Subtracting two dates in different formats in R

Question

I'm trying to add a new column with date calculations. The calculation to be entered in the new column is variable MaturityDate minus today's date. MaturityDate in my dataset is in MM/DD/YYYY format and today's date entered with Sys.Date() is in a different format, which I think is what's giving me trouble when calculating. help please!

Make sure both values are proper POSIX date values in R (see `?DateTimeClasses`). Sounds right now like one of them may be a factor or string. But you really need to post a [reproducible example](http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) with sample input data that closely resembles your own so we can see what's going on. — MrFlick, May 06 '15 at 21:32

score 2 · Answer 1 · answered May 06 '15 at 21:58

2

Use package lubridate to make date manipulation easy.

library(lubridate)  
somedate <- mdy("3/14/2015")  
today <- now()  
somedate - today

answered May 06 '15 at 21:58

DaveH

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5

score 0 · Answer 2 · answered May 06 '15 at 21:40

I would convert the dates to a single format to be sure.

date.to.numeric <- function(x) as.numeric(strptime(x,'%m/%d/%Y'))
now <- function() as.numeric(strptime(Sys.Date(),'%Y-%m-%d'))

With this you get time difference in seconds using

date.to.numeric(date) - now()

Also look at as.POSIXct for more date formatting if you wanted something different (e.g., difference in calendar months).

maRtin · Answer 3 · 2015-05-06T22:00:56.067

0

When your dataframe is called YourDataFrame and your new column with the desired result should be called newCol:

YourDataFrame$newCol <- as.Date(MaturityDate, "%m/%d/%Y") - Sys.Date()

edited May 06 '15 at 22:00

answered May 06 '15 at 21:41

maRtin

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11
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Blundering Ecologist · Answer 4 · 2019-05-04T08:21:55.083

Something that works well for me is using a combination of library(dplyr) and library(lubridate)like so:

dataset <-dataset %>% 
    mutate(MaturityDate=mdy(MaturityDate), #make sure to say what the format is first
    Sys.Date=mdy(Sys.Date)) %>%
    mutate(difference=as.numeric(difftime (Sys.Date, MaturityDate, units = "days")))

This gives something like so:

head(dataset,2)

> MaturityDate     Sys.Date     difference
> 2018-05-05      2018-05-26    50
> 2018-06-06      2018-06-10    48

Subtracting two dates in different formats in R

4 Answers4