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June 2018 Update

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Ingy döt Net 2018-06-22 20:57:24 +00:00
parent ba8067c3b7
commit 22f33d4004
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Task/Knuths-algorithm-S/REXX/knuths-algorithm-s.rexx
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@ -1,40 +1,39 @@
/*REXX program using Knuth's algorithm S (a random sampling N of M items).*/
parse arg trials size . /*obtain optional arguments from the CL*/
if trials=='' then trials=100000 /*Not specified? Then use the default.*/
if size=='' then size= 3 /* " " " " " " */
#.=0 /*initialize frequency counter array. */
do trials /*OK, now let's light this candle. */
call s_of_n_creator size /*create an initial list of N items. */
/*REXX program using Knuth's algorithm S (a random sampling N of M items). */
parse arg trials size . /*obtain optional arguments from the CL*/
if trials=='' | trials=="," then trials=100000 /*Not specified? Then use the default.*/
if size=='' | size=="," then size= 3 /* " " " " " " */
#.=0 /*initialize frequency counter array. */
do trials /*OK, now let's light this candle. */
call s_of_n_creator size /*create an initial list of N items. */
do gener=0 for 10
call s_of_n gener /*call s_of_n with a single decimal dig*/
end /*gener*/
do gener=0 for 10
call s_of_n gener /*call s_of_n with a single decimal dig*/
end /*gener*/
do count=1 for size /*let's examine what SofN generated. */
_=!.count /*get a decimal digit from the Nth */
#._=#._+1 /* ··· item, and count it, of course.*/
end /*count*/
end /*trials*/
@='trials, and with size='
say "Using Knuth's algorithm S for" commas(trials) @ || commas(size)":"
say
do dig=0 to 9 /* [↓] display the frequency of a dig.*/
say left('',20) "frequency of the" dig 'digit is:' commas(#.dig)
end /*dig*/
exit /*stick a fork in it, we're all done. */
/*────────────────────────────────────────────────────────────────────────────*/
commas: procedure; parse arg _; n=_'.9'; #=123456789; b=verify(n,#,"M")
e=verify(n, #'0', , verify(n, #"0.", 'M')) - 4
do j=e to b by -3; _=insert(',',_,j); end /*j*/; return _
/*────────────────────────────────────────────────────────────────────────────*/
s_of_n: parse arg item; items=items+1 /*get "item", bump the items counter.*/
c=random(1, items) /* [↓] should replace a previous item?*/
if c>size then return /*probability isn't good, so skip it. */
_=random(1, size); !._=item /*now, figure out which previous ··· */
return /* ··· item to replace with ITEM.*/
/*────────────────────────────────────────────────────────────────────────────*/
s_of_n_creator: parse arg item 1 items /*generate ITEM number of items. */
do k=1 for item /*traipse through the first N items. */
!.k=random(0, 9) /*set the Kth item with random digit.*/
end /*k*/
return /*the piddly stuff is done (for now). */
/* [↓] examine what SofN generated. */
do count=1 for size; _= !.count /*get a dec. digit from the Nth item. */
#._=#._ + 1 /*bump counter for the decimal digit. */
end /*count*/
end /*trials*/
@= ' trials, and with a size of '
hdr=" Using Knuth's algorithm S for " commas(trials) @ || commas(size)": "
say hdr; say copies("═", length(hdr) ) /*display the header and its separator.*/
do dig=0 to 9 /* [↓] display the frequency of a dig.*/
say left('', 20) "frequency of the" dig 'digit is: ' commas(#.dig)
end /*dig*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
commas: parse arg _; do jc=length(_)-3 to 1 by -3; _=insert(',', _, jc); end; return _
/*──────────────────────────────────────────────────────────────────────────────────────*/
s_of_n: parse arg item; items=items + 1 /*get "item", bump the items counter.*/
c=random(1, items) /* [↓] should replace a previous item?*/
if c>size then return /*probability isn't good, so skip it. */
_=random(1, size); !._=item /*now, figure out which previous ··· */
return /* ··· item to replace with ITEM.*/
/*──────────────────────────────────────────────────────────────────────────────────────*/
s_of_n_creator: parse arg item 1 items /*generate ITEM number of items. */
do k=1 for item /*traipse through the first N items. */
!.k=random(0, 9) /*set the Kth item with random digit.*/
end /*k*/
return /*the piddly stuff is done (for now). */