Loren on the Art of MATLAB

Turn ideas into MATLAB

Plotting with Style 65

Posted by Loren Shure,

One of MATLAB's features is being able to customize plots. But some of the customization may not need to be done by hand and can instead be controlled programmatically. Let me show you a set of these having to do with plotting lines.

Contents

Plotting by Adding Lines

If you make a plot by successively adding lines, all the lines, by default, have the same color and linestyle.

m3 = magic(3);
plot(m3(:,1));
hold on
plot(m3(:,2))
plot(m3(:,3))
hold off

As you can see, it's very hard (impossible) to tell which line is which.

Manually Control Color and Style

I can distinguish the lines by using different colors and linestyles. Here's one way to do it.

plot(m3(:,1),'r');
hold on
plot(m3(:,2),':b')
plot(m3(:,3),'g--')
hold off

Vectorizing Line Drawing

I can instead vectorize the line drawing.

plot(m3)

What you see here is the MATLAB cycles through colors to distinguish the plots. How many colors and which ones? Does MATLAB ever cycle through the linestyles? You can find out answers to these questions in the documentation on LineStyle and Color as well as some answers in this article.

Default Line Properties

Let's see what properties lines in MATLAB have. First I'll create a line and then get the properties.

h = plot(m3(:,1));
get(h)
           DisplayName: ''
            Annotation: [1x1 hg.Annotation]
                 Color: [0 0 1]
             EraseMode: 'normal'
             LineStyle: '-'
             LineWidth: 0.5000
                Marker: 'none'
            MarkerSize: 6
       MarkerEdgeColor: 'auto'
       MarkerFaceColor: 'none'
                 XData: [1 2 3]
                 YData: [8 3 4]
                 ZData: [1x0 double]
          BeingDeleted: 'off'
         ButtonDownFcn: []
              Children: [0x1 double]
              Clipping: 'on'
             CreateFcn: []
             DeleteFcn: []
            BusyAction: 'queue'
      HandleVisibility: 'on'
               HitTest: 'on'
         Interruptible: 'on'
              Selected: 'off'
    SelectionHighlight: 'on'
                   Tag: ''
                  Type: 'line'
         UIContextMenu: []
              UserData: []
               Visible: 'on'
                Parent: 161.0015
             XDataMode: 'auto'
           XDataSource: ''
           YDataSource: ''
           ZDataSource: ''

To see what the default properties are, I can use set instead of get.

set(h)
ans = 
           DisplayName: {}
                 Color: {}
             EraseMode: {4x1 cell}
             LineStyle: {5x1 cell}
             LineWidth: {}
                Marker: {14x1 cell}
            MarkerSize: {}
       MarkerEdgeColor: {2x1 cell}
       MarkerFaceColor: {2x1 cell}
                 XData: {}
                 YData: {}
                 ZData: {}
         ButtonDownFcn: {}
              Children: {}
              Clipping: {2x1 cell}
             CreateFcn: {}
             DeleteFcn: {}
            BusyAction: {2x1 cell}
      HandleVisibility: {3x1 cell}
               HitTest: {2x1 cell}
         Interruptible: {2x1 cell}
              Selected: {2x1 cell}
    SelectionHighlight: {2x1 cell}
                   Tag: {}
         UIContextMenu: {}
              UserData: {}
               Visible: {2x1 cell}
                Parent: {}
             XDataMode: {2x1 cell}
           XDataSource: {}
           YDataSource: {}
           ZDataSource: {}

Notice two particular properties, Color and LineStyle. get shows me the current values.

get(h,'Color')
ans =
     0     0     1

set allows me to see the choices for that property.

set(h,'LineStyle')
[ {-} | -- | : | -. | none ]

How Do axes Fit in?

