memDecompress and zlib compressed base64 encoded string

Hi,

I have zlib compressed strings (example is attached)

What is that file? Not gzip compression:

gannet% file compressed.txt
compressed.txt: ASCII text, with very long lines

since gzip uses a magic header that 'file' knows about.  And even if 
the header was stripped, such files are 8-bit and yours is ASCII.
Try

x <- 'Johannes Graumann'
xx <- charToRaw(x)
xxx <- memCompress(xx, "g")
rawToChar(xxx)

[1] "x\x9c\xf3\xca\xcfH\xcc\xcbK-Vp/J,\xcd\0052\001:\n\006\x90"

to see what a real gzipped string looks like.

and would like to decompress them using memDecompress ...

I try this:

connection <- file("compressed.txt","r")
compressed <- readLines(connection)

You have not told us the 'at a minimum' information requested in the 
posting guide.  But you should not expect that to read a binary file, 
especially not in a MBCS locale.  We have readBin for that purpose.

memDecompress(as.raw(compressed),type="g")

I don't think you know what as.raw does: it does not convert bytes in 
a character string to raw (for which you need charToRaw).

It is always a good idea to look at each stage of your computation:

as.raw(compressed)

[1] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00
[26] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00

Error in memDecompress(as.raw(compressed), type = "g") :
 internal error -3 in memDecompress(2)
In addition: Warning messages:
1: In memDecompress(as.raw(compressed), type = "g") :
 NAs introduced by coercion
2: In memDecompress(as.raw(compressed), type = "g") :
 out-of-range values treated as 0 in coercion to raw

Can anyone nudge me into the right direction regarding this?

Thanks, Joh

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