add kmeans, moving-average, temporal functions, retail functions

add 
1. "ml/kmeans" (kmeans.ts) 
2. "series/moving-average" (time-helper.ts)
3. "time/week-number", "time/same-day-last-year" (time-helper.ts)
4. 購買率"retail/purchase-rate", リフト値"retail/lift-value", 原価率"retail/cost-ratio" 値入り率"retail/gross-margin" (server.ts)
This commit is contained in:
raymond 2025-09-02 04:32:29 +00:00
parent 9d2b0dc043
commit 93d192a995
3 changed files with 524 additions and 384 deletions

118
kmeans.ts Normal file
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// kmeans.ts - K-Means clustering algorithm
export interface Point {
x: number;
y: number;
}
export interface Cluster {
centroid: Point;
points: Point[];
}
export interface KMeansResult {
clusters: Cluster[];
iterations: number;
converged: boolean;
}
export class KMeans {
private readonly k: number;
private readonly maxIterations: number;
private readonly data: Point[];
private clusters: Cluster[] = [];
constructor(data: Point[], k: number, maxIterations: number = 50) {
this.k = k;
this.maxIterations = maxIterations;
this.data = data;
}
private static euclideanDistance(p1: Point, p2: Point): number {
const dx = p2.x - p1.x;
const dy = p2.y - p1.y;
return Math.sqrt(dx * dx + dy * dy);
}
private initializeCentroids(): void {
const centroids: Point[] = [];
const dataCopy = [...this.data];
for (let i = 0; i < this.k && dataCopy.length > 0; i++) {
const randomIndex = Math.floor(Math.random() * dataCopy.length);
const centroid = { ...dataCopy[randomIndex] };
centroids.push(centroid);
dataCopy.splice(randomIndex, 1);
}
this.clusters = centroids.map(c => ({ centroid: c, points: [] }));
}
private assignClusters(pointAssignments: number[]): boolean {
let hasChanged = false;
for (const cluster of this.clusters) {
cluster.points = [];
}
this.data.forEach((point, pointIndex) => {
let minDistance = Infinity;
let closestClusterIndex = -1;
this.clusters.forEach((cluster, clusterIndex) => {
const distance = KMeans.euclideanDistance(point, cluster.centroid);
if (distance < minDistance) {
minDistance = distance;
closestClusterIndex = clusterIndex;
}
});
if (pointAssignments[pointIndex] !== closestClusterIndex) {
hasChanged = true;
pointAssignments[pointIndex] = closestClusterIndex;
}
if (closestClusterIndex !== -1) {
this.clusters[closestClusterIndex].points.push(point);
}
});
return hasChanged;
}
private updateCentroids(): void {
for (const cluster of this.clusters) {
if (cluster.points.length === 0) continue;
const sumX = cluster.points.reduce((sum, p) => sum + p.x, 0);
const sumY = cluster.points.reduce((sum, p) => sum + p.y, 0);
cluster.centroid.x = sumX / cluster.points.length;
cluster.centroid.y = sumY / cluster.points.length;
}
}
public run(): KMeansResult {
this.initializeCentroids();
const pointAssignments = new Array(this.data.length).fill(-1);
let iterations = 0;
let converged = false;
for (let i = 0; i < this.maxIterations; i++) {
iterations = i + 1;
const hasChanged = this.assignClusters(pointAssignments);
this.updateCentroids();
if (!hasChanged) {
converged = true;
break;
}
}
return {
clusters: this.clusters,
iterations,
converged
};
}
}

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server.ts
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// package.json dependencies needed:
// npm install express mathjs lodash
// npm install -D @types/express @types/node @types/lodash typescript ts-node
import express from 'express';
import * as math from 'mathjs';
import * as _ from 'lodash';
const app = express();
app.use(express.json());
// Types for our data structures
interface DataSeries {
values: number[];
labels?: string[];
}
interface Condition {
field: string;
operator: '>' | '<' | '=' | '>=' | '<=' | '!=';
value: number | string;
}
interface ApiResponse<T> {
success: boolean;
data?: T;
error?: string;
}
// Helper function for error handling
const handleError = (error: unknown): string => {
return error instanceof Error ? error.message : 'Unknown error';
};
// Core statistical functions
class AnalyticsEngine {
// Apply conditions to filter data
private applyConditions(series: DataSeries, conditions: Condition[] = []): number[] {
if (conditions.length === 0) return series.values;
// For now, just return all values - you'd implement condition logic here
// This would involve checking conditions against associated metadata
return series.values;
}
// Remove duplicates from series
unique(series: DataSeries): number[] {
return _.uniq(series.values);
}
// Calculate mean with optional conditions
mean(series: DataSeries, conditions: Condition[] = []): number {
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Number(math.mean(filteredValues));
}
// Count values with optional conditions
