

Functions

Properties

Related Topics