regex - 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 could use gsub() and some regex:

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