7.1 Two-Dimensional Graphics
The Axiom two-dimensional graphics package provides the ability
to graphics:two-dimensional display
-
curves defined by functions of a single real variable
- curves defined by parametric equations
- implicit non-singular curves defined by polynomial equations
- planar graphs generated from lists of point components.
These graphs can be modified by specifying various options, such as
calculating points in the polar coordinate system or changing the size
of the graph viewport window.
7.1.1 Plotting Two-Dimensional Functions of One Variable
curve:one variable function The first kind of
two-dimensional graph is that of a curve defined by a function
over a finite interval of the axis.
The general format for drawing a function defined by a formula is:
draw(f(x), x = a..b, options)
where defines the range of , and where options
prescribes zero or more options as described in
ugGraphTwoDOptions . An
example of an option is An alternative
format involving functions and is also available.
A simple way to plot a function is to use a formula. The first
argument is the formula. For the second argument, write the name of
the independent variable (here, ), followed by an ``='', and the
range of values.
Display this formula over the range .
Axiom converts your formula to a compiled function so that the
results can be computed quickly and efficiently.
draw(sin(tan(x)) - tan(sin(x)),x = 0..6)
Once again the formula is converted to a compiled function before any
points were computed. If you want to graph the same function on
several intervals, it is a good idea to define the function first so
that the function has to be compiled only once.
This time we first define the function.
f(x) == (x-1)*(x-2)*(x-3)
Type: Void
To draw the function, the first argument is its name and the second is
just the range with no independent variable.
draw(f, 0..4)
7.1.2 Plotting Two-Dimensional Parametric Plane Curves
The second kind of two-dimensional graph is that of
parametric plane curve curves produced by parametric
equations. curve:parametric plane Let and
be formulas or two functions and as the parameter
ranges over an interval . The function curve takes the
two functions and as its parameters.
The general format for drawing a two-dimensional plane curve defined by
parametric formulas and is:
draw(curve(f(t), g(t)), t = a..b, options)
where defines the range of the independent variable , and
where options prescribes zero or more options as described in
ugGraphThreeDOptions . An
example of an option is
Here's an example:
Define a parametric curve using a range involving , Axiom's way
of saying . For parametric curves, Axiom
compiles two functions, one for each of the functions and .
draw(curve(sin(t)*sin(2*t)*sin(3*t), sin(4*t)*sin(5*t)*sin(6*t)), t = 0..2*%pi)
The title may be an arbitrary string and is an optional argument to
the draw command.
draw(curve(cos(t), sin(t)), t = 0..2*%pi)
If you plan on plotting , as ranges over
several intervals, you may want to define functions and first,
so that they need not be recompiled every time you create a new graph.
Here's an example:
As before, you can first define the functions you wish to draw.
f(t:DFLOAT):DFLOAT == sin(3*t/4)
Function declaration f : DoubleFloat -> DoubleFloat has been
added to workspace.
Type: Void
Axiom compiles them to map DoubleFloat values to DoubleFloat
values.
g(t:DFLOAT):DFLOAT == sin(t)
Function declaration f : DoubleFloat -> DoubleFloat has been added
to workspace.
Type: Void
Give to curve the names of the functions, then write the range
without the name of the independent variable.
draw(curve(f,g),0..%pi)
Here is another look at the same curve but over a different
range. Notice that and are not recompiled. Also note that
Axiom provides a default title based on the first function specified
in curve.
draw(curve(f,g),-4*%pi..4*%pi)
7.1.3 Plotting Plane Algebraic Curves
A third kind of two-dimensional graph is a non-singular
``solution curve'' curve:plane algebraic in a rectangular
region of the plane. A solution curve is a curve defined by a
polynomial equation . plane algebraic curve
Non-singular means that the curve is ``smooth'' in that it does not
cross itself or come to a point (cusp). Algebraically, this means
that for any point on the curve, that is, a point such that
, the partial derivatives
and
are not both zero.
curve:smooth curve:non-singular smooth curve
non-singular curve
The general format for drawing a non-singular solution curve given by
a polynomial of the form is:
draw(p(x,y) = 0, x, y, range == [a..b, c..d], options)
where the second and third arguments name the first and second
independent variables of . A range option is always given to
designate a bounding rectangular region of the plane
.
Zero or more additional options as described in
ugGraphTwoDOptions may be given.
We require that the polynomial has rational or integral coefficients.
