How to remove the last character in a string variable in R?-CodePudding

I have subject codes where the last digit of the code is the session number. Using substring I can create a new session number variable, however the session number still needs to be removed from the original subject code. (AN11GR1 should become AN11GR)

Here is a reproducible example with a solution:

structure(list(subject = c("AN11GR1", "AN11GR2", "BR13ST1", "BR13ST2"
), target = c("m_ve", "k_ck", "m_ve", "k_ck"), corrAns = c("o", 
"i", "o", "i"), RT = c(2.9254148, 1.7154148, 2.6454148, 1.9254148
)), class = "data.frame", row.names = c(NA, -4L)) -> myData

myData$session <- substring(myData$subject, nchar(myData$subject))
myData$subject <- substring(myData$subject, 1, nchar(myData$subject)-1)

myData <- subset(myData, select = c(subject, session, RT))
myData

Ideas on how to remove the last character in a concise and convenient way? (For the most concise solution see akrun's comment.)

CodePudding user response：

Add this line to your code. Using substring and nchar you could define to remove the last character:

myData$subject <- substring(myData$subject, 1, nchar(myData$subject)-1)
myData

  subject session       RT
1  AN11GR       1 2.925415
2  AN11GR       2 1.715415
3  BR13ST       1 2.645415
4  BR13ST       2 1.925415