[R] avoiding reinstall already installed *package*

(Ted Harding) Ted.Harding at manchester.ac.uk
Tue May 18 18:05:59 CEST 2010

On 18-May-10 15:49:37, Martin Maechler wrote:
> { I've modified the subject; I can't stand it hitting square into
>   my face ... }
>>>>>> "mr" == milton ruser <milton.ruser at gmail.com>
>>>>>>     on Tue, 18 May 2010 12:36:23 -0300 writes:
>     mr> Dear R-experts,
>     mr> I am installing new libraries using
>     mr> install.packages("ggplot2",dependencies=T).
>     mr> But I perceive that many dependencies are already installed.
>     mr> As I am using a low-band internet, how can avoid reinstall
>     mr> installed libraries?
> There's no problem with installed libraries, as ... 
> they DO NOT EXIST.
> These are *PACKAGES* !
> Why do you think are you talking about the function
>  install.packages()  ????
>          ^^^^^^^^

Ah, Martin! I know that "package" is the official terminology,
but R itself tempts the naive user into deviating from the
True Path. Indeed, I had my fingers burned by this myself,
a long time ago (I'm still licking them ... ).

One might ask: "Why do you think we use the function library()?"
when loading add-on packages into R. Indeed, the very directory
tree of R itself stores packages under /usr/lib/R/library.

So, once in a while, someone gets it wrong, and has to find it
out the hard way!

Best wishes,

E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 18-May-10                                       Time: 17:05:57
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