How to use Ferret "constant arrays" (e.g. "{1,3,5}")

Below is an annotated version of the script constant_array_demo.jnl

! constant_array_demo.jnl (4/99)

! Description: Demonstration of the {1, 3, 5} "constant array" syntax

! Constant array syntax introduced into Ferret in V5.0

! Constant arrays allow you quickly to enter lists of constant values.

! SYNTAX:
! Constant arrays are comma-separated lists enclosed in curly braces.
! If the list needs to contain gaps (missing values), simply omit the element
! For example

  LIST {1,3,5}, {1,,5}

        
 yes? LIST {1,3,5}, {1,,5}
 X: 0.5 to 3.5
 Column  1: {1,3,5}
 Column  2: {1,,5}
        {1,3,5} {1,,5} 
1   / 1:   1.000  1.000
2   / 2:   3.000   ....
3   / 3:   5.000  5.000



  





! Note that a constant variable is always an array oriented
in the X direction

! To create a constant aray oriented in, say, the Y direction
use YSEQUENCE



  STAT/BRIEF YSEQUENCE({1,3,5})




  

    

      
        
 yes? STAT/BRIEF YSEQUENCE({1,3,5})


        
 Total # of data points: 3 (1*3*1*1)
 # flagged as bad  data: 0
 Minimum value: 1
 Maximum value: 5
 Mean    value: 3 (unweighted average)

      		
    

  



 



! EXAMPLES

! Below are several examples illustrating uses of constant arrays

! 1) plots a triangle

! 2) plots a series of triangles at data points

! 3) Samples a variable at a list of subscripts



! Ex 1) plot a triangle



  LET xtriangle = {0,.5,1}
  LET ytriangle = {0,1,0}
  POLYGON/LINE=8 xtriangle, ytriangle, 0




  
 
    


  

    

  





! Ex 2) plot a series of triangles at data points

! See also XXXX.jnl for a more automated way to do this)



  LET xpts = 10*RANDU(j[j=1:20]+0)	! random X coordinates
  LET ypts = 10*RANDU(j[j=1:20]+1)	! random Y coordinates
  LET values = 10* j[j=1:20]		! value at each (x,y) point
  POLYGON xpts+xtriangle, ypts+ytriangle, values




  
 








! Ex 3) Sample winter and summer in the Northern hemisphere
from sst in coads_climatology



  USE coads_climatology
  LET my_sst_winter = SAMPLEL({1,2,12}, sst[Y=0:90N])
  LET my_sst_summer = SAMPLEL({6,7,8},  sst[Y=0:90N])
  STAT/BRIEF my_sst_winter
  STAT/BRIEF my_sst_summer




  

        
 yes? STAT/BRIEF my_sst_winter



        Total # of data points: 24300 (180*45*1*3)

        # flagged as bad data: 12310

        Minimum  value:   -2.2

        Maximum value:  29.513

        Mean        value: 17.703          (unweighted
        average) 


        
yes? STAT/BRIEF my_sst_summer



        Total # of data points: 24300 (180*45*1*3)

        # flagged as bad data: 11094

        Minimum  value:  -2.3

        Maximum value: 33.15

        Mean       value: 19.648          (unweighted
        average)







 
oar.pmel.contact_ferret@noaa.gov 
5 Apr, 1999