Trying to turn some old ifelse code to case_when

Question

So I have some old ifelse code (below) that I am trying to redo using case_when which I am failrly inexperienced with.

complete_data$type<-ifelse(grepl("Eneg",complete_data$Sample_code),"Negative",
                           ifelse(grepl("PCRneg",complete_data$Sample_code),"Negative",
                                  ifelse(grepl("DNApos",complete_data$Sample_code),"DNApositive",
                                         ifelse(grepl("PCRpos",complete_data$Sample_code),"PCRpositive",
                                         ifelse(grepl("Empty",complete_data$Sample_code),"Empty","Sample")))))

My initial attempt gets the first line working

complete_data$type <- case_when((grepl("Eneg", complete_data$Sample_code) ~ "Negative"))

But then my attempts to get the other ifelse statements in have all failed so far. Would anybody have any suggestions?

Any help would be appreciated

In order for us to help you, please provide a [reproducible example](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example). For example, to produce a minimal data set, you can use `head()`, `subset()`, or the indices. Then use `dput()` to give us something that can be put in R immediately. Also, please make sure you know what to do [when someone answers your question](https://stackoverflow.com/help/someone-answers). More info can be found at Stack Overflow's [help center](https://stackoverflow.com/help). Thank you! — iamericfletcher, Nov 11 '20 at 13:08

score 2 · Answer 1 · answered Nov 11 '20 at 12:30

You can use str_detect/grepl for pattern matching and use case_when in the following way.

library(dplyr)
library(stringr)

complete_data %>%
  mutate(type = case_when(str_detect(Sample_code, 'Eneg|PCRneg') ~ 'Negative', 
                          str_detect(Sample_code, 'DNApos') ~ 'DNApositive', 
                          str_detect(Sample_code, 'PCRpos') ~ 'PCRpositive',
                          str_detect(Sample_code, 'Empty') ~ 'Empty', 
                          TRUE ~ 'Sample')) -> complete_data

score 0 · Accepted Answer · answered Nov 11 '20 at 13:06

0

An alternative without the additional stringr package would be:

libraries("tidyverse")
complete_data <- complete_data %>% mutate(type = case_when(
 grepl("Eneg", Sample_code) | grepl("PCRneg", Sample_code) ~ "Negative",
 grepl("DNApos", Sample_code) ~ "DNApositive"
 grepl("PCRpos", Sample_code) ~ "PCRpositive"
 grepl("Empty", Sample_code) ~ "Empty"
 TRUE ~ "Sample"
))

answered Nov 11 '20 at 13:06

Rotich Titus

63
3

Thank you very much! – Kyle Miller Nov 11 '20 at 15:43

Trying to turn some old ifelse code to case_when

2 Answers2