Order of dates when plotting time series in R

Question

I would like to know if the order of dates matter when plotting a time series in R.

For example, the dataframe below has it's date starting from the year 2010 onwards increasing as it goes down, for example till 2011:

Date         Number of visits

2010-05-17    13
2010-05-18    11
2010-05-19     4
2010-05-20     2
2010-05-21    23
2010-05-22    26
2011-05-13    14

and below where the year are jumbled up.

Date         Number of visits

2011-06-19   10
2009-04-25   5
2012-03-09   20
2011-01-04   45

Would i be able to plot a time series in R for the second example above? Is it required that in order to plot a time series, the dates must be sorted?

Answer 1

Assuming the data shown reproducibly int he Note at the end create an ordering vector o and then plot the ordered data:

o <- order(dat$Date)
plot(dat[o, ], type = "o")

or convert the data to a zoo series, which will automatically order it, and then plot.

library(zoo)
z <- read.zoo(dat)
plot(z, type = "o")

Note

The data in reproducible form:

Lines <- "Date         Number of visits
2010-05-17    13
2010-05-18    11
2010-05-19     4
2010-05-20     2
2010-05-21    23
2010-05-22    26
2011-05-13    14"
dat <- read.csv(text = gsub("  +", ",", readLines(textConnection(Lines))),
 check.names = FALSE)
dat$Date <- as.Date(dat$Date)

Answer 2

as.Date slove your problem:

data$Date <- as.Date(x$Date)
ggplot(data, aes(Date, Number_of_visits)) + geom_line()