gsub用退格替换模式

Question

I have a data set with a column that contains a label with the year ( OldLabel ), and I want to make another column that contains only the label, not the year ( NewLabel ). I wrote the following code, but it leaves a space at the end of the new labels.

data["NewLabel"] <- gsub("20..", "", data$OldLabel)
#removes any part of the OldLabel column that starts with 20 and ends with 2 digits, e.g: 2011 or 2008

Is there a way to have gsub replace the sequence with a backspace, so it gets rid of any spaces around the year it replaces? I tried using "\\\\b" as my replacement text, but that just replaced it with b , not a backspace.

EDIT: Per request, an example of OldLabel would be "Valley Summer 2014" , which should become "Valley Summer" , but ends up being "Valley Summer " with my current code. However, some might also be of the form 2012 Valley Summer , so I don't think simply including a space in the pattern would be robust enough.

Answer 1

Try this:

 data["NewLabel"] <- gsub("[ ]{0,1}20[[:digit:]]{2}[ ]{0,1}", "", data$OldLabel)

The paired curley-braces are repetition quantifiers that have a range determined by either one (exact) or two (min and max) values. See ?regex for more details. (You don't want to replace them with backspace characters.)

test <- c("2012 Valley Summer", "Valley Summer 2014")
gsub("[ ]{0,1}20[[:digit:]]{2}[ ]{0,1}", "", test)
#[1] "Valley Summer" "Valley Summer"

Answer 2

data["NewLabel"] <- gsub("\\s*[0-9]\\s*", "", data$OldLabel)