Re: compressing short XML messages without including dictionary or huffman table

On Jun 4, 8:54 am, benedict <benedicth...@xxxxxxxxxxxxxx> wrote:
abcxyz*45 270 => 19 ( 7.0%) :: i.e. no dictionary
abcxyz*45 270 => 22 ( 8.1%) :abc: - why should this
increase the output size?
abcxyz*45 270 => 22 ( 8.1%) :xyz:
abcxyz*45 270 => 19 ( 7.0%) :abcxyz:
abcxyz*45 270 => 20 ( 7.4%) :xyzabc: - suprisingly not
quite the same uas using 'abcxyz'
abcxyz*45 270 => 21 ( 7.8%) :abc xyz: - slightly worse
than 'abcxyz' without the space

So, why is it that specifiying a dictionary can actually increase
output size?

You are looking at extremely small variations in the output size (one
or two bytes), which is not statistically meaningful. In addition,
you are starting with an example that is already highly compressible,
so further gain is rather limited. You should try more realistic
examples, e.g. the XML messages that started the discussion.

Mark

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