setting variables with gnuplot's for cycle - bash

Question

I am trying to set variables for gnuplot environment with set for cycle command.
I am using 4.6 version and according the gnuplot documention (page 70) the syntax is following:
for [intvar = start:end{:increment}]
for [stringvar in "A B C D"]
Examples:
set for [i = 1:10] style line i lc rgb "blue"
But i get this error:
gnuplot> set for [var in gpvars] replace(var,'#_#',' ')
^
line 0: Unrecognized option. See 'help set'.
My script:
#!/bin/bash
OUTDIRNAME="out"
TIMEFORMAT='%d.%m.%y'
GPPARS=( "xlabel "Time"" "ylabel "value1"" "y2label "value2"" "format x "%H:%M"")
GPPARS_MOD=()
for (( i=0; i < ${#GPPARS[#]}; i++)); do
FILE=${GPPARS[${i}]}
echo "arg=${FILE}"
GPPARS_MOD+=( "`echo "${FILE}" | sed -e 's/ /#_#/g'`" )
done
gnuplot << EOF
reset
replace(S,C,R)=(strstrt(S,C)) ? \
replace( S[:strstrt(S,C)-1].R.S[strstrt(S,C)+strlen(C):] ,C,R) : S
set terminal png
set output "${OUTDIRNAME}/graph.png"
set timefmt "${TIMEFORMAT}"
set xdata time
gpvars="${GPPARS_MOD[#]}"
set for [var in gpvars] {
replace(var,'#_#',' ')
}
...
EOF
...
exit 0
I am also using function replace, because spaces ( gnuplot ignores escape sequences )The function works flawlessly for plot for cycle.
I have tried with and without function and with variables without spaces, but the result is same.

Answer 1

As a side note -- I'm not sure that I believe your bash array will group things the way you want it to ... for me, your quotations get stripped. try:
GPPARS=( "xlabel 'Time'" "ylabel 'value1'" "y2label 'value2'" "format x '%H:%M'")
instead. (interior double quotes replaced with single quotes)
This is a tricky one -- It's a good thing you're using gnuplot 4.6, otherwise I'm not sure how to go about solving it. (EDIT -- using gnuplot 4.4, you could use a combination of word, words, if, reread, exists and macros, but it's quite a messy solution)
Note that what you have doesn't work because it is akin to:
MYLABEL='xlabel "foo"'
set MYLABEL
Gnuplot doesn't expand MYLABEL prior to doing the set command so that you can do things like:
MYLABEL="totally cool X label here!"
set xlabel MYLABEL
What you want could be accomplished using macros (but alas, not with iteration):
set macro
MYLABEL='xlabel "foo"'
set #MYLABEL
But that doesn't quite work here either because macro expansion happens before anything else (e.g. function evaluation). What you need here is gnuplot's more general iteration introduced in 4.6 combined with eval
do for [ var in gpvars ] {
eval( 'set '.replace(var,'#_#',' ') )
}
EDIT -- gnuplot 4.2+ solution
#top of script -- Nothing should go here.
replace(S,C,R)=(strstrt(S,C)) ? \
replace( S[:strstrt(S,C)-1].R.S[strstrt(S,C)+strlen(C):] ,C,R) : S
if( ! exists("N") ) N=1
TODO="${GPPARS_MOD[#]}"
set macro
do_set=replace(word(TODO,N),'#_#',' ')
set #do_set
N=N+1
if( N <= words(TODO) ) reread
#rest of script here ...