Around 1974 or so I attended a lecture by a Yale professor about monkeys: if you have a room full of monkeys, each banging on a typewriter, eventually you’ll get all of Shakespeare’s works. Using a random number generator to generate characters simulates this process with fewer bananas required.

Of course, not all letters occur with the same frequency. If the typewriter noticed that the monkey typed a “Q”, then it could force the next letter to be “U” with a particular probability. Similarly for other letter pair combinations. One can imagine using some existing text as a model from which to calculate frequencies of letter pairs. How often is “t” followed by “h” ? by “a” ? One can also imagine that extrapolating such 2 letter patterns to n letter patterns can produce even better results.

I wrote a program in C about 20 years ago to simulate the monkeys. I wrote it again in VFP, and found it surprisingly simple to write.

This program can be used on other text, such as programs, or different languages, such as German.

Try experimenting with different pat lengths.

WarAndPeace.Txt can be found at http://www.calvinhsia.com/vfp/monkeys.asp

CLEAR ALL
CLEAR

nPatLen=18
CREATE CURSOR letters (chrs c(nPatLen), cnt i)
INDEX ON chrs tag chrs
fd=FOPEN("warandpeace.txt")
*fd=FOPEN("genmenu.prg")
IF fd <0
	?"err opening file"
	RETURN 
ENDIF 
cprior=""
nCnt=0
do while !FEOF(fd) and !CHRSAW() and nCnt<100000
	ch=FREAD(fd,1)
	nAsc=ASC(LOWER(ch))
	IF (nAsc>96 and nAsc <=122) or nAsc=32 or nasc=13 or nasc=10
		nCnt=nCnt+1
		IF LEN(cprior) >= nPatLen
			cprior=SUBSTR(cprior,2)+ch
			IF SEEK(cprior)
				REPLACE cnt with cnt+1
			ELSE 
				INSERT into letters values (cprior,1)
			ENDIF 
		ELSE
			cprior=cprior+ch
		ENDIF 
	ENDIF 
ENDDO
FCLOSE(fd)
LOCATE 
BROWSE last nowa
ACTIVATE WINDOW (PROGRAM())
GO INT(RAND()*RECCOUNT()+1)
cPrior=chrs
do while !CHRSAW()
	cLast=SUBSTR(cPrior,2)
	SEEK cLast
	SUM  cnt while chrs = cLast to nCnt
	nr=INT(RAND()*nCnt+1)
	SEEK cLast
	SCAN while nr >0
		nr=nr-cnt
	ENDSCAN 
	SKIP -1
	cNewLet=RIGHT(chrs,1)
	??cNewLet
	cPrior=SUBSTR(cPrior,2)+cNewLet
ENDDO
INKEY()