How to create a new variable (column) in my R data frame based on this specific logic?

Question

I have an R data frame and one of its column is a date column in the YYYY-MM-DD format.

Assuming my data frame is called df1 and the date column is called ref.date, how can I create a new column (to be called Category) based on the following logic:

If **ref.date** between `2018-04-01` and `2019-04-01` then **Yr1**

If **ref.date** between `2019-04-01` and `2020-04-01` then **Yr2**

If **ref.date** between `2020-04-01` and `2021-04-01` then **Yr3**

Else **Not Stated**

Any help would be much appreciated.

Note: I had a look at the answers provided in this StackOverflow question but I can't wrap my head around how to implement one of them for my problem:

Case Statement Equivalent in R

Selk · Accepted Answer · 2021-04-12 14:03:19Z

1

The below uses the mutate function from dplyr to make the new column and lubridate to help identify the intervals:

library(dplyr)
library(lubridate)

df1 <- data.frame(
  ref.date = ymd(
    "2020-06-05",
    "2020-03-05",
    "2018-05-12",
    "2015-01-30"
    )
  )


mutate(df1, Category = case_when(
    ref.date %within% interval("2018-04-01", "2019-04-01") ~ "Yr1",
    ref.date %within% interval("2019-04-01", "2020-04-01") ~ "Yr2",
    ref.date %within% interval("2020-04-01", "2021-04-01") ~ "Yr3",
    TRUE ~ "Other"
    ))

answered Apr 12, 2021 at 14:03

Selk

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