count(series: DataSeries, conditions: Condition[] = []): number {
const filteredValues = this.applyConditions(series, conditions);
return filteredValues.length;
}
// Calculate variance
variance(series: DataSeries, conditions: Condition[] = []): number {
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Number(math.variance(filteredValues));
}
// Calculate standard deviation
standardDeviation(series: DataSeries, conditions: Condition[] = []): number {
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Number(math.std(filteredValues));
}
// Calculate percentile/quantile
percentile(
series: DataSeries,
percent: number,
ascending: boolean = true,
conditions: Condition[] = []
): number {
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
const sorted = ascending ?
_.sortBy(filteredValues) :
_.sortBy(filteredValues).reverse();
const index = (percent / 100) * (sorted.length - 1);
const lower = Math.floor(index);
const upper = Math.ceil(index);
const weight = index % 1;
return sorted[lower] * (1 - weight) + sorted[upper] * weight;
}
// Calculate median (50th percentile)
median(series: DataSeries, conditions: Condition[] = []): number {
return this.percentile(series, 50, true, conditions);
}
// Calculate mode (most frequent value)
mode(series: DataSeries, conditions: Condition[] = []): number[] {
const filteredValues = this.applyConditions(series, conditions);
const frequency = _.countBy(filteredValues);
const maxFreq = Math.max(...Object.values(frequency));
return Object.keys(frequency)
.filter(key => frequency[key] === maxFreq)
.map(Number);
}
// Rank values and get top N
topN(
series: DataSeries,
n: number,
ascending: boolean = false,
conditions: Condition[] = []
): number[] {
const filteredValues = this.applyConditions(series, conditions);
const sorted = ascending ?
_.sortBy(filteredValues) :
_.sortBy(filteredValues).reverse();
return sorted.slice(0, n);
}
// Get maximum value
max(series: DataSeries, conditions: Condition[] = []): number {
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Math.max(...filteredValues);
}
// Get minimum value
min(series: DataSeries, conditions: Condition[] = []): number {
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Math.min(...filteredValues);
}
// Calculate percent change
percentChange(series: DataSeries, step: number = 1): number[] {
const values = series.values;
const changes: number[] = [];
for (let i = step; i < values.length; i++) {
const change = ((values[i] - values[i - step]) / values[i - step]) * 100;
changes.push(change);
}
return changes;
}
// Basic correlation between two series
correlation(series1: DataSeries, series2: DataSeries): number {
if (series1.values.length !== series2.values.length) {
throw new Error('Series must have same length for correlation');
}
const x = series1.values;
const y = series2.values;
const n = x.length;
const sumX = _.sum(x);
const sumY = _.sum(y);
const sumXY = _.sum(x.map((xi, i) => xi * y[i]));
const sumX2 = _.sum(x.map(xi => xi * xi));
const sumY2 = _.sum(y.map(yi => yi * yi));
const numerator = n * sumXY - sumX * sumY;
const denominator = Math.sqrt((n * sumX2 - sumX * sumX) * (n * sumY2 - sumY * sumY));
return numerator / denominator;
}
}
// Initialize analytics engine
const analytics = new AnalyticsEngine();
// API Routes
app.get('/api/health', (req, res) => {
res.json({ status: 'OK', timestamp: new Date().toISOString() });
});
// Unique values endpoint
app.post('/api/unique', (req, res) => {
try {
const { series }: { series: DataSeries } = req.body;
const result = analytics.unique(series);
res.json({ success: true, data: result } as ApiResponse<number[]>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number[]>);
}
});
// Mean calculation endpoint
app.post('/api/mean', (req, res) => {
try {
const { series, conditions = [] }: { series: DataSeries; conditions?: Condition[] } = req.body;
const result = analytics.mean(series, conditions);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
// Count endpoint
app.post('/api/count', (req, res) => {
try {
const { series, conditions = [] }: { series: DataSeries; conditions?: Condition[] } = req.body;
const result = analytics.count(series, conditions);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
// Variance endpoint
app.post('/api/variance', (req, res) => {
try {
const { series, conditions = [] }: { series: DataSeries; conditions?: Condition[] } = req.body;
const result = analytics.variance(series, conditions);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
// Standard deviation endpoint
app.post('/api/std', (req, res) => {
try {
const { series, conditions = [] }: { series: DataSeries; conditions?: Condition[] } = req.body;
