Calculate "distance" between files using compression as metric

filedistance

#!/bin/bash

COMPRESSOR="xz --lzma2=dict="
OVERHEAD=60

if [ -z "$2" ]; then
    echo "Usage: filedistance file1 file2"
    echo "  Outputs similarity metric using between two small files using compression"
    echo "  0 - completely similar; 1 - completely dissimilar"
    exit 1
fi

DICTSIZE=$(cat "$1" "$2" | wc -c)

if [ "$DICTSIZE" -lt 65536 ]; then DICTSIZE=65536; fi

CC="$COMPRESSOR""$DICTSIZE"

A=$(cat "$1" "$1" | $CC | wc -c)
B=$(cat "$2" "$2" | $CC | wc -c)
C1=$(cat "$1" "$2" | $CC | wc -c)
C2=$(cat "$2" "$1" | $CC | wc -c)

#echo "A=$A B=$B C=$C1 $C2"

echo "($C1 + $C2 - $A - $B) / ($A + $B - 2 * $OVERHEAD)" | bc -l

filedistance_multi

#!/bin/bash

FILEDISTANCE=filedistance

if [ -z "$2" ]; then
    echo "Usage: filedistance_multi file1 file2 ... fileN"
    exit 1
fi

FF="$1"

shift;

for i in "$@"; do.
    printf "%s\t%s\t%s\n" $($FILEDISTANCE "$FF" "$i") "$FF" "$i"
done

if [ ! -z "$2" ]; then
    exec "$0" "$@"
fi