LOOKUPZ(Index: v1, v2..v3, etc) : Value what are ranges?

Comments

• AJL Posts: 515

  2021-11-13 22:31

  An example of a range is 12..25 meaning all of the values between 12 and 25 inclusive.
• Bob Drury Posts: 236

  2021-11-13 23:49

  x := 150
  a := 100
  b := 300
  w := lookup(x: A..B) '
  debug(udec(x),udec(y),udec(w) 'w= 249
  x := 50
  a := 100
  b := 300
  w := lookup(x: A..B)
  debug(udec(x),udec(y),udec(w)) 'w= 149
  x := 2
  a := 100
  b := 300
  w := lookup(x: A..B)
  debug(udec(x),udec(y),udec(w)) 'w=101
  If lookupz used instead of lookup the result for above is 250,150,102 not sure how this would ever be used?
• JonnyMac Posts: 8,918

  2021-11-14 06:26

  The lookup functions tend to be used to convert a contiguous range to a non-contiguous range -- the lookupz variant changes the offset of the first element of the list. This example makes that easy to see:

    repeat x from 1 to 5
      y := lookup(x : "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
      term.tx(y)
      term.tx(" ")
  
    term.tx(13)
  
    repeat x from 1 to 5
      y := lookupz(x : "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
      term.tx(y)
      term.tx(" ")
  
    term.tx(13)
  

  The output:
  

  With lookup the search value of zero can be thought of as "don't convert" when used like this:

    if (x)
      x := lookup(x : a..b)
  

  In this case if x is 0 it won't be converted. That said, it can be simplified like this

    x := lookupz(x : x, a..b)
  

  In either case, if x is zero it won't be modified, otherwise it will get set to the xth position within the range of a..b.
• Bob Drury Posts: 236

  2021-11-14 19:52

  thanks i wasn't getting the index to position and i see you can also use arrays within the lookup

  repeat x from 1 to 4
         repeat y from 1 to 9
            w := lookup(x: V1[y],V2[y],V3[y],V4[y])
            debug(udec(x,y,w))
         repeat
  DAT
  V1 long 0,101,102,103,104,105,106,107,108,109
  V2 long 0,201,202,203,204,205,206,207,208,209
  V3 long 0,301,302,303,304,305,306,307,308,309
  V4 long 0,401,402,403,404,405,406,407,408,409
  
• msrobots Posts: 3,704

  2021-11-15 00:01

  that is a new one for me

  cool,

  Mike