Here is an algebraic curve example (``Cartesian ovals''):
Cartesian:ovals
p := ((x**2 + y**2 + 1) - 8*x)**2 - (8*(x**2 + y**2 + 1)-4*x-1)
|
|
Type: Polynomial Integer
The first argument is always expressed as an equation of the form
where is a polynomial.
draw(p = 0, x, y, range == [-1..11, -7..7])
7.1.4 Two-Dimensional Options
The draw commands take an optional list of options, such as title shown above. Each option is given by the syntax:
name == value.
Here is a list of the available options in the
order that they are described below.
| adaptive | clip | unit |
| clip | curveColor | range |
| toScale | pointColor | coordinates |
The option turns adaptive plotting on or off.
adaptive plotting Adaptive plotting uses an algorithm that
traverses a graph and computes more points for those parts of the
graph with high curvature. The higher the curvature of a region is,
the more points the algorithm computes.
graphics:2D options:adaptive
The adaptive option is normally on. Here we turn it off.
draw(sin(1/x),x=-2*%pi..2*%pi, adaptive == false)
The clip option turns clipping on or off.
graphics:2D options:clipping
If on, large values are cut off according to
clipPointsDefaultclipPointsDefaultGraphicsDefaults.
draw(tan(x),x=-2*%pi..2*%pi, clip == true)
Option toScale does plotting to scale if true or uses the
entire viewport if false. The default can be determined using
drawToScaledrawToScaleGraphicsDefaults.
graphics:2D options:to scale
draw(sin(x),x=-%pi..%pi, toScale == true, unit == [1.0,1.0])
Option clip with a range sets point clipping of a graph within
the graphics:2D options:clip in a range ranges specified in
the list . clipping If only one range is
specified, clipping applies to the y-axis.
draw(sec(x),x=-2*%pi..2*%pi, clip == [-2*%pi..2*%pi,-%pi..%pi], unit == [1.0,1.0])
Option curveColor sets the color of the graph curves or lines to
be the graphics:2D options:curve color indicated palette color
curve:color (see ugGraphColor and
ugGraphColorPalette ).
color:curve
draw(sin(x),x=-%pi..%pi, curveColor == bright red())
Option pointColor sets the color of the graph points to the
indicated graphics:2D options:point color palette color (see
ugGraphColor and
ugGraphColorPalette ).
color:point
draw(sin(x),x=-%pi..%pi, pointColor == pastel yellow())
Option unit sets the intervals at which the axis units are
plotted graphics:2D options:set units according to the
indicated steps [ interval, interval].
draw(curve(9*sin(3*t/4),8*sin(t)), t = -4*%pi..4*%pi, unit == [2.0,1.0])
Option range sets the range of variables in a graph to be within
the ranges graphics:2D options:range for solving plane
algebraic curve plots.
draw(y**2 + y - (x**3 - x) = 0, x, y, range == [-2..2,-2..1], unit==[1.0,1.0])
A second example of a solution plot.
draw(x**2 + y**2 = 1, x, y, range == [-3/2..3/2,-3/2..3/2], unit==[0.5,0.5])
Option indicates the coordinate system in which the
graph graphics:2D options:coordinates is plotted. The default
is to use the Cartesian coordinate system.
Cartesian:coordinate system For more details, see
ugGraphCoord
or CoordinateSystems.
coordinate system:Cartesian
draw(curve(sin(5*t),t),t=0..2*%pi, coordinates == polar)
7.1.5 Color
The domain Color Color provides operations for
manipulating graphics:color colors in two-dimensional
graphs. color Colors are objects of Color. Each color
has a hue and a weight. hue Hues are represented
by integers that range from to the
numberOfHues()numberOfHues()Color, normally
graphics:color:number of hues . weight Weights
are floats and have the value by default.
- color (integer)
-
creates a color of hue integer and weight .
- hue (color)
-
returns the hue of color as an integer.
graphics:color:hue function
- red ()
-
blue(),
green(), and yellow()
graphics:color:primary color functions
create colors of that hue with weight .
- +
- returns the
color that results from additively combining the indicated
and .
Color addition is not commutative: changing the order of the arguments
produces different results.
- integer * color
-
changes the weight of color by integer
without affecting its hue.
graphics:color:multiply function
For example,
produces a color closer to yellow than to red.
Color multiplication is not associative: changing the order of grouping
color:multiplication
produces different results.
These functions can be used to change the point and curve colors
for two- and three-dimensional graphs.
Use the pointColor option for points.
draw(x**2,x=-1..1,pointColor == green())
Use the curveColor option for curves.
draw(x**2,x=-1..1,curveColor == color(13) + 2*blue())
7.1.6 Palette
graphics:palette
Domain Palette is the domain of shades of colors:
dark, dim, bright, pastel, and light,
designated by the integers through , respectively.
