Created
November 10, 2017 16:17
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Check for random sampling
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| const assert = require('assert'); | |
| const checks = { | |
| /* original_post: (val, range, maxNum) => { | |
| return val + range - (val % range) < maxNum; | |
| },*/ | |
| traditional: (val, range, maxNum) => { | |
| return val < Math.floor(maxNum / range) * range; | |
| }, | |
| correct: (val, range, maxNum) => { | |
| return val < maxNum - maxNum % range; | |
| }, | |
| }; | |
| const maxNum = 256; | |
| for (let range = 1;range < maxNum;range++) { | |
| const all_counts = {}; | |
| for (const check_name in checks) { | |
| const check = checks[check_name]; | |
| const counts = new Array(range).fill(0); | |
| for (let val = 0;val < maxNum;val++) { | |
| if (check(val, range, maxNum)) { | |
| const res = val % range; | |
| counts[res]++; | |
| } | |
| } | |
| all_counts[check_name] = counts; | |
| for (c of counts) { | |
| if (c !== counts[0]) { | |
| throw new Error( | |
| '[' + check_name + '] Biased for range ' + range + | |
| ': ' + JSON.stringify(counts)); | |
| } | |
| } | |
| } | |
| const ref_counts = all_counts.traditional; | |
| for (const check_name in all_counts) { | |
| const this_counts = all_counts[check_name]; | |
| assert.deepStrictEqual( | |
| this_counts, ref_counts, | |
| 'Counts of ' + check_name + ' incorrect for range = ' + range + ': ' + JSON.stringify(this_counts)); | |
| } | |
| } | |
| console.log('All tests passed'); |
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