\ cancel mode verify
!
! log_key.jnl 
!
! Description : makes a vertical lograthmic color key for shade/fill plots for
!                 given min & max values, variable & viewport(main).  
!                 $6-$10 needs to be adjusted to get the key at the 
!                 required location with required size
!
! Argument      description
! --------      ------------------------------------------------------------
! Mandatory argumnets
! $1 (int)  : lower value of the color key ; should be an integer power(0-4) of 10 
! $2 (int)  : high        "                ;          "           power(1-5) of 10
! $3 (text) : variable to be filled/shaded in double quotes like "rose[d=1]"
!
! Optional arguments
! $4 (text) : name of main view port (like vmain)
! $5 (text) : fill/shade command with qualifiers in double quotes like
!                  "fill/nolab/nokey" (defualt is "fill/nokey")
! $6 (real) : key position : x_low     |  default values of $6-$10 is for making 
! $7 (real) :   "          : x_high    |  a color key of a main viewport defined with
! $8 (real) :   "          : y_low     |  xlim=0:0.96/ylim=0:1 (window aspect=1.0)
! $9 (real) :   "          : y_high    | 
! $10(real) : key size     : text ( /text qualifier to "define view" )
!
! Usage : 
!    go log_key key_low key_high variable [view_main] [fill_command] [key_xlo] [key_xhi] [key_ylo] [key_yhi] [key_txt]
! 
! Example :
!	set data etopo20.cdf
!	set region/x=29.8:120/y=-20.2:50
!	go log_key 1, 10000,"rose[d=1]"   ! <== with minimum argumnets
!               .....OR.....
!   	define view/xlim=0:0.96/ylim=0:1 vmain
!       go log_key 1, 10000,"rose[d=1]",vmain,"fill/nokey/nolab",0.81,1.00,0.10,0.90,0.50
!                                               ! <== with all arguments
!-----------------------------------------------------------------------------------------

! mandatory
   let key_lo = $1"<Usage: go log_key key_low key_high variable [view_main] [fill_command] [key_xlo] [key_xhi] [key_ylo] [key_yhi] [key_txt] "
   let key_hi = $2"<Usage: go log_key key_low key_high variable [view_main] [fill_command] [key_xlo] [key_xhi] [key_ylo] [key_yhi] [key_txt]"
   define symbol var    = $3"<Usage: go log_key key_low key_high variable [view_main] [fill_command] [key_xlo] [key_xhi] [key_ylo] [key_yhi] [key_txt] " 

! optional
   define symbol vmn    = $4"vdummy" 
   define view/xlim=0:0.96/ylim=0:1 vdummy
   define symbol comnd  = $5"fill/pal=blue_darkred/nokey"
   let keyxlo = $6"0.90"  
   let keyxhi = $7"0.999"  
   let keyylo = $8"0.10"  
   let keyyhi = $9"0.90"  
   let keytxt = $10"0.20"  


! consistancy check for the arguments 
       ! this is to make sure that the "levels" needed to make the log color 
       ! key can be safely defined from the given arguments      
           
        let a = log(key_lo) ; let b = log(key_hi) 

        IF `INT(a) LT a` THEN
              say " key_low -> $1 is not an integer power of 10 : correct it "
              exit
        ENDIF 
        IF `INT(b) LT b` THEN
              say " key_high -> $2 is not an integer power of 10 : correct it "
              exit
        ENDIF 
        IF `a GT b` THEN 
              say " key_low{$1} > key_high{$2} : CORRECT key_low & key_high "
              exit
        ENDIF 
        IF `key_lo LT 1` THEN 
              say " with current set up, the possible min value of "
              say "     key_low  is  1  but given value is $1"
              exit
        ENDIF 
        IF `b GT 6` THEN
              say " with current set up, the possible max value of "
              say "     key_high is  100000  but given value is $2"
              exit
        ENDIF

! get the "levels" according to given key_low and key_high 
    ! levs is the possible levels 

        let levs = {'(1,10,1)', '(10,100,10)', '(100,1000,100)', \          
                    '(1E3,1E4,1E3)','(1E4,1E5,1E4)','(1E5,1E6,1E5)'}                                    
       	let lev`a+1` = levs[x=`a+1`]
        IF `a+1 LT b` THEN
	        repeat/i=`a+2`:`b`:1 ( ;\
        	let lev`i` = lev`i-1` + levs[x=`i`] ;\
                )
        ENDIF
        let lev_dummy  = lev`b`         
        define symbol levf = `lev_dummy` 

   ! define the fill command for the main plot as a "symbol"

        define symbol qt   = \"
        define symbol cmnd = (\$comnd)/nolab/lev=(-inf)(\$qt)(\$levf)(\$qt)(inf) (\$var)

! save current reg to "save" & set new reg as required by the key.
   ! the log key will be drawn before the main fill/shade plot. 
  
        define region/default save  
        define reg/x=1:2 kreg 
        set reg kreg

! define a x_axis and log y_axis (y_min is 1 and y_max is 100000)
   ! the data points on y_axis (ie lev_da) should be exactly matching 
   ! with the fill levels defined by levf (ie. levs).

        let lev_da = {1,2,3,4,5,6,7,8,9,10,20,30,40,50,60,70,80,90, \
		  100,200,300,400,500,600,700,800,900,1000,2000,\
		  3000,4000,5000,6000,7000,8000,9000,10000,20000,\
                  30000,40000,50000,60000,70000,80000,90000,100000,\
                  200000,300000,400000,500000,600000,700000,800000,\
                  900000,1000000} 

        define axis/y ydummy=lev_da
        define axis/y key_y=Y[gy=ydummy,y=`key_lo`:`key_hi`]
        def axis/x=1:2:1 key_x 
	let key_da=x[gx=key_x]-x[gx=key_x]+y[gy=key_y]
        define axis/y ylog=LOG(Y[gy=key_y])

! define two viewports with same xlimits,yilmits & text
    ! one vieport will be used for getting tics and labels
    ! other vieport will be used for getting the colors
         
	define view/text=`keytxt`/xlim=`keyxlo`:`keyxhi`/ylim=`keyylo`:`keyyhi` key_v1
	define view/text=`keytxt`/xlim=`keyxlo`:`keyxhi`/ylim=`keyylo`:`keyyhi` key_v2

! tics and numeric lables

        set view key_v1
        ppl axset 0,0,0,1 ; ppl axlabp 0,1; ppl axlsze .25,.25
!        plot/vlog/i=1/nolab/color=white key_da[gy=ylog@asn]

! lograthmic colors 

        set view key_v2
        ppl axlsze 0 0 ; ppl tics 0 0 0 0 0 0; ppl axset 1,1,1,1        
	ppl axlabp -1 -1
!        fill/pal=blue_darkred/set/nolab/nokey/levels=($qt)($levf)($qt) key_da[gy=ylog@asn]
       fill/pal=blue_darkred/set/nolab/nokey/levels=(-inf)($levf)(inf) key_da[gy=ylog@asn]
!        ppl fill

! restore defaults

        ppl axlsze .1,.1 ; ppl tics .125 .25 .125 .25 -1 -1
        cancel reg kreg
        SET REGION save

! get the main fill/shade plot

     ! for labelling or any other needs it is better to have the main viewport
     ! as the active one.

        set view ($vmn)
        ($cmnd)

! cancel defined symbols and variables

  cancel var key* ;   cancel var lev* ; cancel var a ; cancel var b
  cancel symbol cmnd,vmn,var,levf,qt,comnd

! end of log_key.jnl

  set mode/last verify