OpenEuphoria

Re: random numbers

• Posted by c.k.lester <euphoric at c?le?ter.com> Nov 22, 2007
• 531 views

Derek Parnell wrote:
> Hey jiri! I knew I should have left it to the master. Your routine is about
> 385% faster than my first try.

Yeah, Jiri's is fast! So, how do you measure randomness?
I know there are tests for it. I'm wondering if jiri's algorithm allows for
every possible permutation. I sped up your original first try, Derek. Look
at shuff3(). But I don't know if that ruins the algorithm or messes with
the randomness.

Here's an updated look:

include misc.e
include get.e

constant fittytwo =
{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52}

sequence tests
	tests = {{},{}}
	
procedure add_test(sequence name, atom id)
	tests[1] = append(tests[1],name)
	tests[2] &= id
end procedure

function shuff1()
sequence s, n
integer r
s = fittytwo
n = repeat(0,52)
for t=1 to 52 do
   r = rand(length(s)) -- grab a random position
   n[t] = s[r] -- add it to our new sequence
   s = s[1..r-1] & s[r+1..$] -- remove from available numbers
end for
return n
end function

function shuff3()
    sequence s, n
    integer r
    s = fittytwo
    n = repeat(0,52)
    for t=52 to 2 by -1 do
     r = rand(t) -- grab a random position
     n[t] = s[r] -- add it to our new sequence
     s[r..51] = s[r+1..52]-- remove from available numbers
    end for
    n[1] = s[1]
    return n
  end function

function shuff4()
    sequence s, n
    integer r
    s = fittytwo
    n = repeat(0,52)
    for t=52 to 2 by -1 do
     r = rand(t) -- grab a random position
     n[t] = s[r] -- add it to our new sequence
s[r..t-1] = s[r+1..t]-- remove from available numbers -- Derek, this is
     what I changed
    end for
    n[1] = s[1]
    return n
  end function

function shuff5()
    object temp
    integer r
    sequence s
    s = fittytwo
    for i = length(s) to 2 by -1 do
        r = rand(i)
        temp = s[r]
        s[r] = s[i]
        s[i] = temp
    end for
    return s
end function

procedure run_tests()
atom c, t
sequence test
integer secs

for x=1 to length( tests[1]) do
	c=0
	secs = 1
	
	puts(1,"Starting test " & tests[1][x] & "\n")
	
	t = time() + secs
	while t > time() do
		test = call_func(tests[2][x],{})
		c += 1
	end while
	?test
	printf(1,"\t%d\n\n",{c})
end for

end procedure

add_test("Baseline",routine_id("shuff1"))
add_test("Derek's First",routine_id("shuff3"))
add_test("Derek's First Modified",routine_id("shuff4"))
add_test("Jiri's Speed Demon",routine_id("shuff5"))

run_tests()

puts(1,"\nDone! Press any key to quit.")
if wait_key() then end if