[R] How to switch off accepting the shortcut of column names

[Prof Brian Ripley]

If you had updated your R before posting (as the posting guide suggested) 
you would have found such an option under ?options.  It was new in R 
2.6.0.

On Tue, 30 Oct 2007, P. Olsson wrote:

> Dear R-users,
>
> currently I am working with the R version 2.4.1.
> I realized it has a feature,  which might be wonderful (as so many things in
> R), but in this case might be a bit dangerous as well. It seems that columns
> of a data frame can be called just by indicating the first letter of the
> name of the column.

Well, this applies to lists not just data frame, and to partial matching 
not just the first letter.

If you want only exact matches I suggest you use other operators, e.g.
dat[["f"]] will warn in 2.6.x and fail in R-devel.


> For example:
> first_item <- seq(1,10)
> second_item <- seq(11,20)
> dat <- data.frame(first_item, second_item)
> names(dat)
> # [1] "first_item"  "second_item"
> dat$f
> # [1]  1  2  3  4  5  6  7  8  9 10
> dat$s
> #  [1] 11 12 13 14 15 16 17 18 19 20
>
> The good thing is, that if there is more than one column starting with the
> same letter(s), more than one letter has to be given to call the column.
> However, I would appreciate if I could choose an option in my workspace,
> whether this type of shortcut is allowed or not.
>
> Is there such an option?
>
> Thanks for any potential hints.
>
> Best wishes,
>
> P. Olsson
>
> 	[[alternative HTML version deleted]]
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Please do.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595