diagram: Helper functions for drawing path model diagrams

Description

Path models are used to describe structural equation models or cluster analytic output. These functions provide the primitives for drawing path models. Used as a substitute for some of the functionality of Rgraphviz.

Usage

diagram(fit,...)
dia.rect(x, y = NULL, labels = NULL,  cex = 1,  xlim = c(0, 1), ylim = c(0, 1),
    draw=TRUE, ...)
dia.ellipse(x, y = NULL, labels = NULL, cex=1,e.size=.05, xlim=c(0,1), 
       ylim=c(0,1),draw=TRUE,  ...) 
dia.triangle(x, y = NULL, labels =NULL,  cex = 1, xlim=c(0,1),ylim=c(0,1),...)
dia.ellipse1(x,y,e.size=.05,xlim=c(0,1),ylim=c(0,1),draw=TRUE,...)
dia.shape(x, y = NULL, labels = NULL, cex = 1, 
         e.size=.05, xlim=c(0,1), ylim=c(0,1), shape=1, ...)
dia.arrow(from,to,labels=NULL,scale=1,cex=1,adj=2,both=FALSE,pos=NULL,l.cex,
        gap.size,draw=TRUE,col="black",lty="solid",...)
dia.curve(from,to,labels=NULL,scale=1,...)
dia.curved.arrow(from,to,labels=NULL,scale=1,both=FALSE,dir=NULL,draw=TRUE,...)
dia.self(location,labels=NULL,scale=.8,side=2,draw=TRUE,...)
dia.cone(x=0, y=-2, theta=45, arrow=TRUE,curves=TRUE,add=FALSE,labels=NULL,
      xlim = c(-1, 1), ylim=c(-1,1),... ) 
multi.self(self.list,...)
multi.arrow(arrows.list,...)
multi.curved.arrow(curved.list,l.cex=NULL,...)
multi.rect(rect.list,...)

Value

Graphic output

Arguments

fit: The results from a factor analysis fa, components analysis principal, omega reliability analysis, omega, cluster analysis iclust, topdown (bassAckward) bassAckward or confirmatory factor analysis, cfa, or structural equation model,sem, using the lavaan package.
x: x coordinate of a rectangle or ellipse
y: y coordinate of a rectangle or ellipse
e.size: The size of the ellipse (scaled by the number of variables
labels: Text to insert in rectangle, ellipse, or arrow
cex: adjust the text size
col: line color (normal meaning for plot figures)
lty: line type
l.cex: Adjust the text size in arrows, defaults to cex which in turn defaults to 1
gap.size: Tweak the gap in an arrow to be allow the label to be in a gap
adj: Where to put the label along the arrows (values are then divided by 4)
both: Should the arrows have arrow heads on both ends?
scale: modifies size of rectangle and ellipse as well as the curvature of curves. (For curvature, positive numbers are concave down and to the left
from: arrows and curves go from
to: arrows and curves go to
location: where is the rectangle?
shape: Which shape to draw
xlim: default ranges
ylim: default ranges
draw: Draw the text box
side: Which side of boxes should errors appear
theta: Angle in degrees of vectors
arrow: draw arrows for edges in dia.cone
add: if TRUE, plot on previous plot
curves: if TRUE, draw curves between arrows in dia.cone
pos: The position of the text in . Follows the text positions of 1, 2, 3, 4 or NULL
dir: Should the direction of the curve be calculated dynamically, or set as "up" or "left"
...: Most graphic parameters may be passed here
self.list: list saved from dia.self
arrows.list: lst saved from dia.arrow
curved.list: list saved from dia.curved.arrow
rect.list: list saved from dia.rect

Author

William Revelle

Details

The diagram function calls fa.diagram, omega.diagram, ICLUST.diagram, lavaan.diagram or bassAckward.diagram depending upon the class of the fit input. See those functions for particular parameter values.

