Adding characters within strings in an R dataframe column

Question

This is the first line of my dataframe (with column names):

site, date, value
TEES, 20000314, 315

As you can see, the dates don't have separators (- or /), so I can't use as.Date . Thus, I need something like this:

TEES, 2000-03-14, 315

How do I do this? Presumably something with sub

Answer 1

Will this work:

as.Date(gsub('(\\d{4})(\\d{2})(\\d{2})','\\1-\\2-\\3',df$date))
[1] "2000-03-14"

Data:

df
  site     date value
1 TEES 20000314   315

Answer 2

You could use the ymd function from the lubridate package. This will automatically add "-" to separate YYYY-MM-DD and convert it to Date .

library(lubridate)

ymd(df$date)

# "2000-03-14"

Answer 3

You can use as.Date you just need to specify the tryFormats argument:

as.Date("20000314", tryFormats = c("%Y%m%d"))
[1] "2000-03-14"

The default is to try these formats: c("%Y-%m-%d", "%Y/%m/%d") , which don't match your current structure so you have to tell it how to read your structure.

Answer 4

We can use anydate from anytime

library(anytime)
anydate("20000314")
#[1] "2000-03-14"