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

Bob Drury

LOOKUPZ(Index: v1, v2..v3, etc) : Value
Lookup value (values and ranges allowed) using 1-based index, return value (0 if index out of range)
What are ranges?
Regards and Thanks
Bob (WRD)

AJL

An example of a range is 12..25 meaning all of the values between 12 and 25 inclusive.

Bob Drury

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

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

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

that is a new one for me

cool,

Mike