const result = analytics.standardDeviation(series, conditions);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
// Percentile endpoint
app.post('/api/percentile', (req, res) => {
try {
const {
series,
percent,
ascending = true,
conditions = []
}: {
series: DataSeries;
percent: number;
ascending?: boolean;
conditions?: Condition[]
} = req.body;
const result = analytics.percentile(series, percent, ascending, conditions);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
// Median endpoint
app.post('/api/median', (req, res) => {
try {
const { series, conditions = [] }: { series: DataSeries; conditions?: Condition[] } = req.body;
const result = analytics.median(series, conditions);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
// Mode endpoint
app.post('/api/mode', (req, res) => {
try {
const { series, conditions = [] }: { series: DataSeries; conditions?: Condition[] } = req.body;
const result = analytics.mode(series, conditions);
res.json({ success: true, data: result } as ApiResponse<number[]>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number[]>);
}
});
// Top N endpoint
app.post('/api/topn', (req, res) => {
try {
const {
series,
n,
ascending = false,
conditions = []
}: {
series: DataSeries;
n: number;
ascending?: boolean;
conditions?: Condition[]
} = req.body;
const result = analytics.topN(series, n, ascending, conditions);
res.json({ success: true, data: result } as ApiResponse<number[]>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number[]>);
}
});
// Max/Min endpoints
app.post('/api/max', (req, res) => {
try {
const { series, conditions = [] }: { series: DataSeries; conditions?: Condition[] } = req.body;
const result = analytics.max(series, conditions);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
app.post('/api/min', (req, res) => {
try {
const { series, conditions = [] }: { series: DataSeries; conditions?: Condition[] } = req.body;
const result = analytics.min(series, conditions);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
// Percent change endpoint
app.post('/api/percent-change', (req, res) => {
try {
const { series, step = 1 }: { series: DataSeries; step?: number } = req.body;
const result = analytics.percentChange(series, step);
res.json({ success: true, data: result } as ApiResponse<number[]>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number[]>);
}
});
// Correlation endpoint
app.post('/api/correlation', (req, res) => {
try {
const { series1, series2 }: { series1: DataSeries; series2: DataSeries } = req.body;
const result = analytics.correlation(series1, series2);
res.json({ success: true, data: result } as ApiResponse<number>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<number>);
}
});
// Error handling middleware
app.use((err: Error, req: express.Request, res: express.Response, next: express.NextFunction) => {
console.error(err.stack);
res.status(500).json({ success: false, error: 'Internal server error' } as ApiResponse<any>);
});
// Start server
const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
console.log(`Analytics API server running on port ${PORT}`);
console.log(`Health check: http://localhost:${PORT}/api/health`);
});
// server.ts - Simplified main server file
// package.json dependencies needed:
// npm install express mathjs lodash date-fns
// npm install -D @types/express @types/node @types/lodash typescript ts-node
import express from 'express';
import * as math from 'mathjs';
import * as _ from 'lodash';
import { KMeans, Point } from './kmeans';
import { getWeekNumber, getSameWeekDayLastYear } from './time-helper';
const app = express();
app.use(express.json());
// ========================================
// TYPE DEFINITIONS
// ========================================
interface DataSeries {
values: number[];
labels?: string[];
}
interface DataMatrix {
data: number[][];
columns?: string[];
rows?: string[];
}
interface Condition {
field: string;
operator: '>' | '<' | '=' | '>=' | '<=' | '!=';
value: number | string;
}
interface ApiResponse<T> {
success: boolean;
data?: T;
error?: string;
}
// ========================================
// HELPER FUNCTIONS
// ========================================
const handleError = (error: unknown): string => {
return error instanceof Error ? error.message : 'Unknown error';
};
const validateSeries = (series: DataSeries): void => {
if (!series || !Array.isArray(series.values) || series.values.length === 0) {
throw new Error('Series must contain at least one value');
}
};
const validateMatrix = (matrix: DataMatrix): void => {
if (!matrix || !Array.isArray(matrix.data) || matrix.data.length === 0) {
throw new Error('Matrix must contain at least one row');
}
};
/**
* A helper class to provide a fluent API for rolling window calculations.
