irfuncs.js

function vb(n) {
	var binary = n.toString(2);
	var expectedLength = Math.ceil(binary.length / 7) * 7; // works
	var sevenByteBlocks = binary.padStart(expectedLength, '0').match(/\d{7}/g);
	var lastElemIdx = sevenByteBlocks.length - 1;
	for (var i = 0; i < lastElemIdx; i++) {
		sevenByteBlocks[i] = '0' + sevenByteBlocks[i];
	}
	sevenByteBlocks[lastElemIdx] = '1' + sevenByteBlocks[lastElemIdx];
	return sevenByteBlocks.join('');
}

function unary(n) {
	return '0'.padStart(n + 1, '1');
}

function gamma(n) {
	var bin = n.toString(2);
	return unary(bin.length - 1) + bin.substring(1, );
}

function fMeasure(p, r) { return 2 * p*r/(p + r); }
function prec(tp, fp) { return tp / (tp + fp); /* fp is what we did return but musn't have */ }
function rec(tp, fn) { return tp / (tp + fn); /* fn is what we must have returned but didn't  */ }

function ct(r_cont, n_cont, r_mis, n_mis, base=10) {
	var	log_func = getLogFunc(base);
	if(log_func === null) {return;}

	// N = r_cont + n_cont + r_mis + n_mis; // 2 for 1/2s later
	// DFt = (r_cont + n_cont) / N;
	// S_s = r_mis;
	// s = r_cont;


	return log_func ( (r_cont / r_mis) / (n_cont / n_mis) );
}


function getLogFunc(base) {

	switch(base) {
		case 2:
			console.log("using log2");
			return Math.log2;

		case 10:
			console.log("using log10");
			return Math.log10;
			
		case "n":
			console.log("using log");
			return Math.log;
		
		default:
			console.log("invalid base");
			return null;
	}
}


function soundex(word) {
	
	encoded = "";
	for (let i = 1; i < word.length; i++) {
		const element = word[i];
		encoded += encode(word[i]);
	}

	console.log('encoded is ' + encoded);
	

	res = word[0];
	curr_char = "~";
	for(let i = 0; i < encoded.length - 1; i++) {

		if(encoded[i] != curr_char) {
			curr_char = encoded[i];
			res += encoded[i];
		}
	}

	if(res.length >= 4) {
		return res.substring(0, 4);
	} else {
		diff = 4 - res.length;
		return res.padEnd(diff, "0")
	}
}

function encode(ch){
	
	if("a e i o u y h w".indexOf(ch) > -1) {
		return 0;
	}

	if("b, f, p, v".indexOf(ch) > -1) {
		return 1;
	}

	if("c, g, j, k, q, s, x, z ".indexOf(ch) > -1) {
		return 2;
	}

	if("d, t".indexOf(ch) > -1) {
		return 3;
	}

	if('l'.indexOf(ch) > -1) {
		return 4;
	}

	if('m, n'.indexOf(ch) > -1) {
		return 5;
	}

	if('r'.indexOf(ch) > -1) {
		return 6;
	}

	console.log('wrong char');
	return null;
}