pathDiagram: Draw Path Diagram

Description

pathDiagram creates a description of the path diagram for a structural-equation-model object to be processed by the graph-drawing program dot, which can be called automatically; see Koutsofios and North (2002) and http://www.graphviz.org/. To obtain graphics output directly, the dot program must be on the system search path.

Usage

## S3 method for class 'sem':
pathDiagram(model, file, min.rank=NULL, max.rank=NULL,
	same.rank=NULL, variables=model$var.names, parameters=rownames(model$ram),
	ignore.double=TRUE, edge.labels=c("names", "values", "both"), 
	size=c(8, 8), node.font=c("Helvetica", 14),
	edge.font=c("Helvetica", 10), rank.direction=c("LR", "TB"), 
	digits=2, standardize=FALSE, output.type=c("graphics", "dot"),
	graphics.fmt="pdf", dot.options=NULL, ...)

Arguments

model

a structural-equation-model object produced by sem.

...

ignored.

file

a file name, given without an extension, to which to write the dot description of the path diagram and, by default, to use that to draw a graph of the model; if not specified, the dot description is written to standar

min.rank

a character string listing names of variables to be assigned minimum rank (order) in the graph; the names should be separated by commas.

max.rank

a character string listing names of variables to be assigned maximum rank in the graph; the names should be separated by commas.

same.rank

a character string or vector of character strings of variables to be assigned equivalent rank in the graph; names in each string should be separated by commas.

variables

variable names; defaults to the variable names in model. If specified, the variable names should be in the same order as in model.

parameters

parameter names; defaults to the parameter names in model. If specified, the parameter names should be in the same order as in model.

ignore.double

if TRUE, the default, double-headed arrows, representing variances and covariances, are not graphed.

edge.labels

"names" to label arrows with parameter names; "values" to label arrows with parameter estimates, or "both".

size

the size of the graph, in inches.

node.font

font name and point-size for printing variable names.

edge.font

font name and point-size for printing arrow names or values.

rank.direction

draw graph left-to-right, "LR", the default, or top-to-bottom, "TB".

digits

number of digits after the decimal point (default, 2) to which to round parameter estimates.

standardize

if TRUE, display standardized coefficients; default is FALSE.

output.type

if "graphics", the default, both a ".dot" file and a graphics file will be created.

graphics.fmt

a graphics format recognized by the dot program; the default is "pdf"; graphics.fmt is also used for the extension of the graphics file that is created.

dot.options

options to be passed to the dot program, given as a character string.

Value

NULL: pathDiagram is used for its side-effect, producing a graph description of the model.

References

Koutsofios, E., and North, S. C. (2002) Drawing graphs with dot. http://www.graphviz.org/Documentation/dotguide.pdf.

Examples

Run this code

# The Duncan, Haller, and Portes Peer-Influences Model

R.DHP <- readMoments(diag=FALSE, names=c('ROccAsp', 'REdAsp', 'FOccAsp', 
                'FEdAsp', 'RParAsp', 'RIQ', 'RSES', 'FSES', 'FIQ', 'FParAsp'))
    .6247                                                              
    .3269  .3669                                                        
    .4216  .3275  .6404                                      
    .2137  .2742  .1124  .0839                                
    .4105  .4043  .2903  .2598  .1839                          
    .3240  .4047  .3054  .2786  .0489  .2220                    
    .2930  .2407  .4105  .3607  .0186  .1861  .2707              
    .2995  .2863  .5191  .5007  .0782  .3355  .2302  .2950        
    .0760  .0702  .2784  .1988  .1147  .1021  .0931 -.0438  .2087  

model.dhp <- specifyModel()
    RParAsp  -> RGenAsp, gam11,  NA
    RIQ      -> RGenAsp, gam12,  NA
    RSES     -> RGenAsp, gam13,  NA
    FSES     -> RGenAsp, gam14,  NA
    RSES     -> FGenAsp, gam23,  NA
    FSES     -> FGenAsp, gam24,  NA
    FIQ      -> FGenAsp, gam25,  NA
    FParAsp  -> FGenAsp, gam26,  NA
    FGenAsp  -> RGenAsp, beta12, NA
    RGenAsp  -> FGenAsp, beta21, NA
    RGenAsp  -> ROccAsp,  NA,       1
    RGenAsp  -> REdAsp,  lam21,  NA
    FGenAsp  -> FOccAsp,  NA,       1
    FGenAsp  -> FEdAsp,  lam42,  NA
    RGenAsp <-> RGenAsp, ps11,   NA
    FGenAsp <-> FGenAsp, ps22,   NA
    RGenAsp <-> FGenAsp, ps12,   NA
    ROccAsp <-> ROccAsp, theta1, NA
    REdAsp  <-> REdAsp,  theta2, NA
    FOccAsp <-> FOccAsp, theta3, NA
    FEdAsp  <-> FEdAsp,  theta4, NA

sem.dhp <- sem(model.dhp, R.DHP, 329,
    fixed.x=c('RParAsp', 'RIQ', 'RSES', 'FSES', 'FIQ', 'FParAsp'))
    
pathDiagram(sem.dhp, min.rank='RIQ, RSES, RParAsp, FParAsp, FSES, FIQ', 
    max.rank='ROccAsp, REdAsp, FEdAsp, FOccAsp')