Each line has a color and a linestyle, and they each have defaults, so what determines the behavior when I plotted multiple lines and got different colors? That's related to a property of axes which we can see here.

get(gca)
	ActivePositionProperty = outerposition
	ALim = [0 1]
	ALimMode = auto
	AmbientLightColor = [1 1 1]
	Box = on
	CameraPosition = [2 5.5 17.3205]
	CameraPositionMode = auto
	CameraTarget = [2 5.5 0]
	CameraTargetMode = auto
	CameraUpVector = [0 1 0]
	CameraUpVectorMode = auto
	CameraViewAngle = [6.60861]
	CameraViewAngleMode = auto
	CLim = [0 1]
	CLimMode = auto
	Color = [1 1 1]
	CurrentPoint = [ (2 by 3) double array]
	ColorOrder = [ (7 by 3) double array]
	DataAspectRatio = [1 2.5 1]
	DataAspectRatioMode = auto
	DrawMode = normal
	FontAngle = normal
	FontName = Helvetica
	FontSize = [10]
	FontUnits = points
	FontWeight = normal
	GridLineStyle = :
	Layer = bottom
	LineStyleOrder = -
	LineWidth = [0.5]
	MinorGridLineStyle = :
	NextPlot = replace
	OuterPosition = [0 0 1 1]
	PlotBoxAspectRatio = [1 1 1]
	PlotBoxAspectRatioMode = auto
	Projection = orthographic
	Position = [0.13 0.11 0.775 0.815]
	TickLength = [0.01 0.025]
	TickDir = in
	TickDirMode = auto
	TightInset = [0.0392857 0.0404762 0.00892857 0.0190476]
	Title = [166.002]
	Units = normalized
	View = [0 90]
	XColor = [0 0 0]
	XDir = normal
	XGrid = off
	XLabel = [163.002]
	XAxisLocation = bottom
	XLim = [1 3]
	XLimMode = auto
	XMinorGrid = off
	XMinorTick = off
	XScale = linear
	XTick = [ (1 by 11) double array]
	XTickLabel = [ (11 by 3) char array]
	XTickLabelMode = auto
	XTickMode = auto
	YColor = [0 0 0]
	YDir = normal
	YGrid = off
	YLabel = [164.002]
	YAxisLocation = left
	YLim = [3 8]
	YLimMode = auto
	YMinorGrid = off
	YMinorTick = off
	YScale = linear
	YTick = [ (1 by 11) double array]
	YTickLabel = [ (11 by 3) char array]
	YTickLabelMode = auto
	YTickMode = auto
	ZColor = [0 0 0]
	ZDir = normal
	ZGrid = off
	ZLabel = [165.002]
	ZLim = [-1 1]
	ZLimMode = auto
	ZMinorGrid = off
	ZMinorTick = off
	ZScale = linear
	ZTick = [-1 0 1]
	ZTickLabel = 
	ZTickLabelMode = auto
	ZTickMode = auto

	BeingDeleted = off
	ButtonDownFcn = 
	Children = [162.004]
	Clipping = on
	CreateFcn = 
	DeleteFcn = 
	BusyAction = queue
	HandleVisibility = on
	HitTest = on
	Interruptible = on
	Parent = [1]
	Selected = off
	SelectionHighlight = on
	Tag = 
	Type = axes
	UIContextMenu = []
	UserData = []
	Visible = on

Well, hmmmm -- so many properties. Let me point out the two that are the ones to focus on for now.

get(gca,'ColorOrder')
ans =
         0         0    1.0000
         0    0.5000         0
    1.0000         0         0
         0    0.7500    0.7500
    0.7500         0    0.7500
    0.7500    0.7500         0
    0.2500    0.2500    0.2500
get(gca,'LineStyleOrder')
ans =
-

Note: using gca is really only for debugging or illustration. Normally a handle should be gotten from the chosen axes and that handle specifically should be used.

axes Properties ColorOrder and LineStyleOrder

There are two axes properties that you can set to help you make the lines in your plots follow a pattern of color and linestyle. To see how these work, let's set the defaults for these properties at the root of the handle graphics hierarchy and experiment.

set(0,'DefaultAxesLineStyleOrder',{'--',':'})
set(0,'DefaultAxesColorOrder',[1 0 1; 0 1 1; 0 1 0])
yvals = [1:10;1:10]
plot(yvals)
axis([1 2 0 size(yvals,2)+1 ])
yvals =
     1     2     3     4     5     6     7     8     9    10
     1     2     3     4     5     6     7     8     9    10

Now you see that MATLAB first cycles over the colors using the first linestyle, then again cycles over the colors with the second linestyle, etc., eventually cycling over the linestyles again as well.

Do You Override the Defaults?

Do you override the line plotting defaults? Do you do this manually or by setting the defaults as I have shown here? Let me know here how you avoid hand-updating your plots.


Get the MATLAB code

Published with MATLAB® 7.5

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