在Apache Crunch中是否有将PCollection转换为PTable的通用方法？

import org.apache.crunch.PCollection;
import org.apache.crunch.PTable;
import org.apache.crunch.impl.mem.MemPipeline;

public class CrunchExample {
    public static void main(String[] args) {
        PCollection<String> collection = MemPipeline.collectionOf("key1", "key2", "key1", "key3");
        
        PTable<String, Long> table = collection
                .parallelDo(new KeyValueMapper<String, Void, Pair<String, Long>>() {
                    @Override
                    public Pair<String, Long> map(String input) {
                        return Pair.of(input, 1L);
                    }
                }, tableOf(strings(), longs()))
                .groupByKey()
                .combineValues(Aggregators.SUM_LONGS());
        
        // 使用PTable进行后续操作
        // ...
    }
}