rethinking (version 2.13)

drawdag: Plot Directed Acyclic Graphs (dagitty)

Description

A fancier version of dagitty's plot function, as well as a way to show open paths given a conditioning set.

Usage

drawdag( x , col_arrow="black" , col_segment="black" , col_labels="black" , cex=1 , 
  lwd=1.5 , goodarrow=TRUE , xlim , ylim , shapes , col_shapes , radius=3 , 
  add=FALSE , ... )
drawopenpaths( x , Z=list() , col_arrow="red" , ... )

Arguments

x

A dagitty graph

col_arrow

Color or vector of colors for the graph arrows

col_segment

Color or vector of colors for the graph segments

col_labels

Color or vector of colors for the graph text labels

cex

Size of text labels

lwd

Width of arrow lines

goodarrow

Use Arrow from shape package to draw arrows

xlim

Optional plot limits

ylim

Optional plot limits

shapes

A named list of variables with one of "c" for an open circle or "fc" for a filled circle

col_shapes

A named list of colors to correspond to the shapes list

radius

Radius of shapes circles

add

If TRUE, draw over existing DAG in active plot

Z

List of variables to condition on when computing open paths

...

Optional arguments to pass to other functions

Value

Details

drawdag is a modified version of plot.dagitty but with additional stylistic options. By default, it draws arrows in black and with thicker line width. It also uses the nicer arrows drawn by Arrows in the shape package. If the DAG doesn't already have coordinates, then graphLayout is called to provide them.

drawopenpaths uses dagitty::paths to compute and then overdraw open paths, given an exposure and outcome variable. It uses drawdag to perform the drawing. Requires that the DAG already be displayed. Only open paths are drawn in the overlay color.

Examples

# NOT RUN {
ex1 <- dagitty("dag {
    X [exposure]
    Y [outcome]
    U [unobserved]
    Z -> X -> Y
    X <- U -> Y
}")
coordinates(ex1) <- list( x=c(Z=0,X=1,Y=1,U=0) , y=c(Z=0,U=0.5,X=0,Y=1) )
drawdag( ex1 )

# example of drawing open paths
drawdag( ex1 )
drawopenpaths( ex1 ) # open backdoor

drawdag( ex1 , col_arrow="gray" )
drawopenpaths( ex1 , Z=list("U") ) # closed backdoor
# }