cc: [email protected]
Subject: Re: [ast-users] Sort a very large array of compound variables?
--------
In order to get good performance with sorting > 10M elements
of a compound variable, I will have to add a another option to
ksh93.
I was thinking of adding a -K option to set which can be
used with -s to sort on keys of a compound variable array.
The -K options can take a comma separated list of key fields
each one optionaly followed by :n to indicate a numerical
sort.
Here is a function that will sort a compound variable on
a single key, but it takes a few minutes just for 1 million
compound elements to sort.
======================cut here====================
function carray_sort # comvar keyfield delim sort_opts
{
trap 'rm -f /tmp/shsort[12].$$' EXIT
nameref var=$1
nameref key=$2
typeset delim=$3
typeset v smallest=
integer i max=${#var[@]}
[[ $4 == *-n* ]] && ((smallest=-9e999))
print -- "$smallest&${!var}=(" > /tmp/shsort1.$$
for((i=0;i < max; i++))
do v=$(typeset -p var[$i])
print -r -- "${var[i].key}$delim${v#*=}"
done >> /tmp/shsort1.$$
sort -t"$delim" $4 -k1.1 /tmp/shsort1.$$ | cut -f2- -d$delim >
/tmp/shsort2.$$
print ')' >> /tmp/shsort2.$$
. /tmp/shsort2.$$
}
# here is a sample compound array with 1 million elements
integer i
float x=.1
compound -a c
for ((i=0; i < 1000000; i++))
do ((x += .1 ))
c[i]=(key=$((sin(x))) index=$((i+7)) )
done
carray_sort c key '&' -n
======================cut here====================
David Korn
[email protected]
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