incrementing inside a collection

Tue Mar 25 08:07:13 2014 by D

if I have a collection of 6 unsorted values; and I want to increment (+1) a randomly chosen value X amount of times each time independent of one another, what is the most efficient way to do that? most of the ways I've thought of run into problems letting the same value be chosen more than once.

Tue Mar 25 09:30:37 2014 by Torben

I'm not exactly sure what you want to do: Do you want to increment X different values each one time or the same value X times?

If it is the first you want, you can do it like this:

C := {...};  \ your initial collection of 6 values
A := C pick X; \ pick X different values from C
B := C -- A:   \ the remaining (unpicked) values from C
B U (foreach v in A do v+1) \ Add to B the increments of values in A

If you want to pick one value and increment it X times, you can do it like this:

C := {...};  \ your initial collection of 6 values
A := C pick 1; \ pick one value from C
B := C -- A:   \ the remaining (unpicked) values from C
B U (A+X)      \ Add (A+X) to B

Wed Mar 26 01:52:45 2014 by D

X:=3d6 C:={1,2,3,4,5,6}
for every multiple of 4 that X equals or exceeds, I want to add 1 to a randomly chosen value inside C. with the choices being independent of one another. for example

X=13 (so 3 incrementations)
1) 2nd value chosen yields {1,3,3,4,5,6}
2) 6th value chosen yields {1,3,3,4,5,7}
3 2nd value chosen again= {1,4,3,4,5,7}

Wed Mar 26 10:37:25 2014 by Torben

For this, it is best to use a function:

function increment(n,C) =
  if n=0 then C
  else (
    A := C pick 1;
    B := C -- A;
    call increment(n-1, B U (A+1))
  )

call increment((sum 3d6)/4, {1,2,3,4,5,6})

Sun Mar 30 01:05:49 2014 by D

Is there any way to make a variable more persistent? I need to used the identical "sum 3d6" which initiates the function call value again later on for something else; and I need to use the function's modified 6 element collection output later as well. Both of which require a variable that lasts beyond the immediate function, or a very tricky arrangement of parenthesis that I have yet to figure out :P

Mon Mar 31 13:05:17 2014 by Torben

I'm not exactly sure if this is what you want, but you could do something like

x := sum 3d6;
y := call increment(x/4, {1,2,3,4,5,6});
... something that uses x and y ...

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