Expression Miner #improved by tomxor

function u(t) {

c.width=1920 // clear the canvas
for(i=0;i<9;i++)
x.fillRect(400+i*100+S(t)*300,400,50,200) // draw 50x200 rects

} // 122/140

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    u(t) is called 60 times per second.
    t: Elapsed time in seconds.
    S: Shorthand for Math.sin.
    C: Shorthand for Math.cos.
    T: Shorthand for Math.tan.
    R: Function that generates rgba-strings, usage ex.: R(255, 255, 255, 0.5)
    c: A 1920x1080 canvas.
    x: A 2D context for that canvas.

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tomxor

remix of d/18733 by u/joeytwiddle

function u(t) {

D=[5,4,3]
for(i=1e3;i;E=i--%8?E+'X0123456789*/+-&|^~'[(i^i*t)%19]:'')try{D.every((Y,X)=>Y==eval(E))&&(S[E]=1)}catch{}throw Object.keys(S)+E

May 12 2020 11:17 AM UTC

}// 139/140

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Expression Miner #improved

Show more comments…
u/tomxor

1k tests per frame + variable length + deterministic + keeps solution set
u/tomxor

... +4 chars :P
u/tomxor

Struggling to get it to find anything non linear though e.g D=[0,1,2,4,8]
u/tomxor

#fuzzing
u/joeytwiddle

Great, usable! Off of dwitter, this one generates valid syntax from a grammar: https://github.com/joeytwiddle/dweets-dev/bl…
u/tomxor

Interesting. I once wrote an n-card "24 game" solver which is similar but far more limited in terms of operators - by far the most significant optimization i could find was to combinations based on subexpressions that are equivalent to one already traversed i.e nodes in your AST - maybe that could be applied to yours as well?
u/tomxor

* to prune combinations
u/tomxor

oh and the other fairly decent optimization was pruning combinations based on commutativity of binary operators... i.e another kind of equivalence
u/tomxor

I should clarify: to by pruning I mean not mearly skipping evaluation of individual permutations but to be able to skip entire subtrees of permutations by detecting equivalence at the root of that subtree.
u/joeytwiddle

Pruning does sound sensible, but I'm not sure how to approach it.
u/joeytwiddle

I am also having difficultly with >3 non-trivial outputs. I think the search space is too large. But at least I found some simplifications, such as: [1,3,5,7] => X-~X
u/tomxor

Finally got it to solve a non linear one: D=[2,3,6,11,18,27] (2+X*X), just need a bit more patience


      u(t) is called 60 times per second.
      t: elapsed time in seconds.
      c: A 1920x1080 canvas.
      x: A 2D context for that canvas.
      S: Math.sin
      C: Math.cos
      T: Math.tan
      R: Generates rgba-strings, ex.: R(255, 255, 255, 0.5)

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