How do I open R help about a symbol or punctuation mark like ( parenthesis or [ bracket?

April 8, 2014
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(This article was first published on isomorphismes, and kindly contributed to R-bloggers)

A question I’ve googled before without success. Hopefully this answer will show up for someone who needs it. I’ll also go over the better-known uses of ? just in case.

  • To get help in R about a function like subset you type ?subset . That’s like man subset from the command line.
  • If you only know roughly what you’re looking for use double question marks: so ??nonlinear will lead to the package nlme. That’s like apropos on the command line.
  • To get a package overview, type ?xts::xts. There does not exist ?xts help. Packages that don’t have ?twitteR::twitteR you will need to use ??twitteR to find the help pages on ?twitteR::status-class, ?twitteR::dmGet, etc.
  • Finally, the question of the title. To get R help on punctuation such as (, {, [, `, ::, ..., +, and yes, even on ? itself, use single quotes to ‘escape’ the meaningful symbol. Examples follow:
    • ?'`'
    • ?'('
    • ?'['
    • ?'...'
    • ?'+'
    • ?'%*%'
    • ?'%x%'
    • ?'%o%'
    • ?'%%'
    • ?'%/%'
    • ?'$'
    • ?'^'
    • ?'~'
    • ?'<-'
    • ?'='
    • ?'<<-'

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