*/
class RollingWindow {
private windows: number[][];
constructor(windows: number[][]) {
this.windows = windows;
}
mean(): number[] {
return this.windows.map(window => Number(math.mean(window)));
}
sum(): number[] {
return this.windows.map(window => _.sum(window));
}
min(): number[] {
return this.windows.map(window => Math.min(...window));
}
max(): number[] {
return this.windows.map(window => Math.max(...window));
}
toArray(): number[][] {
return this.windows;
}
}
// ========================================
// ANALYTICS ENGINE (Simplified)
// ========================================
class AnalyticsEngine {
private applyConditions(series: DataSeries, conditions: Condition[] = []): number[] {
if (conditions.length === 0) return series.values;
return series.values; // TODO: Implement filtering
}
// Basic statistical functions
unique(series: DataSeries): number[] {
validateSeries(series);
return _.uniq(series.values);
}
mean(series: DataSeries, conditions: Condition[] = []): number {
validateSeries(series);
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Number(math.mean(filteredValues));
}
count(series: DataSeries, conditions: Condition[] = []): number {
validateSeries(series);
return this.applyConditions(series, conditions).length;
}
variance(series: DataSeries, conditions: Condition[] = []): number {
validateSeries(series);
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Number(math.variance(filteredValues));
}
standardDeviation(series: DataSeries, conditions: Condition[] = []): number {
validateSeries(series);
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Number(math.std(filteredValues));
}
percentile(series: DataSeries, percent: number, ascending: boolean = true, conditions: Condition[] = []): number {
validateSeries(series);
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
const sorted = ascending ? _.sortBy(filteredValues) : _.sortBy(filteredValues).reverse();
const index = (percent / 100) * (sorted.length - 1);
const lower = Math.floor(index);
const upper = Math.ceil(index);
const weight = index % 1;
return sorted[lower] * (1 - weight) + sorted[upper] * weight;
}
median(series: DataSeries, conditions: Condition[] = []): number {
return this.percentile(series, 50, true, conditions);
}
mode(series: DataSeries, conditions: Condition[] = []): number[] {
validateSeries(series);
const filteredValues = this.applyConditions(series, conditions);
const frequency = _.countBy(filteredValues);
const maxFreq = Math.max(...Object.values(frequency));
return Object.keys(frequency)
.filter(key => frequency[key] === maxFreq)
.map(Number);
}
max(series: DataSeries, conditions: Condition[] = []): number {
validateSeries(series);
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Math.max(...filteredValues);
}
min(series: DataSeries, conditions: Condition[] = []): number {
validateSeries(series);
const filteredValues = this.applyConditions(series, conditions);
if (filteredValues.length === 0) throw new Error('No data points match conditions');
return Math.min(...filteredValues);
}
correlation(series1: DataSeries, series2: DataSeries): number {
validateSeries(series1);
validateSeries(series2);
if (series1.values.length !== series2.values.length) {
throw new Error('Series must have same length for correlation');
}
const x = series1.values;
const y = series2.values;
const n = x.length;
const sumX = _.sum(x);
const sumY = _.sum(y);
const sumXY = _.sum(x.map((xi, i) => xi * y[i]));
const sumX2 = _.sum(x.map(xi => xi * xi));
const sumY2 = _.sum(y.map(yi => yi * yi));
const numerator = n * sumXY - sumX * sumY;
const denominator = Math.sqrt((n * sumX2 - sumX * sumX) * (n * sumY2 - sumY * sumY));
return numerator / denominator;
}
// Rolling window functions
rolling(series: DataSeries, windowSize: number): RollingWindow {
validateSeries(series);
if (windowSize <= 0) {
throw new Error('Window size must be a positive number.');
}
