export function groupBy<T>(array: T[], key: keyof T): Record<string, T[]> {
return array.reduce((result, item) => {
const groupKey = String(item[key]);
if (!result[groupKey]) {
result[groupKey] = [];
}
result[groupKey].push(item);
return result;
}, {} as Record<string, T[]>);
}
export function countBy<T>(array: T[], key: keyof T): Record<string, number> {
return array.reduce((result, item) => {
const groupKey = String(item[key]);
result[groupKey] = (result[groupKey] || 0) + 1;
return result;
}, {} as Record<string, number>);
}
export function sumBy<T>(array: T[], key: keyof T): number {
return array.reduce((sum, item) => {
const value = item[key];
return sum + (typeof value === 'number' ? value : 0);
}, 0);
}
export function averageBy<T>(array: T[], key: keyof T): number {
if (array.length === 0) return 0;
return sumBy(array, key) / array.length;
}
export function maxBy<T>(array: T[], key: keyof T): T | undefined {
if (array.length === 0) return undefined;
return array.reduce((max, item) => {
const value = item[key];
const maxValue = max[key];
if (typeof value === 'number' && typeof maxValue === 'number') {
return value > maxValue ? item : max;
}
return max;
});
}
export function minBy<T>(array: T[], key: keyof T): T | undefined {
if (array.length === 0) return undefined;
return array.reduce((min, item) => {
const value = item[key];
const minValue = min[key];
if (typeof value === 'number' && typeof minValue === 'number') {
return value < minValue ? item : min;
}
return min;
});
}
export function unique<T>(array: T[]): T[] {
return [...new Set(array)];
}
export function uniqueBy<T>(array: T[], key: keyof T): T[] {
const seen = new Set();
return array.filter(item => {
const value = item[key];
if (seen.has(value)) {
return false;
}
seen.add(value);
return true;
});
}
export function sortBy<T>(array: T[], key: keyof T, order: 'asc' | 'desc' = 'asc'): T[] {
return [...array].sort((a, b) => {
const aVal = a[key];
const bVal = b[key];
if (aVal === bVal) return 0;
let comparison = 0;
if (typeof aVal === 'number' && typeof bVal === 'number') {
comparison = aVal - bVal;
} else {
comparison = String(aVal).localeCompare(String(bVal));
}
return order === 'asc' ? comparison : -comparison;
});
}
export function paginate<T>(array: T[], page: number, itemsPerPage: number): {
data: T[];
total: number;
page: number;
itemsPerPage: number;
totalPages: number;
} {
const total = array.length;
const totalPages = Math.ceil(total / itemsPerPage);
const start = (page - 1) * itemsPerPage;
const end = start + itemsPerPage;
const data = array.slice(start, end);
return {
data,
total,
page,
itemsPerPage,
totalPages
};
}
