How to plot time interval data using ggplot2

ggplot2, r

Solution

Added to your melted data frame two new columns `value2` and `date`. `value2` is `POSIXct` class of your times and `date` column contains just date part of your original `value` and converted to factor to use for faceting.

mdfr$value2<-as.POSIXct(strptime(mdfr$value, "%d/%m/%Y %H:%M:%S"))
mdfr$date<-as.factor(as.Date(strptime(mdfr$value, "%d/%m/%Y %H:%M:%S")))

Now you can use new value2 as x and date for facetting. I used `facet_grid()` with `scales="free_x"` and `space="free_x"` to get evenly spaced time intervals in both facets.

ggplot(mdfr, aes(value2, name)) + 
  geom_line(size = 6) +
  xlab("") + ylab("") +
  theme_bw() + facet_grid(~date,scales="free_x",space="free_x")

Problem

I have a data.frame like this: ``` library(ggplot2) library(reshape2) tasks <- c("Review literature", "Mung data") dfr <- data.frame( name = factor(tasks, levels = tasks), start.date = c("24/08/2010 01:00:01", "24/08/2010 01:00:10", "01/11/2010 01:30:00", "01/11/2010 02:00:00"), end.date = c("24/08/2010 02:00:00", "24/08/2010 03:00:00", "01/11/2010 02:00:00", "01/11/2010 04:00:00") ) mdfr <- melt(dfr, measure.vars = c("start.date", "end.date")) ``` I would like to plot this data using ggplot2 so that different dates are on different facets and only time portion is show on x-axis? I tried something like: ``` ggplot(mdfr, aes(as.Date(value, "%H/%M/%S"), name)) + geom_line(size = 6) + xlab("") + ylab("") + theme_bw() + facet_wrap(~as.Date(value, "%d/%m/%Y")) Error in layout_base(data, vars, drop = drop) : At least one layer must contain all variables used for facetting ```

Original source