Adding secondary x-axis label in ggplot2

Question

I have produced this graph:

It is produced using this code:

ggplot(June, aes(x=Date, y=Count, fill=Species)) + 
  geom_bar(position='dodge', stat='identity') +
  theme(axis.text.x = element_text(angle=90, vjust=0.5))

A sample of the data is here:

structure(list(Day = c("01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "02/06/17", "02/06/17", "02/06/17", "02/06/17", 
"02/06/17", "02/06/17", "02/06/17", "02/06/17", "02/06/17", "02/06/17", 
"02/06/17", "02/06/17", "02/06/17", "02/06/17"), Time = c("20:00", 
"20:00", "20:00", "21:00", "21:00", "21:00", "22:00", "22:00", 
"22:00", "23:00", "23:00", "23:00", "00:00", "00:00", "00:00", 
"01:00", "01:00", "01:00", "02:00", "02:00", "02:00", "03:00", 
"03:00", "03:00", "04:00", "04:00", "04:00", "05:00", "05:00", 
"05:00", "20:00", "20:00", "20:00", "21:00", "21:00", "21:00", 
"22:00", "22:00", "22:00", "23:00", "23:00", "23:00", "00:00", 
"00:00"), Date = c("01/06/17 20:00", "01/06/17 20:00", "01/06/17 20:00", 
"01/06/17 21:00", "01/06/17 21:00", "01/06/17 21:00", "01/06/17 22:00", 
"01/06/17 22:00", "01/06/17 22:00", "01/06/17 23:00", "01/06/17 23:00", 
"01/06/17 23:00", "01/06/17 00:00", "01/06/17 00:00", "01/06/17 00:00", 
"01/06/17 01:00", "01/06/17 01:00", "01/06/17 01:00", "01/06/17 02:00", 
"01/06/17 02:00", "01/06/17 02:00", "01/06/17 03:00", "01/06/17 03:00", 
"01/06/17 03:00", "01/06/17 04:00", "01/06/17 04:00", "01/06/17 04:00", 
"01/06/17 05:00", "01/06/17 05:00", "01/06/17 05:00", "02/06/17 20:00", 
"02/06/17 20:00", "02/06/17 20:00", "02/06/17 21:00", "02/06/17 21:00", 
"02/06/17 21:00", "02/06/17 22:00", "02/06/17 22:00", "02/06/17 22:00", 
"02/06/17 23:00", "02/06/17 23:00", "02/06/17 23:00", "02/06/17 00:00", 
"02/06/17 00:00"), Species = c("Common Pipistrelle", "Soprano Pipistrelle", 
"Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", 
"Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", 
"Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", 
"Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", 
"Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", 
"Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", 
"Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", 
"Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", 
"Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", 
"Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", 
"Common Pipistrelle", "Soprano Pipistrelle"), Count = c(0L, 0L, 
0L, 20L, 0L, 0L, 85L, 0L, 1L, 9L, 0L, 0L, 7L, 0L, 0L, 2L, 0L, 
0L, 1L, 0L, 0L, 5L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 
22L, 0L, 0L, 38L, 0L, 0L, 162L, 2L, 0L, 146L, 5L)), row.names = c(NA, 
-44L), class = "data.frame")

What I would like to do would be to have the hours laid out as they are but with the date as a secondary over arching label which which goes from 00:00 to 23:00 like so:

Is it possible to do this in ggplot2?

