```ts
export function indexMap(labels: string[]): Record<string, number[]> {
    const result: Record<string, number[]> = {};
    for (let i = 0; i < labels.length; i++) {
        if (!result[labels[i]]) {
            result[labels[i]] = [];
        }
        result[labels[i]].push(i);
    }
    return result;
}
```