ggplot2 time series plotting: how to omit periods when there is no data points?

Question

I have a time series with multiple days of data. In between each day there\'s one period with no data points. How can I omit these periods when plotting the time series usin

Answer 1

The problem is that how does ggplot2 know you have missing values? I see two options:

1. Pad out your time series with NA values

2. Add an additional variable representing a "group". For example,

   dd = data.frame(Time, Value)
   ##type contains three distinct values
   dd$type = factor(cumsum(c(0, as.numeric(diff(dd$Time) - 1))))
   
   ##Plot, but use the group aesthetic
   ggplot(dd, aes(x=Time, y=Value)) +
         geom_line (aes(group=type))
   

   gives

   

Answer 2

csgillespie mentioned padding by NA, but a simpler method is to add one NA after each block:

Value[seq(1,length(Value)-1,by=100)]=NA

where the -1 avoids a warning.

Answer 3

First, create a grouping variable. Here, two groups are different if the time difference is larger than 1 minute:

Group <- c(0, cumsum(diff(Time) > 1))

Now three distinct panels could be created using facet_grid and the argument scales = "free_x":

library(ggplot2)
g <- ggplot(data.frame(Time, Value, Group)) + 
  geom_line (aes(x=Time, y=Value)) +
  facet_grid(~ Group, scales = "free_x")