Thanks in advance for the help

Please could you kindly replace the presentation of your data with the output of `dput(June)`? — jay.sf, Feb 21 '18 at 01:04
Yes this is possible See this other post for concrete examples: https://stackoverflow.com/questions/39717545/add-secondary-x-axis-labels-to-ggplot-with-one-x-axis — Amar, Feb 21 '18 at 01:33
Possible duplicate of [Add secondary X axis labels to ggplot with one X axis](https://stackoverflow.com/questions/39717545/add-secondary-x-axis-labels-to-ggplot-with-one-x-axis) — Amar, Feb 21 '18 at 01:33

Artem · Accepted Answer · 2018-10-04T20:10:37.257

You can extract hours from Date column by hours function of lubridate package. Prelimenary datetime transformations could be done with this package as well. To put the hours data in a desired order you can use factor function with customized levels argument. Please see the code below:

library(lubridate)    
library(ggplot2)

June <- structure(list(Day = c("01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", "01/06/17", 
"01/06/17", "01/06/17", "02/06/17", "02/06/17", "02/06/17", "02/06/17", 
"02/06/17", "02/06/17", "02/06/17", "02/06/17", "02/06/17", "02/06/17", 
"02/06/17", "02/06/17", "02/06/17", "02/06/17"), Time = c("20:00", 
"20:00", "20:00", "21:00", "21:00", "21:00", "22:00", "22:00", 
"22:00", "23:00", "23:00", "23:00", "00:00", "00:00", "00:00", 
"01:00", "01:00", "01:00", "02:00", "02:00", "02:00", "03:00", 
"03:00", "03:00", "04:00", "04:00", "04:00", "05:00", "05:00", 
"05:00", "20:00", "20:00", "20:00", "21:00", "21:00", "21:00", 
"22:00", "22:00", "22:00", "23:00", "23:00", "23:00", "00:00", 
"00:00"), Date = c("01/06/17 20:00", "01/06/17 20:00", "01/06/17 20:00", 
"01/06/17 21:00", "01/06/17 21:00", "01/06/17 21:00", "01/06/17 22:00", 
"01/06/17 22:00", "01/06/17 22:00", "01/06/17 23:00", "01/06/17 23:00", 
"01/06/17 23:00", "01/06/17 00:00", "01/06/17 00:00", "01/06/17 00:00", 
"01/06/17 01:00", "01/06/17 01:00", "01/06/17 01:00", "01/06/17 02:00", 
"01/06/17 02:00", "01/06/17 02:00", "01/06/17 03:00", "01/06/17 03:00", 
"01/06/17 03:00", "01/06/17 04:00", "01/06/17 04:00", "01/06/17 04:00", 
"01/06/17 05:00", "01/06/17 05:00", "01/06/17 05:00", "02/06/17 20:00", 
"02/06/17 20:00", "02/06/17 20:00", "02/06/17 21:00", "02/06/17 21:00", 
"02/06/17 21:00", "02/06/17 22:00", "02/06/17 22:00", "02/06/17 22:00", 
"02/06/17 23:00", "02/06/17 23:00", "02/06/17 23:00", "02/06/17 00:00", 
"02/06/17 00:00"), Species = c("Common Pipistrelle", "Soprano Pipistrelle", 
"Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", 
"Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", 
"Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", 
"Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", 
"Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", 
"Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", 
"Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", 
"Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", 
"Soprano Pipistrelle", "Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", 
"Big bat sp.", "Common Pipistrelle", "Soprano Pipistrelle", "Big bat sp.", 
"Common Pipistrelle", "Soprano Pipistrelle"), Count = c(0L, 0L, 
0L, 20L, 0L, 0L, 85L, 0L, 1L, 9L, 0L, 0L, 7L, 0L, 0L, 2L, 0L, 
0L, 1L, 0L, 0L, 5L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 
22L, 0L, 0L, 38L, 0L, 0L, 162L, 2L, 0L, 146L, 5L)), row.names = c(NA, 
-44L), class = "data.frame")

June$posix <- dmy_hm(June$Date)
June$Day_2 <- dmy(June$Day)
June$hour <- factor(hour(June$posix), levels = unique(hour(June$posix)))

ggplot(June, aes(x=hour, y=Count, fill=Species)) + 
  geom_bar(position='dodge', stat='identity') +
  theme(axis.text.x = element_text(vjust=0.5)) +
  xlab(paste0(range(June$Day_2), collapse = " - "))

Output:

Adding secondary x-axis label in ggplot2

1 Answers1