newmap

Set up new map

Since R2023a

Syntax

newmap

newmap(proj)

newmap(target,___)

mx = newmap(___)

Description

newmap creates the default map axes in the current figure. By default, the function creates a world map that uses an Equal Earth projection.

In some cases, the newmap function can change the current figure and current axes. For more information, see Algorithms.

newmap(proj) specifies the projected coordinate reference system (CRS) for the map.

newmap(target,___) changes or replaces the axes specified by target instead of the current axes, in addition to any combination of inputs from the previous syntaxes.

mx = newmap(___) returns the MapAxes object. Use mx to query and modify properties of the MapAxes object after creation. For a list of properties, see MapAxes Properties.

Examples

Create Default Map Axes

Create the default map axes. By default, the map axes uses an Equal Earth projection.

newmap

Read a shapefile containing world land areas into the workspace as a geospatial table. Display the land areas on the map axes.

land = readgeotable("landareas.shp");
geoplot(land)

Specify Map Projection of Map Axes

MapAxes objects use projected coordinate reference systems (CRSs) to transform geographic (latitude-longitude) coordinates to projected (xy) coordinates. There are two ways to get a projected CRS:

• Get a projected CRS from a data file.

• Create a projected CRS object by using the projcrs function. You can create a projected CRS object from an authority code or from a well-known text string.

Get Projected CRS from File

Read a shapefile of road data into the workspace as a geospatial table. The table represents the roads using line shapes in projected coordinates.

roads = readgeotable("concord_roads.shp");

Extract the projected CRS from the data file. Then, create a map axes that uses the projected CRS.

proj1 = roads.Shape.ProjectedCRS;
newmap(proj1)

Display the data on the map axes.

geoplot(roads)

Get Projected CRS from Authority Code

Read a shapefile of US states into the workspace as a geospatial table. The table represents the states using polygon shapes in geographic coordinates. Extract the table row representing Alaska.

states = readgeotable("usastatehi.shp");
alaska = states(states.Name == "Alaska",:);

Create a projected CRS object appropriate for Alaska. Use the Alaska Albers Equal Area Conic projected CRS, which has the ESRI code 102006. Then, create a map axes that uses the projected CRS.

proj2 = projcrs(102006,Authority="ESRI");
newmap(proj2)

Display the Alaska polygon on the map axes.

geoplot(alaska)
geolimits([48 72],[-180 -135])

Customize Appearance of Map Axes

Import a shapefile containing road data for Concord, MA into the workspace as a geospatial table. The table represents roads using line shapes in projected coordinates.

roads = readgeotable("concord_roads.shp");

Create a map axes that uses the projected CRS embedded in the data file. Return the MapAxes object as a variable.

proj = roads.Shape.ProjectedCRS;
mx = newmap(proj);

Customize the map by setting properties of the MapAxes object. Set the tick label format to decimal degrees, remove the graticule lines, and change the outline color.

mx.TickLabelFormat = "dd";
mx.GraticuleLineStyle = "none";
mx.OutlineColor = "r";

Display Map Axes in Tiled Layout

Read a shapefile of US states into the workspace as a geospatial table. The table represents the states using polygon shapes in geographic coordinates. Remove the table rows representing Alaska and Hawaii.

states = readgeotable("usastatehi.shp");
idx = states.Name ~= "Alaska" & states.Name ~= "Hawaii";
states = states(idx,:);

Create a 2-by-1 tiled chart layout.

• In the first tile, display the US states over a map axes that uses a North America Albers Equal Area Conic projection.

• In the second tile, display the US states over a geographic axes, which uses a Web Mercator projection.

tiledlayout(2,1)

nexttile
proj = projcrs(102008,Authority="ESRI");
newmap(proj)
geoplot(states)

nexttile
geoplot(states)

Input Arguments

proj — Projected coordinate reference system

projcrs(8857) (default) | projcrs object

Projected coordinate reference system (CRS), specified as a projcrs object. MapAxes objects use the projection method and projection parameters stored in the projected CRS to transform geographic (latitude-longitude) coordinates to projected (xy) coordinates.

By default, map axes objects use the World Geodetic System of 1984 (WGS 84) / Equal Earth Greenwich projected CRS, which has the EPSG code 8857.

The projected CRS must have a forward and inverse projection implementation. Most projected CRSs have a forward and inverse projection implementation.

target — Target to change or replace

Axes object | GeographicAxes object | MapAxes object | Figure object | TiledChartLayout object | ...

Target to change or replace, specified as one of these options:

• An axes object — An Axes, PolarAxes, GeographicAxes, or MapAxes object.

• A parent container — A Figure, Panel, Tab, TiledChartLayout, or GridLayout object.

If you do not specify this argument, then the newmap function uses the current axes.

Algorithms

The behavior of the newmap function depends on the NextPlot properties of the figure and axes.

First, the newmap function queries the NextPlot property of the figure.

• If you specify the target input argument, then the function uses the figure associated with target.

• If you do not specify the target input argument, then the function uses the current figure. If there is no current figure, then the function creates a new figure.

This table shows how the newmap function changes the figure based on the value of NextPlot.

Value of NextPlot	Behavior of newmap
"add" (default)	The newmap function: Uses the current figure or the figure associated with target Does not remove child objects from the figure Does not reset figure properties
"new"	If you do not specify target, then the newmap function creates a new figure and uses it as the current figure. If you specify target, then the function uses the figure associated with target.
"replacechildren"	The newmap function: Uses the current figure or the figure associated with target Removes all child objects, which are not hidden, from the figure Resets the NextPlot property of the figure to "add" This behavior is similar to using the clf function.
"replace"	The newmap function: Uses the current figure or the figure associated with target Removes all child objects from the figure, even if the child objects are hidden Resets all figure properties to their defaults, except Position, Units, PaperPosition, and PaperUnits Resets the NextPlot property of the figure to "add", regardless of user-defined defaults This behavior is similar to using the clf reset syntax of the clf function.

Then, the newmap function queries the NextPlot property of the axes in the figure.

• If you specify the target input argument as an axes, then the function uses target.

• If you do not specify the target input argument, then the function uses the current axes. If there is no current axes, then the function creates a new MapAxes object.

This table shows how the newmap function changes the axes based on the value of NextPlot.

Value of NextPlot	Behavior of newmap
"replace" (default)	When the axes is a MapAxes object, the newmap function: Uses the specified axes Removes all child objects from the axes Resets axes properties, except ProjectedCRS, Position and Units, to their default values When the axes is not a MapAxes object, the newmap function deletes the specified axes and creates a MapAxes object. This behavior is similar to using the cla reset syntax of the cla function.
"add"	When the axes is a MapAxes object, the newmap function: Uses the specified axes Does not remove child objects from the axes Does not reset axes properties When the axes is not a MapAxes object, the newmap function returns an error.
"replacechildren"	When the axes is a MapAxes object, the newmap function: Uses the specified axes Removes all child objects from the axes Resets the ColorOrderIndex and LineStyleOrderIndex properties of the axes to 1, but does not reset other axes properties When the axes is not a MapAxes object, the newmap function deletes the specified axes and creates a MapAxes object. This behavior is similar to using the cla function.
"replaceall"	When the axes is a MapAxes object, the newmap function: Uses the specified axes Removes all child objects from the axes Resets axes properties, except Position and Units, to their default values When the axes is not a MapAxes object, the newmap function deletes the specified axes and creates a MapAxes object. This behavior is similar to using the cla reset syntax of the cla function.

Version History

Introduced in R2023a