Hello all,
I wrote a small function to add labels for outliers in a boxplot.
This function will only work on a simple boxplot/formula command (e.g:
something like boxplot(y~x)).
Code + example follows in this e-mail.
I'd be happy for any suggestions on how to improve this code, for example:
- Handle boxplot.matrix (which shouldn't be too hard to do)
- Handle cases of complex functions (e.g: boxplot(y~a*b))
- Handle cases where there are many outliers leading to a clutter of text
(to this I have no idea how to systematically solve)
Best,
Tal
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# the function
boxplot.add.outlier.text <- function(DATA, x_name, y_name, label_name)
{
boxplot.outlier.data <- function(xx, y_name)
{
y <- xx[,y_name]
boxplot_range <- range(boxplot.stats(y)$stats)
ss <- (y < boxplot_range[1]) | (y > boxplot_range[2])
return(xx[ss,])
}
require(plyr)
txt_to_run <- paste("ddply(DATA, .(",x_name,"), boxplot.outlier.data, y_name
= y_name)", sep = "")
ourlier_df <- eval(parse(text = txt_to_run))
# head(ourlier_df)
txt_to_run <- paste("formula(",y_name,"~", x_name,")")
formu <- eval(parse(text = txt_to_run))
boxdata <- boxplot(formu , data = DATA, plot = F)
boxdata_group_name <- boxdata$names[boxdata$group]
boxdata_outlier_df <- data.frame(group = boxdata_group_name, y =
boxdata$out, x = boxdata$group)
for(i in seq_len(dim(boxdata_outlier_df)[1]))
{
ss <- (ourlier_df[,x_name] %in% boxdata_outlier_df[i,]$group) &
(ourlier_df[,y_name] %in% boxdata_outlier_df[i,]$y)
current_label <- ourlier_df[ss,label_name]
temp_x <- boxdata_outlier_df[i,"x"]
temp_y <- boxdata_outlier_df[i,"y"]
text(temp_x, temp_y, current_label,pos=4)
}
list(boxdata_outlier_df = boxdata_outlier_df, ourlier_df=ourlier_df)
}
# example:
boxplot(decrease ~ treatment, data = OrchardSprays, log = "y", col =
"bisque")
boxplot.add.outlier.text(OrchardSprays, "treatment", "decrease", "colpos")
----------------Contact
Details:-------------------------------------------------------
Contact me: tal.gal...@gmail.com | 972-52-7275845
Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) |
www.r-statistics.com (English)
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