R - add a table to a plot

addtable2plot()

• suppose you have a vector with different dates of events and you want to investigates if there are month with more or less events, the first step maybe is to draw a barplot
• so let us generate first a vector with the different dates:
• and than we create a vector with the extracted month (as factor)

my.dat <- as.Date(sample.int(500, 1000, replace=T), origin="2000-01-01") 
# extract month, use the abbreviated form of months
my.months <- months(my.dat, abbreviate=T)
df <- data.frame(date=my.dat, month=my.months)
table(df$month) 

Apr Aug Dez Feb Jan Jul Jun Mai Mär Nov Okt Sep 
122  72  66 103 121  61  51  85 129  59  64  67

• as one can see the month are in alphabetical order so we have to correct this
• therefore we use ISOdatetime and format for creating a vector of the 12 months in the correct order and use this vector for creating a labeled factor out of df$month

df$month <- factor(df$month, levels=format(ISOdatetime(2000,1:12,1,0,0,0),"%b"))
# show the first 50 elements of my.
table(df$month)

Jan Feb Mär Apr Mai Jun Jul Aug Sep Okt Nov Dez 
121 103 129 122  85  51  61  72  67  64  59  66

• now we can create hour barplot (use the package plotrix)

# if it is not installed yet, install it via install.packages("plotrix")
# load the package
library(plotrix) 

# create the table for plotting (the same as above)
my.table <- with(df, table(month)) # equivalent to table(df$month)
# plot it! (choosing the color from here)

barp(my.table, col=colors()[c(462:471,473,477)], xlab="Month", ylab="count")

• now we create the same plot but add the table

# create the table for the plot - i want the horizontal table so i have to transpose it
m2 <- t(as.matrix(my.table)) 
# barplot
barp(my.table, col=colors()[c(462:471,473,477)], xlab="month", ylab="count")
# add the table: the first two arguments are the position relative to the coord system of the plot
# the third argument is the table (a data frame or a matrix), the bty: "o" draw a box, "n" no box
# bg is the argument for the background 
addtable2plot(3,140,m2, bty="o", bg="aliceblue")

now add the table with ggplot2

require(gridExtra)
require(ggplot2)
# generate random dates
my.dat <- as.Date(sample.int(500, 1000, replace=T), origin="2000-01-01") 
# extract month
my.months <- factor(month(my.dat),levels=1:12,labels=month.abb)
df <- data.frame(date=my.dat, month=my.months)

# prepare table
mytable <- tableGrob(t(as.data.frame(table(df$month))),show.rownames = F,show.colnames = F)

ggplot(df,aes(x=month,fill=month)) +
    geom_bar() +
    ylim(0,150) +
    annotation_custom(mytable,xmin = 4.5,xmax=15,ymin=130,ymax = 150) +
    scale_fill_manual(values=colors()[c(462:471,473,477)],guide="none")
ggsave("tabletoplot.png")