Create a new column with mutate but using different columns based on condition (if...else statement?)

Question

Let’s say I have a few columns:

life stage (levels: adult, juvenile, larva)
Length of exposure (numeric)
life span (numeric)
age at maturity (numeric)
larval duration (numeric)
dtm (numeric)

I want to calculate some metrics using these in a new column called “proportion.life.duration”. BUT how I calculate (which variables to use) depends on what life stage.

So if life stage == “adult” then I want it to calculate the value in the new “prop.life.duration” column as “length of exposure/ (life span - age at maturity)“.

But if juvenile, I want to calculate using "length of exposure / dtm"; if larvae, I want to calculate as "length of exposure / larval duration"

HOW DO I DO THAT? in R

I thought maybe if..else statements with mutate() but havent figured out how to do that with three levels (adult, juvenile, and larva) AND using different columns to calculate for each.

Can you provide a small subset of your data as example to generate the results you are looking for? — S-SHAAF, Feb 12 '23 at 22:40
Does this answer your question? [Can dplyr package be used for conditional mutating?](https://stackoverflow.com/questions/24459752/can-dplyr-package-be-used-for-conditional-mutating) Especially the `case_when` example in accepted answer. For More `case_when` details and examples you can also check `?case_when` or https://dplyr.tidyverse.org/reference/case_when.html#ref-examples — margusl, Feb 12 '23 at 22:43

score 0 · Answer 1 · answered Feb 13 '23 at 13:48

Try this

library(dplyr)
mydata %>%
  mutate(
    proportion.life.duration = case_when(
      `life stage` == "adult"    ~ `length of exposure` / (`life span` - `age at maturity`),
      `life stage` == "juvenile" ~ `length of exposure` / dtm,
      `life stage` == "larvae"   ~ `length of exposure` / `larval duration`
    )
  )

The backticks around variable names are because the variable names I assume you have contain spaces. If your real column names do not have spaces, you don't need the backticks (as in dtm above).

Create a new column with mutate but using different columns based on condition (if...else statement?)

1 Answers1