if (series.values.length < windowSize) {
return new RollingWindow([]);
}
const windows: number[][] = [];
for (let i = 0; i <= series.values.length - windowSize; i++) {
const window = series.values.slice(i, i + windowSize);
windows.push(window);
}
return new RollingWindow(windows);
}
movingAverage(series: DataSeries, windowSize: number): number[] {
return this.rolling(series, windowSize).mean();
}
// K-means wrapper (uses imported KMeans class)
kmeans(matrix: DataMatrix, nClusters: number): { clusters: number[][][], centroids: number[][] } {
validateMatrix(matrix);
if (matrix.data[0].length !== 2) {
throw new Error('K-means implementation currently only supports 2D data.');
}
const points = matrix.data.map(row => ({ x: row[0], y: row[1] }));
const kmeans = new KMeans(points, nClusters);
const result = kmeans.run();
const centroids = result.clusters.map(c => [c.centroid.x, c.centroid.y]);
const clusters = result.clusters.map(c => c.points.map(p => [p.x, p.y]));
return { clusters, centroids };
}
// Time helper wrapper functions
getWeekNumber(dateString: string): number {
return getWeekNumber(dateString);
}
getSameWeekDayLastYear(dateString: string): string {
return getSameWeekDayLastYear(dateString);
}
// Retail functions
purchaseRate(productPurchases: number, totalTransactions: number): number {
if (totalTransactions === 0) throw new Error('Total transactions cannot be zero');
return (productPurchases / totalTransactions) * 100;
}
liftValue(jointPurchaseRate: number, productAPurchaseRate: number, productBPurchaseRate: number): number {
const expectedJointRate = productAPurchaseRate * productBPurchaseRate;
if (expectedJointRate === 0) throw new Error('Expected joint rate cannot be zero');
return jointPurchaseRate / expectedJointRate;
}
costRatio(cost: number, salePrice: number): number {
if (salePrice === 0) throw new Error('Sale price cannot be zero');
return cost / salePrice;
}
grossMarginRate(salePrice: number, cost: number): number {
if (salePrice === 0) throw new Error('Sale price cannot be zero');
return (salePrice - cost) / salePrice;
}
}
// Initialize analytics engine
const analytics = new AnalyticsEngine();
// ========================================
// ROUTE HELPER FUNCTION
// ========================================
const createRoute = <T>(
app: express.Application,
method: 'get' | 'post' | 'put' | 'delete',
path: string,
handler: (req: express.Request) => T
) => {
app[method](path, (req, res) => {
try {
const result = handler(req);
res.status(200).json({ success: true, data: result } as ApiResponse<T>);
} catch (error) {
const errorMessage = handleError(error);
res.status(400).json({ success: false, error: errorMessage } as ApiResponse<T>);
}
});
};
// ========================================
// API ROUTES
// ========================================
app.get('/api/health', (req, res) => {
res.status(200).json({ status: 'OK', timestamp: new Date().toISOString() });
});
// Statistical function routes
createRoute(app, 'post', '/api/unique', (req) => analytics.unique(req.body.series));
createRoute(app, 'post', '/api/mean', (req) => analytics.mean(req.body.series, req.body.conditions));
createRoute(app, 'post', '/api/count', (req) => analytics.count(req.body.series, req.body.conditions));
createRoute(app, 'post', '/api/variance', (req) => analytics.variance(req.body.series, req.body.conditions));
createRoute(app, 'post', '/api/std', (req) => analytics.standardDeviation(req.body.series, req.body.conditions));
createRoute(app, 'post', '/api/percentile', (req) => analytics.percentile(req.body.series, req.body.percent, req.body.ascending, req.body.conditions));
createRoute(app, 'post', '/api/median', (req) => analytics.median(req.body.series, req.body.conditions));
createRoute(app, 'post', '/api/mode', (req) => analytics.mode(req.body.series, req.body.conditions));
createRoute(app, 'post', '/api/max', (req) => analytics.max(req.body.series, req.body.conditions));
