data-structure-typed/test/utils/big-o.ts

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import {AnyFunction} from '../types';
import {isDebugTest} from '../config';
const isDebug = isDebugTest;
const orderReducedBy = 2; // reduction of bigO's order compared to the baseline bigO
export const magnitude = {
CONSTANT: Math.floor(Number.MAX_SAFE_INTEGER / Math.pow(10, orderReducedBy)),
LOG_N: Math.pow(10, 9 - orderReducedBy),
LINEAR: Math.pow(10, 6 - orderReducedBy),
N_LOG_N: Math.pow(10, 5 - orderReducedBy),
SQUARED: Math.pow(10, 4 - orderReducedBy),
CUBED: Math.pow(10, 3 - orderReducedBy),
FACTORIAL: 20 - orderReducedBy
};
export const bigO = {
CONSTANT: magnitude.CONSTANT / 100000,
LOG_N: Math.log2(magnitude.LOG_N) / 1000,
LINEAR: magnitude.LINEAR / 1000,
N_LOG_N: (magnitude.N_LOG_N * Math.log2(magnitude.LOG_N)) / 1000,
SQUARED: Math.pow(magnitude.SQUARED, 2) / 1000,
CUBED: Math.pow(magnitude.SQUARED, 3) / 1000,
FACTORIAL: 10000
};
function findPotentialN(input: any): number {
let longestArray: any[] = [];
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let mostProperties: {[key: string]: any} = {};
function recurse(obj: any) {
if (Array.isArray(obj)) {
if (obj.length > longestArray.length) {
longestArray = obj;
}
} else if (typeof obj === 'object' && obj !== null) {
const keys = Object.keys(obj);
if (keys.length > Object.keys(mostProperties).length) {
mostProperties = obj;
}
keys.forEach(key => {
recurse(obj[key]);
});
}
}
if (Array.isArray(input)) {
input.forEach(item => {
recurse(item);
});
} else {
recurse(input);
}
// return [longestArray, mostProperties] : [any[], { [key: string]: any }];
return Math.max(longestArray.length, Object.keys(mostProperties).length);
}
function linearRegression(x: number[], y: number[]) {
const n = x.length;
const sumX = x.reduce((acc, val) => acc + val, 0);
const sumY = y.reduce((acc, val) => acc + val, 0);
const sumXSquared = x.reduce((acc, val) => acc + val ** 2, 0);
const sumXY = x.reduce((acc, val, i) => acc + val * y[i], 0);
const slope = (n * sumXY - sumX * sumY) / (n * sumXSquared - sumX ** 2);
const intercept = (sumY - slope * sumX) / n;
const yHat = x.map(val => slope * val + intercept);
const totalVariation = y.map((val, i) => (val - yHat[i]) ** 2).reduce((acc, val) => acc + val, 0);
const explainedVariation = y.map(val => (val - sumY / n) ** 2).reduce((acc, val) => acc + val, 0);
const rSquared = 1 - totalVariation / explainedVariation;
return {slope, intercept, rSquared};
}
function estimateBigO(runtimes: number[], dataSizes: number[]): string {
// Make sure the input runtimes and data sizes have the same length
if (runtimes.length !== dataSizes.length) {
return 'Lengths of input arrays do not match';
}
// Create an array to store the computational complexity of each data point
const complexities: string[] = [];
// Traverse different possible complexities
const complexitiesToCheck: string[] = [
'O(1)', // constant time complexity
'O(log n)', // Logarithmic time complexity
'O(n)', // linear time complexity
'O(n log n)', // linear logarithmic time complexity
'O(n^2)' // squared time complexity
];
for (const complexity of complexitiesToCheck) {
// Calculate data points for fitting
const fittedData: number[] = dataSizes.map(size => {
if (complexity === 'O(1)') {
return 1; // constant time complexity
} else if (complexity === 'O(log n)') {
return Math.log(size);
} else if (complexity === 'O(n)') {
return size;
} else if (complexity === 'O(n log n)') {
return size * Math.log(size);
} else if (complexity === 'O(n^2)') {
return size ** 2;
} else {
return size ** 10;
}
});
// Fit the data points using linear regression analysis
const regressionResult = linearRegression(fittedData, runtimes);
// Check the R-squared value of the fit. It is usually considered a valid fit if it is greater than 0.9.
if (regressionResult.rSquared >= 0.9) {
complexities.push(complexity);
}
}
// If there is no valid fitting result, return "cannot estimate", otherwise return the estimated time complexity
if (complexities.length === 0) {
return 'Unable to estimate';
} else {
return complexities.join(' or ');
}
}
const methodLogs: Map<string, [number, number][]> = new Map();
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export function logBigOMetricsWrap<F extends AnyFunction>(fn: F, args: Parameters<F>, fnName: string) {
const startTime = performance.now();
const result = fn(args);
const endTime = performance.now();
const runTime = endTime - startTime;
const methodName = `${fnName}`;
if (!methodLogs.has(methodName)) {
methodLogs.set(methodName, []);
}
const methodLog = methodLogs.get(methodName);
const maxDataSize = args.length === 1 && typeof args[0] === 'number' ? args[0] : findPotentialN(args);
if (methodLog) {
methodLog.push([runTime, maxDataSize]);
if (methodLog.length >= 20) {
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isDebug && console.log('triggered', methodName, methodLog);
const bigO = estimateBigO(
methodLog.map(([runTime]) => runTime),
methodLog.map(([runTime]) => runTime)
);
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isDebug && console.log(`Estimated Big O: ${bigO}`);
methodLogs.delete(methodName);
}
}
return result;
}
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export function logBigOMetrics(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
const originalMethod = descriptor.value;
descriptor.value = function (...args: any[]) {
const startTime = performance.now();
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const result = originalMethod.apply(this, args);
const endTime = performance.now();
const runTime = endTime - startTime;
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const methodName = `${target.constructor.name}.${propertyKey}`;
if (!methodLogs.has(methodName)) {
methodLogs.set(methodName, []);
}
const methodLog = methodLogs.get(methodName);
const maxDataSize = args.length === 1 && typeof args[0] === 'number' ? args[0] : findPotentialN(args);
if (methodLog) {
methodLog.push([runTime, maxDataSize]);
if (methodLog.length >= 20) {
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isDebug && console.log('triggered', methodName, methodLog);
const bigO = estimateBigO(
methodLog.map(([runTime]) => runTime),
methodLog.map(([runTime]) => runTime)
);
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isDebug && console.log(`Estimated Big O: ${bigO}`);
methodLogs.delete(methodName);
}
}
return result;
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};
return descriptor;
}