Created
October 20, 2023 08:07
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Sequences
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const lettersToSequence = ( | |
letters: string, | |
{startVal = 0, implicitZero = false}: {startVal: number; implicitZero: boolean} = { | |
startVal: 0, | |
implicitZero: false, | |
} | |
) => { | |
const length = letters.length; | |
const letterToIndex = letters.split("").reduce((memo, letter, index) => { | |
memo[letter] = index; | |
return memo; | |
}, {} as {[l: string]: number}); | |
return { | |
intToSeq(intVal: number) { | |
const seq = []; | |
let q = intVal + startVal; | |
if (implicitZero) q += 1; | |
let r; | |
do { | |
if (implicitZero) q += -1; | |
r = q % length; | |
q = Math.floor(q / length); | |
seq.unshift(letters[r]); | |
} while (q); | |
return seq.join(""); | |
}, | |
seqToInt(seq: string) { | |
let intVal = letterToIndex[seq[0]] || 0; | |
for (let i = 1; i < seq.length; i += 1) { | |
if (implicitZero) intVal += 1; | |
intVal *= length; | |
intVal += letterToIndex[seq[i]]; | |
} | |
return intVal - startVal; | |
}, | |
letters, | |
}; | |
}; | |
export const alphaSeq = lettersToSequence( | |
"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" | |
); | |
export const pronounceSafeSeq = lettersToSequence("123456789acefghijkoqrsuvwxyz", { | |
startVal: 28 * 29 - 1, | |
implicitZero: true, | |
}); |
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