示例
数据框：A
Word_A Frequency
0 Large 10
1 Happy 15
数据框：B
Word_B Document
0 Big 1
1 Huge 1
2 Great 2
3 Cheerful 1
4 Merry 3
5 Joyful 2
结果数据框：C
（数据框A中的单词已映射到数据框B中的同义词）
Word_A Word_B Frequency Document
0 Large Big 10 1
1 Large Huge 10 1
2 Large Great 10 2
3 Happy Cheerful 15 1
4 Happy Merry 15 3
5 Happy Joyful 15 2