[R] Regression expression to delete one or more spaces at end of string

[Dennis Fisher]

R 3.3.1
OS X

Colleagues, 

I have encountered an unexpected regex problem

I have read an Excel file into R using the readxl package.  Columns names are:

COLNAMES	<- c("Study ID", "Test and Biological Matrix", "Subject No. ", "Collection Date", 
"Collection Time", "Scheduled Time Point", "Concentration", "Concentration Units", 
"LLOQ", "ULOQ", "Comment”)

As you can see, there is a trailing space in “Subject No. “.  I would like to delete that space.  The following works:
	sub(“ $”, “”, COLNAMES)
However, I would like a more general approach that removes any trailing whitespace.

I tried variations such as:
	sub("[:blank:]$", "", COLNAMES)
(also, without the $ and ‘space' instead of ‘blank') without success — to my surprise, characters other than the trailing space were deleted but the trailing space remained.

Guidance on the correct syntax would be appreciated.

Dennis

Dennis Fisher MD
P < (The "P Less Than" Company)
Phone / Fax: 1-866-PLessThan (1-866-753-7784)
www.PLessThan.com