Palette
Colors are normally ``bright.''
Type: PositiveInteger
To change the shade of a color, apply the name of a shade to it.
color:shade
shade
myFavoriteColor := dark blue()
|
|
Type: Palette
The expression
returns the value of a shade of .
Type: PositiveInteger
The expression returns its hue.
Type: Color
Palettes can be used in specifying colors in two-dimensional graphs.
draw(x**2,x=-1..1,curveColor == dark blue())
7.1.7 Two-Dimensional Control-Panel
graphics:2D control-panel
Once you have created a viewport, move your mouse to the viewport and click
with your left mouse button to display a control-panel.
The panel is displayed on the side of the viewport closest to
where you clicked. Each of the buttons which toggle on and off show the
current state of the graph.
7.1.7.1 Transformations
graphics:2D control-panel:transformations
Object transformations are executed from the control-panel by mouse-activated
potentiometer windows.
- Scale:
- To scale a graph, click on a mouse button
graphics:2D control-panel:scale
within the Scale window in the upper left corner of the control-panel.
The axes along which the scaling is to occur are indicated by setting the
toggles above the arrow.
With X On and Y On appearing, both axes are selected and scaling
is uniform.
If either is not selected, for example, if X Off appears, scaling is
non-uniform.
- Translate:
- To translate a graph, click the mouse in the
graphics:2D control-panel:translate
Translate window in the direction you wish the graph to move.
This window is located in the upper right corner of the control-panel.
Along the top of the Translate window are two buttons for selecting
the direction of translation.
Translation along both coordinate axes results when X On and Y
On appear or along one axis when one is on, for example, X On and
Y Off appear.
7.1.7.2 Messages
graphics:2D control-panel:messages
The window directly below the transformation potentiometer windows is
used to display system messages relating to the viewport and the control-panel.
The following format is displayed:
[scaleX, scaleY] graph [translateX, translateY]
The two values to the left show the scale factor along the X and
Y coordinate axes. The two values to the right show the distance of
translation from the center in the X and Y directions. The number
in the center shows which graph in the viewport this data pertains to.
When multiple graphs exist in the same viewport,
the graph must be selected (see ``Multiple Graphs,'' below) in
order for its transformation data to be shown, otherwise the number
is 1.
7.1.7.3 Multiple Graphs
graphics:2D control-panel:multiple graphs
The Graphs window contains buttons that allow the placement
of two-dimensional graphs into one of nine available slots in any other
two-dimensional viewport.
In the center of the window are numeral buttons from one to nine
that show whether a graph is displayed in the viewport.
Below each number button is a button showing whether a graph
that is present is selected for application of some
transformation.
When the caret symbol is displayed, then the graph in that slot
will be manipulated.
Initially, the graph for which the viewport is created occupies
the first slot, is displayed, and is selected.
- Clear:
- The Clear button deselects every viewport graph slot.
graphics:2D control-panel:clear
A graph slot is reselected by selecting the button below its number.
- Query:
- The Query button is used to display the scale and
graphics:2D control-panel:query
translate data for the indicated graph. When this button is selected the
message ``Click on the graph to query'' appears. Select a slot
number button from the Graphs window. The scaling factor and translation
offset of the graph are then displayed in the message window.
- Pick:
- The Pick button is used to select a graph
graphics:2D control-panel:pick
to be placed or dropped into the indicated viewport. When this button is
selected, the message ``Click on the graph to pick'' appears.
Click on the slot with the graph number of the desired
graph. The graph information is held waiting for
you to execute a Drop in some other graph.
- Drop:
- Once a graph has been picked up using the Pick button,
graphics:2D control-panel:drop
the Drop button places it into a new viewport slot.
The message ``Click on the graph to drop'' appears in the message
window when the Drop button is selected.
By selecting one of the slot number buttons in the Graphs
window, the graph currently being held is dropped into this slot
and displayed.
7.1.7.4 Buttons
graphics:2D control-panel:buttons
- Axes
- turns the coordinate axes on or off.
graphics:2D control-panel:axes
- Units
- turns the units along the x
and y axis on or off.
graphics:2D control-panel:units
- Box
- encloses the area of the viewport graph
in a bounding box, or removes the box if already enclosed.
graphics:2D control-panel:box
- Pts
- turns on or off the display of points.
graphics:2D control-panel:points
- Lines
- turns on or off the display
of lines connecting points.
graphics:2D control-panel:lines
- PS
- writes the current viewport contents to
graphics:2D control-panel:ps
a file axiom2D.ps or to a name specified in the user's
graphics:.Xdefaults:PostScript file name
.Xdefaults file.
file:.Xdefaults @ .Xdefaults
The file is placed in the directory from which Axiom or the
viewAlone program was invoked.
