Create a new variable based on the first 7 characters of existing variable

Question

I've been struggling to create a new variable which contains only the first seven characters of an existing variable. Sorry if this if obvious but I've struggled to find an answer which meets my needs on Google/Stack Overflow.

My data looks like this:

variable
UKM5001028
UKM5001028
UKM5001028
UKM5001028

I want to have:

variable2
UKM5001
UKM5001
UKM5001
UKM5001

I tried the below code and succeeded in trimming at the 7th character, but it tried to print the whole output, when I want to make a new variable:

variable2<-mydata$variable
substr(variable2, 1, 7)

Answer 1

You are passing wrong argument to substr

Try

variable2 <- substr(mydata$variable,1,7)

Answer 2

You need to store the output of substr(variable2, 1, 7) into variable2. Currently you're printing only

variable2<-mydata$variable
variable2<-substr(variable2, 1, 7)