How to add months to the follow-up missing dates

[Karan]

Hello,

I have a longitudinal data set and I'm struggling to add the missing dates for the follow-up based on the baseline date of visit. Would be great to receive your help.

My code is:

test <- test %>%
group_by(study_id) %>%
filter(Visit == 1) %>% # 1st visit after baseline which is at 6 months
mutate(new_var = if_else(is.na(Follow_up_date), dmy(dateofrandomisation) %m+% month(6),0))

I'm getting the following error: Error in as.POSIXlt.numeric(x) : 'origin' must be supplied

[andresrcs]

Hi, welcome!

We don't really have enough info to help you out. Could you ask this with a minimal REPRoducible EXample (reprex)? A reprex makes it much easier for others to understand your issue and figure out how to help.

If you've never heard of a reprex before, you might want to start by reading this FAQ:

FAQ: How to do a minimal reproducible example ( reprex ) for beginners

A minimal reproducible example consists of the following items: A minimal dataset, necessary to reproduce the issue The minimal runnable code necessary to reproduce the issue, which can be run on the given dataset, and including the necessary information on the used packages. Let's quickly go over each one of these with examples: Minimal Dataset (Sample Data) You need to provide a data frame that is small enough to be (reasonably) pasted on a post, but big enough to reproduce your issue. Let's say, as an example, that you are working with the iris data frame head(iris) #> Sepal.Length Sepal.Width Petal.Length Petal.Width Species #> 1 5.1 3.5 1.4 0.…

[Karan]

Hi,

I have attached an image to better understand the dataset.

Cheers!

Sample|497x284

[andresrcs]

An image is not very helpful, we can't copy from it, and is not a polite thing to do here, please read the guide I gave you and try to make a proper reproducible example.