R - remove anything after comma from column

Question

I'd like to strip this column so that it just shows last name - if there is a comma I'd like to remove the comma and anything after it. I have data column that is a mix of just last names and last, first. The data looks as follows:

Last Name  
Sample, A  
Tester  
Wilfred, Nancy  
Day, Bobby Jean  
Morris  

Answer 1

You can use gsub:

gsub(",.*", "", c("last only", "last, first"))
# [1] "last only" "last"

",.*" says: replace comma (,) and every character after that (.*), with nothing "".

Answer 2

You could use gsub() and some regex:

> x <- 'Day, Bobby Jean'
> gsub("(.*),.*", "\\1", x)
[1] "Day"