PostScript
- Reset
- resets the object transformation
characteristics and attributes back to their initial states.
graphics:2D control-panel:reset
- Hide
- makes the control-panel disappear.
graphics:2D control-panel:hide
- Quit
- queries whether the current viewport
graphics:2D control-panel:quit
session should be terminated.
7.1.8 Operations for Two-Dimensional Graphics
Here is a summary of useful Axiom operations for two-dimensional
graphics.
Each operation name is followed by a list of arguments.
Each argument is written as a variable informally named according
to the type of the argument (for example, integer).
If appropriate, a default value for an argument is given in
parentheses immediately following the name.
- adaptive ([boolean(true)])
-
adaptive plotting
sets or indicates whether graphs are plotted
graphics:set 2D defaults:adaptive
according to the adaptive refinement algorithm.
- axesColorDefault ([color(dark blue())])
-
sets or indicates the default color of the
graphics:set 2D defaults:axes color
axes in a two-dimensional graph viewport.
- clipPointsDefault ([boolean(false)])
-
sets or
indicates whether point clipping is
graphics:set 2D defaults:clip points
to be applied as the default for graph plots.
- drawToScale ([boolean(false)])
-
sets or
indicates whether the plot of a graph
graphics:set 2D defaults:to scale
is ``to scale'' or uses the entire viewport space as the default.
- lineColorDefault ([color(pastel yellow())])
-
sets or indicates the default color of the
graphics:set 2D defaults:line color
lines or curves in a two-dimensional graph viewport.
- maxPoints ([integer(500)])
-
sets or indicates
the default maximum number of
graphics:set 2D defaults:max points
possible points to be used when constructing a two-dimensional graph.
- minPoints ([integer(21)])
-
sets or indicates the default minimum number of
graphics:set 2D defaults:min points
possible points to be used when constructing a two-dimensional graph.
- pointColorDefault ([color(bright red())])
-
sets or indicates the default color of the
graphics:set 2D defaults:point color
points in a two-dimensional graph viewport.
- pointSizeDefault ([integer(5)])
-
sets or indicates the default size of the
graphics:set 2D defaults:point size
dot used to plot points in a two-dimensional graph.
- screenResolution ([integer(600)])
-
sets or indicates the default screen
graphics:set 2D defaults:screen resolution
resolution constant used in setting the computation limit of adaptively
adaptive plotting
generated curve plots.
- unitsColorDefault ([color(dim green())])
-
sets or indicates the default color of the
graphics:set 2D defaults:units color
unit labels in a two-dimensional graph viewport.
- viewDefaults ()
-
resets the default settings for the following
graphics:set 2D defaults:reset viewport
attributes: point color, line color, axes color, units color, point size,
viewport upper left-hand corner position, and the viewport size.
- viewPosDefault ([list([100,100])])
-
sets or indicates the default position of the
graphics:set 2D defaults:viewport position
upper left-hand corner of a two-dimensional viewport, relative to the
display root window.
The upper left-hand corner of the display is considered to be at the
(0, 0) position.
- viewSizeDefault ([list([200,200])])
-
sets or
indicates the default size in which two
graphics:set 2D defaults:viewport size
dimensional viewport windows are shown.
It is defined by a width and then a height.
- viewWriteAvailable ([list(["pixmap","bitmap", "postscript", "image"])])
-
indicates the possible file types
graphics:2D defaults:available viewport writes
that can be created with the writewriteTwoDimensionalViewport function.
- viewWriteDefault ([list([])])
-
sets or indicates the default types of files, in
graphics:set 2D defaults:write viewport
addition to the data file, that are created when a
write function is executed on a viewport.
- units (viewport, integer(1), string("off"))
-
turns the units on or off for the graph with index integer.
- axes (viewport, integer(1), string("on"))
-
turns the axes on
graphics:2D commands:axes
or off for the graph with index integer.
- close (viewport)
-
closes viewport.
graphics:2D commands:close
- connect (viewport, integer(1), string("on"))
-
declares whether lines
graphics:2D commands:connect
connecting the points are displayed or not.
- controlPanel (viewport, string("off"))
-
declares
whether the two-dimensional control-panel is automatically displayed
or not.