createRoute(app, 'post', '/api/min', (req) => analytics.min(req.body.series, req.body.conditions));
createRoute(app, 'post', '/api/correlation', (req) => analytics.correlation(req.body.series1, req.body.series2));
// Time series routes
createRoute(app, 'post', '/api/series/moving-average', (req) => {
const { series, windowSize } = req.body;
return analytics.movingAverage(series, windowSize);
});
createRoute(app, 'post', '/api/series/rolling', (req) => {
const { series, windowSize } = req.body;
return analytics.rolling(series, windowSize).toArray();
});
// Machine learning routes
createRoute(app, 'post', '/api/ml/kmeans', (req) => analytics.kmeans(req.body.matrix, req.body.nClusters));
// Time helper routes
createRoute(app, 'post', '/api/time/week-number', (req) => {
const { date } = req.body;
return analytics.getWeekNumber(date);
});
createRoute(app, 'post', '/api/time/same-day-last-year', (req) => {
const { date } = req.body;
return analytics.getSameWeekDayLastYear(date);
});
// Retail analytics routes
createRoute(app, 'post', '/api/retail/purchase-rate', (req) => analytics.purchaseRate(req.body.productPurchases, req.body.totalTransactions));
createRoute(app, 'post', '/api/retail/lift-value', (req) => analytics.liftValue(req.body.jointPurchaseRate, req.body.productAPurchaseRate, req.body.productBPurchaseRate));
createRoute(app, 'post', '/api/retail/cost-ratio', (req) => analytics.costRatio(req.body.cost, req.body.salePrice));
createRoute(app, 'post', '/api/retail/gross-margin', (req) => analytics.grossMarginRate(req.body.salePrice, req.body.cost));
// ========================================
// ERROR HANDLING
// ========================================
app.use((err: Error, req: express.Request, res: express.Response, next: express.NextFunction) => {
console.error(err.stack);
res.status(500).json({ success: false, error: 'Internal server error' } as ApiResponse<any>);
});
// app.use('*', (req, res) => {
// res.status(404).json({ success: false, error: 'Endpoint not found' } as ApiResponse<any>);
// });
app.use('*', (req, res) => {
res.status(404).json({ success: false, error: 'Endpoint not found' });
});
// ========================================
// SERVER STARTUP
// ========================================
const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
console.log(`Analytics API server running on port ${PORT}`);
console.log(`Health check: http://localhost:${PORT}/api/health`);
console.log('\n=== Available Endpoints ===');
console.log('GET /api/health');
console.log('POST /api/mean');
console.log('POST /api/variance');
console.log('POST /api/ml/kmeans <-- uses external kmeans.ts');
console.log('POST /api/time/week-number <-- uses external time-helper.ts');
console.log('POST /api/time/same-day-last-year');
console.log('POST /api/series/moving-average');
console.log('... and more');
});
export default app;

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time-helper.ts Normal file
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// time-helpers.ts - Date and time utility functions
import { getISOWeek, getISODay, subYears, setISOWeek, setISODay, isValid } from 'date-fns';
export const getWeekNumber = (dateString: string): number => {
const date = new Date(dateString);
if (!isValid(date)) {
throw new Error('Invalid date string provided.');
}
return getISOWeek(date);
};
export const getSameWeekDayLastYear = (dateString: string): string => {
const baseDate = new Date(dateString);
if (!isValid(baseDate)) {
throw new Error('Invalid date string provided.');
}
const originalWeek = getISOWeek(baseDate);
const originalDayOfWeek = getISODay(baseDate);
const lastYearDate = subYears(baseDate, 1);
const dateWithWeekSet = setISOWeek(lastYearDate, originalWeek);
const finalDate = setISODay(dateWithWeekSet, originalDayOfWeek);
return finalDate.toISOString().split('T')[0]; // Return as YYYY-MM-DD
};