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Random Writer Joe Zachary School of Computing University of Utah.

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Presentation on theme: "Random Writer Joe Zachary School of Computing University of Utah."— Presentation transcript:

1 Random Writer Joe Zachary School of Computing University of Utah

2 Random Writer Based on an idea by Claude Shannon (1948) popularized by A.K. Dewdney (1989) Generates random text based on the patterns in a source file Both fun and appropriate for CS 2 students Uses file input/output, string manipulation, dynamic linear data structures, and random number generation

3 King James Bible For every man putteth one and my mother: for them, to David sent Samson, and a sacrifice. Then went Samson down, and his father and his mother, to Timnath, and came to the vineyards of Timnath: and, behold, a young lion roared against him. Now the ark; and treasures upon them: and, Who also in the evil: so do your heart?

4 King James Bible (Level 6) For every man putteth one and my mother: for them, to David sent Samson, and a sacrifice. Then went Samson down, and his father and his mother, to Timnath, and came to the vineyards of Timnath: and, behold, a young lion roared against him. Now the ark; and treasures upon them: and, Who also in the evil: so do your heart?

5 Tom Sawyer Huck started to act very intelligently on the back of his pocket behind, as usual on Sundays. He was always dressed fitten for drinking some old empty hogsheads. The men contemplated the treasure awhile in blissful silence.

6 Tom Sawyer (Level 8) Huck started to act very intelligently on the back of his pocket behind, as usual on Sundays. He was always dressed fitten for drinking some old empty hogsheads. The men contemplated the treasure awhile in blissful silence.

7 Hamlet Leave heart; for to our lord, it we show him, but skin and he, my lord, I have fat all not over thought, good my lord? Worse that a rat? Dead for a ducat, drugs fit that I bid you not? Ay me, what act, That roars so loud and thunders in the index?

8 Hamlet (Level 5) Leave heart; for to our lord, it we show him, but skin and he, my lord, I have fat all not over thought, good my lord? Worse that a rat? Dead for a ducat, drugs fit that I bid you not? Ay me, what act, That roars so loud and thunders in the index?

9 C++ Programs node *m_pTop; m_pTop = pNext; while (p!=end) res = 0; int temp = A[0]; A[i-1] = A[j]; C[((A[j])>>(shift*8))& 0xff] + 1; int hash code = hash ()(key); float A = (sqrt(5)-1)/2; int index = floor(buckets * (hashcode * A - floor(hashcode * A)));

10 C++ Programs (Level 7) node *m_pTop; m_pTop = pNext; while (p!=end) res = 0; int temp = A[0]; A[i-1] = A[j]; C[((A[j])>>(shift*8))& 0xff] + 1; int hash code = hash ()(key); float A = (sqrt(5)-1)/2; int index = floor(buckets * (hashcode * A - floor(hashcode * A)));

11 Niftiness Not a toy: it slurps up entire books Defies expectations: it turns out to be both straightforward and educational Entertaining: I run a contest to find the funniest generated text

12 Level 0 rla bsht eS ststofo hhfosdsdewno oe wee h.mr ae irii ela iad o r te u t mnyto onmalysnce, ifu en c fDwn oee iteo The probability that c is the next character to be produced equals the probability that c occurs in the source file.

13 Level 1 "Shand tucthiney m?" le ollds mind Theybooure He, he s whit Pereg lenigabo Jodind alllld ashanthe ainofevids tre lin--p asto oun Let s be the previously produced character. The probability that c is the next character to be produced equals the probability that c follows s in the source text.

14 Level K Mr. Welshman, but him awoke, the balmy shore. I'll give him that he couple overy because in the slated snufflindeed structure's Let seed be the previously produced k (4 in this case) characters. The probability that c is the next character to be produced equals the probability that c follows seed in the source text.

15 Algorithm Pick a random k-letter seed from the text Repeatedly: –Make a list of every character that follows the seed in the text –Randomly pick a character c from the text –Output c –Remove the first character from the seed and append c

16 Example at Level 2 Seed: th Text: We hold these truths to be self-evident: that all men are created equal; that they List: [e, s, a, a, e] Character: s (20% of the time) New seed: hs

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