- graphs (viewport)
-
returns a list
graphics:2D commands:graphs
describing the state of each graph.
If the graph state is not being used this is shown by "undefined",
otherwise a description of the graph's contents is shown.
- graphStates (viewport)
-
displays
graphics:2D commands:state of graphs
a list of all the graph states available for viewport, giving the
values for every property.
- key (viewport)
-
returns the process
graphics:2D commands:key
ID number for viewport.
- move (viewport,
(viewPosDefault),
(viewPosDefault))
-
moves viewport on the screen so that the
graphics:2D commands:move
upper left-hand corner of viewport is at the position (x,y).
- options (viewport)
-
returns a list
graphics:2D commands:options
of all the DrawOptions used by viewport.
- points (viewport, integer(1), string("on"))
-
specifies whether the graph points for graph integer are
graphics:2D commands:points
to be displayed or not.
- region (viewport, integer(1), string("off"))
-
declares whether graph integer is or is not to be displayed
with a bounding rectangle.
- reset (viewport)
-
resets all the properties of viewport.
- resize (viewport,
, )
-
graphics:2D commands:resize
resizes viewport with a new width and height.
- scale (viewport, (1),
(0.9), (0.9))
-
scales values for the
graphics:2D commands:scale
x and y coordinates of graph n.
- show (viewport, (1),
string("on"))
-
indicates if graph n is shown or not.
- title (viewport, string("Axiom 2D"))
-
designates the title for viewport.
- translate (viewport,
(1),
(0.0), (0.0))
-
graphics:2D commands:translate
causes graph n to be moved x and y units in the respective directions.
- write (viewport, ,
[strings])
-
if no third argument is given, writes the data file onto the directory
with extension data.
The third argument can be a single string or a list of strings with some or
all the entries "pixmap", "bitmap", "postscript", and
"image".
7.1.9 Addendum: Building Two-Dimensional Graphs
In this section we demonstrate how to create two-dimensional graphs from
lists of points and give an example showing how to read the lists
of points from a file.
7.1.9.1 Creating a Two-Dimensional Viewport from a List of Points
Axiom creates lists of points in a two-dimensional viewport by utilizing
the GraphImage and TwoDimensionalViewport domains.
In this example, the makeGraphImagemakeGraphImageGraphImage
function takes a list of lists of points parameter, a list of colors for
each point in the graph, a list of colors for each line in the graph, and
a list of sizes for each point in the graph.
The following expressions create a list of lists of points which will be read
by Axiom and made into a two-dimensional viewport.
p1 := point [1,1]$(Point DFLOAT)
Type: Point DoubleFloat
p2 := point [0,1]$(Point DFLOAT)
Type: Point DoubleFloat
p3 := point [0,0]$(Point DFLOAT)
Type: Point DoubleFloat
p4 := point [1,0]$(Point DFLOAT)
Type: Point DoubleFloat
p5 := point [1,.5]$(Point DFLOAT)
Type: Point DoubleFloat
p6 := point [.5,0]$(Point DFLOAT)
Type: Point DoubleFloat
p7 := point [0,0.5]$(Point DFLOAT)
Type: Point DoubleFloat
p8 := point [.5,1]$(Point DFLOAT)
Type: Point DoubleFloat
p9 := point [.25,.25]$(Point DFLOAT)
Type: Point DoubleFloat
p10 := point [.25,.75]$(Point DFLOAT)
Type: Point DoubleFloat
p11 := point [.75,.75]$(Point DFLOAT)
Type: Point DoubleFloat
p12 := point [.75,.25]$(Point DFLOAT)
Type: Point DoubleFloat
Finally, here is the list.
llp := [ [p1,p2], [p2,p3], [p3,p4], [p4,p1], [p5,p6], [p6,p7], [p7,p8], [p8,p5], [p9,p10], [p10,p11], [p11,p12], [p12,p9] ]
|
|
Type: List List Point DoubleFloat
Now we set the point sizes for all components of the graph.
size1 := 6::PositiveInteger
Type: PositiveInteger
size2 := 8::PositiveInteger
Type: PositiveInteger
size3 := 10::PositiveInteger
lsize := [size1, size1, size1, size1, size2, size2, size2, size2, size3, size3, size3, size3]
|
|
Type: List Polynomial Integer
Here are the colors for the points.
|
|
Type: Palette
|
|
Type: Palette
|
|
Type: Palette
lpc := [pc1, pc1, pc1, pc1, pc2, pc2, pc2, pc2, pc3, pc3, pc3, pc3]
|
|
Type: List Palette
Here are the colors for the lines.
