R help - Jun 2001 - Read to the end of a stream (package Rstreams)

Hi there,

I want to read all data from a binary file (with package Rstreams). I
tried the following function (small piece of code):

readdata <- function (file) {
    # open file
    s <- openstream(file, "read")
	
    # read int values 
    while (s$position <= s$size) {
    readint(s, 1, 2) -> type
    [...]
    }

 return()
}

and got the following error:
> Error in while (s$position <= s$size) { : missing value where logical
needed
Is it possible to read data from the start to the finish of a stream?

Thanks,
Sven
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Sven Garbade <garbade at psy.uni-muenchen.de> writes:
> Hi there,
> 
> I want to read all data from a binary file (with package Rstreams). I
> tried the following function (small piece of code):
> 
> readdata <- function (file) {
>     # open file
>     s <- openstream(file, "read")
> 	
>     # read int values 
>     while (s$position <= s$size) {
>     readint(s, 1, 2) -> type
>     [...]
>     }
> 
>  return()
> }
> 
> and got the following error:
> 
> > Error in while (s$position <= s$size) { : missing value where
logical needed
> 
> Is it possible to read data from the start to the finish of a stream?
Yes, but not like that. s does not have the position and size
components; only summary(s) has those. So

while (summary(s)$position < summary(s)$size) {...}

would do it (note: at "==", you're at the end). However, it would
be
more natural to use the fact that readint returns numeric(0) on EOF:

while ( length(type <- readint(s, 1, 2)) )
{
	...
}

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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