2c:null 2d:["$","title",null,{"children":"Array & bitBuffers | dleeftink | Observable"}] 32:T59c,utfslice = { let arr = Array.from(Array(2**14).keys()) .map(_=> ' ' + crypto.randomUUID() /*+ ' 😀 hello a long real sentence more chars '*/); let t1 = performance.now() let enc = new TextEncoder(); let dec = new TextDecoder(); let len = arr.length * ((' ' + crypto.randomUUID() /*+ ' 😀 hello a long real sentence more chars '*/).length) let dict = {}; let r = new Uint8Array(len) for (var i = 0; i < arr.length; ++i) { var str = arr[i]; const len = str.length; //var dat = new Uint16Array(len); for (var j = 0; j < len-1; ++j) { let lr = str.slice(j,j+2)//str.charCodeAt(j) * str.charCodeAt(j+1) dict[lr] ? dict[lr].push(i) : dict[lr] = [i] //dat[j] = str.charCodeAt(j) } //r.set(dat,i*len) //enc.encodeInto(str, r.subarray((i*len))) //r[i] = enc.encode(str); //r[i] = dec.decode(r[i]); } /*for (let i = 0; i < len-1; ++i) { //str = str + String.fromCharCode(r[i]) let lr = r.subarray(i,i+1) dict[lr] ? dict[lr].push(i) : dict[lr] = [i] } /*arr.map(d=> { let s = new Uint16Array(d.length); for (let i = 0; i < d.length; ++i) { s[i] = d.charCodeAt(i) } return s })*///[...d].map(d=>d.charCodeAt(0))) //str = dec.decode(r); //let r = arr.map(d=>[...d].map(d=>d.charCodeAt(0))) return { r,dict, t: performance.now() -t1 } }33:T703,// densely packed array adapted from: // stackoverflow.com/a/73666335 class BooleanArray { constructor(height, width) { // 2**16 ^ 2 upper limit this.height = height; this.width = width; this.byteWidth = (width >> 3) + ((width & 0b111) > 0 ? 1 : 0); this.dataArray = new Uint8Array(height * this.byteWidth); } getAt(x, y) { const xBytes = x >>> 3; const bitMask = 1 << (x & 0b111); return !!(this.dataArray[y * this.byteWidth + xBytes] & bitMask)|0 // > 0; } setAt(x, y, value) { const xBytes = x >>> 3; const xBits = x & 0b111; const i = y * this.byteWidth + xBytes; if (value) { this.dataArray[i] |= 1 << xBits; } else { this.dataArray[i] &= ~(1 << xBits); } } randomise() { // fills array with integers const size = 2**16 const chunks = (this.dataArray.length/size); for (let i = 0; i < chunks; ++i) { crypto.getRandomValues(this.dataArray.subarray(i*size,(i+1)*size)) } } toString() { let result = ""; for (let y = 0; y < this.height; y++) { result += "\n"; for (let x = 0; x < this.width; x++) { result += this.getAt(x, y) ? "1" : "0"; } } return result; } to2D() { let result = []; for (let y = 0; y < this.height; y++) { result[y] = new Uint8Array(this.width) for (let x = 0; x < this.width; x++) { result[y][x] = this.getAt(x, y) } } return result; } to1D() { let result = new Uint8Array(this.height * this.byteWidth) for (let y = 0; y < this.height; y++) { for (let x = 0; x < this.width; x++) { const xBytes = x >>> 3; const xBits = x & 0b111; result[ y * this.byteWidth + xBytes] = this.getAt(x, y) } } return result; } }34:[] 30:{"id":"7c0f32b5cc944ae3","slug":"array-bitbuffers","title":"Array & bitBuffers","thumbnail":"6f6f4665bdc8844aae1dda06d86c59df9b4223380583b3e3d31c9ee9bf81d06d","access_level":"public","create_time":"$D2023-02-26T03:08:28.710Z","update_time":"$D2024-07-08T16:07:36.525Z","view_time":null,"first_public_time":"$D2023-02-26T03:08:28.710Z","has_unpublished_edits":null,"fork":false,"stars":1,"starred":false,"owner":{"type":"team","id":"10e70264ea4e147e","login":"dleeftink","name":"","avatar_url":"https://avatars-next.observableusercontent.com/3700a558b99f2f54fb2542d09667aadabaae51f24e04e47e420c844503696b0e","tier":"starter_2024"},"version":2031,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"6cdb6324966da5d4","login":"dleeftink","name":"","avatar_url":"https://avatars-next.observableusercontent.com/3700a558b99f2f54fb2542d09667aadabaae51f24e04e47e420c844503696b0e","tier":null}],"members":[{"type":"individual","id":"6cdb6324966da5d4","login":"dleeftink","name":"","avatar_url":"https://avatars-next.observableusercontent.com/3700a558b99f2f54fb2542d09667aadabaae51f24e04e47e420c844503696b0e","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":3,"collection":null,"type":"notebook","body":{"titling":"auto","title":"Array & bitBuffers","cells":[{"id":0,"value":"# Array & bitBuffers\n## encoding different data types","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":10,"value":"___","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":5,"value":"struct = {\n let t1 = performance.now();\n var buf = new ArrayBuffer(24); \n \n var cid = new Uint32Array(buf, 0, 1); \n var num = new Float32Array(buf, 20, 1);\n var str = new