lc := [pastel blue(), light yellow(), dim green(), bright red(), light green(), dim yellow(), bright blue(), dark red(), pastel red(), light blue(), dim green(), light yellow()]
|
|
Type: List Palette
Now the GraphImage is created according to the component
specifications indicated above.
g := makeGraphImage(llp,lpc,lc,lsize)$GRIMAGE
The makeViewport2DmakeViewport2DTwoDimensionalViewport function now
creates a TwoDimensionalViewport for this graph according to the
list of options specified within the brackets.
makeViewport2D(g,[title("Lines")])$VIEW2D
This example demonstrates the use of the GraphImage functions
componentcomponentGraphImage and appendPointappendPointGraphImage
in adding points to an empty GraphImage.
g := graphImage()$GRIMAGE
Type: GraphImage
p1 := point [0,0]$(Point DFLOAT)
Type: Point DoubleFloat
p2 := point [.25,.25]$(Point DFLOAT)
Type: Point DoubleFloat
p3 := point [.5,.5]$(Point DFLOAT)
Type: Point DoubleFloat
p4 := point [.75,.75]$(Point DFLOAT)
Type: Point DoubleFloat
p5 := point [1,1]$(Point DFLOAT)
Type: Point DoubleFloat
Type: Void
Type: Void
appendPoint(g,p3)$GRIMAGE
Type: Void
appendPoint(g,p4)$GRIMAGE
Type: Void
appendPoint(g,p5)$GRIMAGE
Type: Void
g1 := makeGraphImage(g)$GRIMAGE
Here is the graph.
makeViewport2D(g1,[title("Graph Points")])$VIEW2D
A list of points can also be made into a GraphImage by using
the operation coercecoerceGraphImage. It is equivalent to adding
each point to using componentcomponentGraphImage.
g2 := coerce([ [p1],[p2],[p3],[p4],[p5] ])$GRIMAGE
Now, create an empty TwoDimensionalViewport.
options(v,[title("Just Points")])$VIEW2D
Place the graph into the viewport.
Take a look.
makeViewport2D(v)$VIEW2D
7.1.9.2 Creating a Two-Dimensional Viewport of a List of Points from a File
The following three functions read a list of points from a
file and then draw the points and the connecting lines. The
points are stored in the file in readable form as floating point numbers
(specifically, DoubleFloat values) as an alternating
stream of - and -values. For example,
0.0 0.0 1.0 1.0 2.0 4.0
3.0 9.0 4.0 16.0 5.0 25.0
drawPoints(lp:List Point DoubleFloat):VIEW2D ==
g := graphImage()$GRIMAGE
for p in lp repeat
component(g,p,pointColorDefault(),lineColorDefault(),
pointSizeDefault())
gi := makeGraphImage(g)$GRIMAGE
makeViewport2D(gi,[title("Points")])$VIEW2D
drawLines(lp:List Point DoubleFloat):VIEW2D ==
g := graphImage()$GRIMAGE
component(g, lp, pointColorDefault(), lineColorDefault(),
pointSizeDefault())$GRIMAGE
gi := makeGraphImage(g)$GRIMAGE
makeViewport2D(gi,[title("Points")])$VIEW2D
plotData2D(name, title) ==
f:File(DFLOAT) := open(name,"input")
lp:LIST(Point DFLOAT) := empty()
while ((x := readIfCan!(f)) case DFLOAT) repeat
y : DFLOAT := read!(f)
lp := cons(point [x,y]$(Point DFLOAT), lp)
lp
close!(f)
drawPoints(lp)
drawLines(lp)
This command will actually create the viewport and the graph if
the point data is in the file .
plotData2D("file.data", "2D Data Plot")
7.1.10 Addendum: Appending a Graph to a Viewport Window Containing a Graph
This section demonstrates how to append a two-dimensional graph to a viewport
already containing other graphs.
The default draw command places a graph into the first
GraphImage slot position of the TwoDimensionalViewport.
This graph is in the first slot in its viewport.
v1 := draw(sin(x),x=0..2*%pi)
So is this graph.
v2 := draw(cos(x),x=0..2*%pi, curveColor==light red())
The operation getGraphgetGraphTwoDimensionalViewport
retrieves the GraphImage from the first slot position
in the viewport .
Now putGraphputGraphTwoDimensionalViewport
places into the the second slot position of .
Display the new TwoDimensionalViewport containing both graphs.
makeViewport2D(v2)