Here's how it can be done in Ruby, might give you some ideas for Perl:
---
require 'zlib'
NETWORK_FLOAT = 'g*'
NETWORK_DOUBLE = 'G*'
LITTLE_ENDIAN_FLOAT = 'e*'
LITTLE_ENDIAN_DOUBLE = 'E*'
BASE_64 = 'm*'
def unpack_mzxml_string(str, precision=32, network_order=true,
compressed=false)
unpack_code =
case precision
when 32 ; network_order ? NETWORK_FLOAT : LITTLE_ENDIAN_FLOAT
when 64 ; network_order ? NETWORK_DOUBLE :
LITTLE_ENDIAN_DOUBLE
else
raise ArgumentError, "unknown precision (should be 32 or
64): #{precision}"
end
binary = str.unpack("#{BASE_64}").first
binary = Zlib::Inflate.inflate(binary) if compressed
binary.unpack(unpack_code)
end
---
This is an exerpt from a simple command line program:
http://gist.github.com/406601
It is modified from ms-core: lib/ms/data/lazy_io.rb [co-authored with
Simon Chiang]
http://github.com/jtprince/ms-core
On Apr 8, 10:52 am, jcmatese <[email protected]> wrote:
> Hi All,
>
> Is there a documentation or recipe for decoding zlib compressed peaks
> for mxXML version 3.1? I had been using a variation of a perl recipe
> provided byZackBoothSimpsonand John Prince, documented
> here:http://sashimi.sourceforge.net/schema_revision/mzXML_2.1/Doc/mzXML_2....
>
> However, it does not account for compressionType="zlib" and
> compressedLen attributes.
>
> I cannot find much documentation on 3.1 (and compressionType and
> compressedLen). I presume that one would just take the peaks-as-text
> string and inflate it (using some zlib package from CPAN, presumably)
> prior to decoding base64.
>
> Does anyone have a favorite recipe or a pointer to documentation
> similar to the 2.1 tutorial above (a tutorial for mzXML 3.1)?
>
> Thanks,
> John
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