I am trying to take the difference between two dates in R. Normally, I could have just done this in MS Excel, but I want to try and learn something new by doing this in R. The dates are in the form : Year-Month-Date and are in "factor" format:
# how the data looks like
d <- data.frame (
"day_a" = c("2010-12-25", "2020-10-31"),
"day_b" = c("2011-12-24", "2021-01-01")
)
d$day_a = as.factor(d$day_a)
d$day_b = as.factor(d$day_b)
First, I tried to do a straightforward subtraction :
#my first attempt to take the difference in days
d$day_1 = as.Date(d$day_a, "%Y/%m/%d")
d$day_2 = as.Date(d$day_b, "%Y/%m/%d")
d$diff = d$day_1 - d$day_2
Then, I tried to use the "lubdridate" library:
library(lubridate)
d$diff=interval(ymd(d$day_1),ymd(d$day_2))
However, this also did not work.
Could someone please tell me what I am doing wrong?
Thanks
You need a character input for dates. Also, you were using %Y/%m/%d and you defined in d data as Y-m-d so that the date conversion would work fine:
d <- data.frame (
"day_a" = c("2010-12-25", "2020-10-31"),
"day_b" = c("2011-12-24", "2021-01-01")
)
d$day_a = as.factor(d$day_a)
d$day_b = as.factor(d$day_b)
d$day_1 = as.Date(as.character(d$day_a))
d$day_2 = as.Date(as.character(d$day_b))
d$diff = d$day_1 - d$day_2
Output:
d
day_a day_b day_1 day_2 diff
1 2010-12-25 2011-12-24 2010-12-25 2011-12-24 -364 days
2 2020-10-31 2021-01-01 2020-10-31 2021-01-01 -62 days
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