First get v0.1.6 of yarrr from github

devtools::install_github("ndphillips/yarrr")
library(yarrr)

I’ll use the ChickWeight data and add 10 random points to highlight in the plot

data <- ChickWeight

# Select some random data points to highlight

data$highlight <- FALSE
data$highlight[sample(nrow(data), size = 10)] <- TRUE

Now I’ll create a pointpars dataframe indicating, for each row, some additional parameters for the points depending on whether they are highlighted or not.

# Create custom point parameters depending on whether data is highlighted or not

pointpars <- data.frame(col = ifelse(data$highlight, "red", "black"),                        # highlighted points in red
                        jitter = ifelse(data$highlight, .1, -.1),                            # put highlighted points on right
                        labels = ifelse(data$highlight, rownames(data)[data$highlight], ""), # add labels (just the row name) for highlighted points
                        pos = ifelse(data$highlight, 4, 2),#,             
                        cex.labels = ifelse(data$highlight, .8, 0)
                        )

Here is the default plot (without pointpars)

pirateplot(weight ~ Diet,
           theme = 2,
           data = data)

Here it is with the point parameters

pirateplot(weight ~ Diet,
           data = data,
           theme = 2,
           pointpars = pointpars)

Another version (different theme, exluding custom jitter)

pirateplot(weight ~ Diet,
           theme = 2,
           data = data,
           pointpars = pointpars[, (names(pointpars) != "jitter")])