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,...)
multi.rect(rect.list,...)

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 coordinate of a rectangle or ellipse

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

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

Value

Graphic output

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

# NOT RUN {
#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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