xregion

Plot a parabola and create a filled region between x=-5 and x=5.

x = -10:0.25:10;
y = x.^2;
plot(x,y)
xregion(-5,5)

You can modify aspects of a region by setting properties. You can set properties by specifying name-value arguments when you call xregion, or you can set properties later using dot notation.

For example, plot a parabola with a filled region, and customize the fill and boundary line colors by specifying the FaceColor and EdgeColor name-value arguments. Also, specify an output argument to store the ConstantRegion object.

x = -10:0.25:10;
y = x.^2;
plot(x,y)
xr = xregion(-5,5,FaceColor="b",EdgeColor=[0.4 0 0.7]);

Modify the appearance further by setting properties of the ConstantRegion object xr. Change the opacity of the fill color and boundary line color by setting the FaceAlpha and EdgeAlpha properties to numbers from 0 to 1, where 1 is fully opaque. Then, set the boundary line thickness by setting the LineWidth property.

xr.FaceAlpha = 0.1;
xr.EdgeAlpha = 0.5;
xr.LineWidth = 2;

Move the lower and upper boundaries to -3 and 3.

xr.Value = [-3 3];

You can create multiple filled regions by specifying the starting and ending coordinates as vectors of the same size. You can also display entries for these regions in a legend.

For example, create a histogram and two filled regions. Specify an output argument to store both ConstantRegion objects so you can modify them later.

Count = randn(1,1000);
histogram(Count)
xr = xregion([-2 1],[-1 2]);

Specify a color for each region by setting the FaceColor property. Specify a legend entry name for each region by setting the DisplayName property. To access the individual ConstantRegion objects for setting the properties, index into the output argument xr. After setting the properties, display a legend.

xr(1).FaceColor = "r";
xr(1).DisplayName = "Low";
xr(2).FaceColor = "#0073FD";
xr(2).DisplayName = "High";
legend

Create a bar chart with five bars positioned at specific times. Then display a filled region from the second bar to the fourth bar. To contain the three bars within the region, calculate the boundaries by subtracting 30 minutes from the second bar's location and adding 30 minutes to the fourth bar's location.

dt = datetime(2021,1,1,8:12,0,0);
y = [1 5 11 4 3];
bar(dt,y)
xregion(dt(2)-minutes(30), dt(4)+minutes(30))

Create a bar chart of categorical data, and create a filled region that spans the second and third bars. The reordercats function specifies the order of the categories for the bar chart.

cats = categorical(["Pumpkin" "Apple" "Pecan" "Cherry"]);
cats = reordercats(cats,["Pumpkin" "Apple" "Pecan" "Cherry"]);
barlengths = [15 21 33 12];
bar(cats,barlengths)
xregion(cats(2),cats(3))
title("Favorite Pies")

Since R2023b

Create a plot, and add three filled regions. Specify a 2-by-3 matrix with the lower bounds in the first row and the upper bounds in the second row. The first region has a lower bound of -Inf, and the last region has an upper bound of Inf, so the first and last regions are unbounded.

x = 0:0.05:10;
y = sin(x.^2)./(x.^2);
plot(x,y)
X = [-Inf 4 7; 2 5 Inf];
xregion(X)