Uint8Array(buf, 4, 16); \n\n var initialString = \"A 16 char string\";\n var utf8EncodedString = new TextEncoder(\"utf-8\").encode(initialString);\n\n str.set(utf8EncodedString) \n \n cid[0] = Number.MAX_SAFE_INTEGER\n num[0] = Math.random()\n \n return {\n t:performance.now()-t1,\n buf,cid,str,num,bytes:buf.byteLength\n }\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":860,"value":"bitpack = { \n \n let t1 = performance.now()\n \n let a = BigInt(1); // value to insert (8 bits wide)\n let b = BigInt(2 * (128)); // value to insert (8 bits wide)\n let c = a << 16n; // shift value to index 1 (starts at 8 bits)\n c = c|b; // union a|b, b is now in index 0 (starts at 0 bits)\n \n let size = BigInt(8); // bit width\n let from = BigInt(0); // at 'index'\n \n let pref = BigInt(2) ** size - BigInt(1); // bitmask prefix \n let mask = pref << (from * size); // mask to retrieve 8-bit 'slice'\n let exit = (c & mask) >> (from * size); // resulting value from applying mask\n\n return {\n t: performance.now()-t1,\n a: a.toString(2).padStart(24,0),\n b: b.toString(2).padStart(24,0),\n c: c.toString(2).padStart(24,0),\n c_: c,\n exit\n }\n \n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":1350,"value":"packs = {\n\n let span = 10000\n let nums = Uint16Array.from({length:span},()=>~~(Math.random()*5000))\n \n let pool = BigInt(0), A = BigInt(0), B = BigInt(0);\n let bits = BigInt(8);\n\n let pref = BigInt(2) ** bits - BigInt(1); // bitmask prefix \n\n for (let i = 0; i < span; ++i) {\n\n \n let from = BigInt(nums[i]); // at 'index'\n let post = from * bits; // offset bits\n let mask = pref << (post); // mask to retrieve 8-bit 'slice'\n let exit = ((i % 2 ? A : B) & mask) >> (post); // resulting value from applying mask\n exit = (exit > 255 ? 255 : exit+BigInt(1)) << (post);\n i % 2 ? A |= exit : B |= exit;\n //temp.push(exit) \n }\n\n let t1 = performance.now()\n\n let C = BigInt(0)\n for (let i = 0; i < span; ++i) {\n C = C | (i % 2 ? A : B)\n }\n \n return {\n t:performance.now()-t1,\n r:pool,A:A.toString(2),B:B.toString(2),C:C.toString(2)\n }\n \n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":1833,"value":"BigInt(1) << (BigInt(64) * BigInt(8))","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":1852,"value":"BigInt(1) * (BigInt(1) << BigInt(8*7)) // 72057594037927936n","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":1517,"value":"stress = { // stress test \n\n let span = 5000;\n let dims = 100; // dimensions or 'words'\n\n\n // initialise\n let nums = Array.from({length:span},()=>new Uint16Array(dims))//.from({length:dims}))//,()=>BigInt(~~(Math.random()*Math.random()*10))))\n\n // simulate sparse array;\n for (let i = 0; i < span; ++i) {\n let row = nums[i];\n for (let j = 0; j < dims; ++j) {\n row[j] = (~~(Math.random()*10000)) // generate random indexes\n }\n }\n\n let t1 = performance.now()\n let pool = [];\n let bits = BigInt(8);\n\n for (let i = 0; i < span; ++i) {\n let row = nums[i];\n let mem = BigInt(0);\n\n for (let j = 0; j < dims; ++j) {\n let into = BigInt(row[j]);\n into = BigInt(1) << (bits * into)\n //mem |= into ;\n pool.push(into);\n }\n\n }\n\n return {\n t:performance.now()-t1,\n r:nums,pool\n }\n \n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":867,"value":"plain = {\n\n let span = 1000000\n let nums = Uint16Array.from({length:span},()=>~~(Math.random()*span*0.1))\n let t1 = performance.now()\n\n let dims = new Uint8ClampedArray(span*0.1)\n for (let i = 0; i < span; ++i) {\n let idx = nums[i]\n dims[idx] ? dims[idx]++ : dims[idx] = 1;\n }\n \n let exit = []; span = dims.length;\n for (let i = 0; i < span; ++i) {\n if(dims[i] > 32) exit.push({i,val:dims[i]})\n }\n\n return {\n t:performance.now()-t1,\n r:dims,exit\n }\n \n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":569,"value":"$32","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":17,"value":"___","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":160,"value":"random = { \n let t1= performance.now();\n\n let bitArray = new BooleanArray(2**11, 2**11);\n //bitArray.randomise()\n bitArray.setAt(0,0,1)\n \n let flat = bitArray.to1D()\n let mult = bitArray.to2D()\n return {\n t:performance.now()-t1,\n flat, \n mult, bitArray\n }\n \n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":21,"value":"$33","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":431,"value":"structurae = import('https://cdn.skypack.dev/structurae@4.0.2?min')","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W34","stdlib":"1"}} 31:"$30:body"