Re: [R] dir() and RegEx and gsub()

From: Uwe Ligges <ligges_at_statistik.uni-dortmund.de>
Date: Fri 10 Jun 2005 - 21:01:36 EST

Hans-Peter wrote:

> 2005/6/9, Sarah Goslee <sarah.goslee@gmail.com>:
>
>

>>Under R, for reasons I've never quite understood,
>>"\\." evaluates to .

>
>
> Thanks to the answers of B. Ripley and Gabor I think, I understand now:
>
> 1) the patter-string "\\.csv$" gives the regular expression "\.csv$"
> 2) now the backslash lets the dot to be interpreted literally
> (instad of a metacharacter). As said by Gabor, an alternative is,
> to put the dot between brackets
>
>
>>If you mean you want to change the "\" to either "\\" or "/" I'm
>>really not sure.

>
>
> Yes that's what I intended.
> Because in windwos I copy the path from the address bar of the
> explorer and paste it in the R console window. Now I *have* something
> like
> myfile <- "D:\UebungenNDK\DataMining\DataMiningSeries.r"
 > that needs to be adjusted manually ;-(

Copy and try

   myfile <- readLines("clipboard")

> I interpret the answers
>
>

>>>myfile <- "D:\UebungenNDK\DataMining\DataMiningSeries.r"
>>
>>I am sure that's not what you intended.  It has to be written as
>>[snip] [1]  "D:/UebungenNDK/DataMining/DataMiningSeries.r"

>
>
> and
>
>
>>>myfile <- "D:\UebungenNDK\DataMining\DataMiningSeries.r"
>>
>>Variable myfile, as you have written it above, has no backslashes in it
>>so there is no way way to know where they are supposed to be. 

>
>
> that it's not possible at all to have a character string with
> backslashes in it (because they *will* act as escape characters).

It *is* possible to *have* such a character string,

   x <- "a\\b"
generates an x that contains a *single* backslash. It's a matter of parsing.

> - Maybe I could get along by writing an *external* function that would
> give me back a proper formatted path, eg.
> fold <- as.path( "D:\UebungenNDK\DataMining\DataMiningSeries.r" )
> [1] "D:/UebungenNDK/DataMining/DataMiningSeries.r"
>
> - But then the behaviour would be different from all the other strings
> in R which doesn't seem to be a good idea either
>
>

>>I've always just processed the strings in vim or similar, rather

>
> than fight with R.
>
> I do it in DOS-Batch files. Quite ugly but it works...
>
>
> Regards,
> Hans-Peter
>
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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jun 10 21:07:12 2005

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