display nonsignificant coefficients with ggplot2 and legend display

Question

I am trying to show different colors for coefficients that are not significant (p>0.05) and the ones that are. Plus, if someone has a way to show the legend or signify the colors that would also be nice..

Any ideas?

Sample code:

library(nycflights13)
library(dplyr)
library(dotwhisker)
library(MASS)

flights <- nycflights13::flights
flights<- sample_n (flights, 500)

m1<- glm(formula = arr_delay ~ dep_time + origin+ air_time+ distance , data = flights)
#m1<- glm(formula = arr_delay ~ . , data = flights)

m1<- stepAIC(m1)
  p<- dotwhisker::dwplot(m1)
  z<- p + 
    geom_vline(xintercept=0, linetype="dashed")+
    geom_segment(aes(x=conf.low,y=term,xend=conf.high,
                     yend=term,col=p.value<0.05)) + 
    geom_point(aes(x=estimate,y=term,col=p.value<0.05)) +
  xlab("standardized coefficient") + 
  ylab("coefficient") +
  ggtitle("coefficients in the model and significance")
  print(z)

Answer 1

Your code already kind of does what you want. The problem is that the object p produced by dwplot already has a geom_segment layer and a geom_point layer with a number of aesthetic mappings. Their colors are currently mapped to the variable model, which is just a factor level allowing for different colorings when comparing models side by side. It is possible to over-write them though:

p$layers[[1]]$mapping[5] <- aes(color = p.value < 0.05)
p$layers[[2]]$mapping[4] <- aes(color = p.value < 0.05)

And you can change the legend label with

p$labels$colour <- "Significant"

By default, dwplot also hides the legend, but we can reset that with:

p$theme <- list()

So without adding any new geoms or creating the object z, we have:

p

Note that p is still a valid and internally consistent ggplot, so you can continue to style it as desired, for example:

p + theme_bw() + geom_vline(xintercept = 0, lty = 2)