The remaining functions are the graphic primitives used by fa.diagram, structure.diagram, omega.diagram, ICLUST.diagram and het.diagram

They create rectangles, ellipses or triangles surrounding text, connect them to straight or curved arrows, and can draw an arrow from and to the same rectangle.

To speed up the plotting, dia.rect and dia.arrow can suppress the actual drawing and return the locations and values to plot. These values can then be directly called by text or rect with matrix input. This leads to an impressive increase in speed when doing many variables.

The functions multi.rect, multi.self, multi.arrow and multi.curved.arrow will take the saved output from the appropriate primitives and then draw them all at once.

Each shape (ellipse, rectangle or triangle) has a left, right, top and bottom and center coordinate that may be used to connect the arrows.

Curves are double-headed arrows. By default they go from one location to another and curve either left or right (if going up or down) or up or down (going left to right). The direction of the curve may be set by dir="up" for left right curvature.

The helper functions were developed to get around the infelicities associated with trying to install Rgraphviz and graphviz.

These functions form the core of fa.diagram,het.diagram.

Better documentation will be added as these functions get improved. Currently the helper functions are just a work around for Rgraphviz.

dia.cone draws a cone with (optionally) arrows as sides and centers to show the problem of factor indeterminacy.

Examples

Run this code

#first, show the primitives
xlim=c(-2,10)
ylim=c(0,10)
plot(NA,xlim=xlim,ylim=ylim,main="Demonstration of diagram functions",axes=FALSE,xlab="",ylab="")
ul <- dia.rect(1,9,labels="upper left",xlim=xlim,ylim=ylim)
ml <- dia.rect(1,6,"middle left",xlim=xlim,ylim=ylim)
ll <- dia.rect(1,3,labels="lower left",xlim=xlim,ylim=ylim)
bl <- dia.rect(1,1,"bottom left",xlim=xlim,ylim=ylim)
lr <- dia.ellipse(7,3,"lower right",xlim=xlim,ylim=ylim,e.size=.07)
ur <- dia.ellipse(7,9,"upper right",xlim=xlim,ylim=ylim,e.size=.07)
mr <- dia.ellipse(7,6,"middle right",xlim=xlim,ylim=ylim,e.size=.07)
lm <- dia.triangle(4,1,"Lower Middle",xlim=xlim,ylim=ylim)
br <- dia.rect(9,1,"bottom right",xlim=xlim,ylim=ylim) 
dia.curve(from=ul$left,to=bl$left,"double headed",scale=-1)

dia.arrow(from=lr,to=ul,labels="right to left")
dia.arrow(from=ul,to=ur,labels="left to right")
dia.curved.arrow(from=lr,to=ll,labels ="right to left")
dia.curved.arrow(to=ur,from=ul,labels ="left to right")
dia.curve(ll$top,ul$bottom,"right")  #for rectangles, specify where to point 

dia.curve(ll$top,ul$bottom,"left",scale=-1)  #for rectangles, specify where to point 
dia.curve(mr,ur,"up")  #but for ellipses, you may just point to it.
dia.curve(mr,lr,"down")
dia.curve(mr,ur,"up")
dia.curved.arrow(mr,ur,"up")  #but for ellipses, you may just point to it.
dia.curved.arrow(mr,lr,"down")  #but for ellipses, you may just point to it.

dia.curved.arrow(ur$right,mr$right,"3")
dia.curve(ml,mr,"across")
dia.curve(ur$right,lr$right,"top down",scale =2)
dia.curved.arrow(br$top,lr$right,"up")
dia.curved.arrow(bl,br,"left to right")
dia.curved.arrow(br,bl,"right to left",scale=-1)
dia.arrow(bl,ll$bottom)
dia.curved.arrow(ml,ll$right)
dia.curved.arrow(mr,lr$top)

#now, put them together in a factor analysis diagram
v9 <- sim.hierarchical()
f3 <- fa(v9,3,rotate="cluster")
fa.diagram(f3,error=TRUE,side=3)

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