我有一个带有游戏的数据框和三个来自不同评论的每个游戏的值，每个值都在另一个数据框中转换，如您所见：

Df_reviews
+--------+-------+-------+--------+
|Game    | rev_1 | rev_2 | rev_3  |
+- ------+-------+-------+--------+
|CA      |XX+    | K2    | L1     |
|FT      |Z-     | K1+   | L3     |

Df_rev1
+----------+-------------+ 
| review_1 | Equivalence | 
+----------+-------------+
|XX+       | 9           |      
|Y         | 6           |
|Z-        | 3           |   

Df_rev2
+----------+-------------+
| review_2 | Equivalence | 
+----------+-------------+
|K2        | 7           |      
|K1+       | 6           |
|K3        | 10          | 

Df_rev3
+----------+-------------+
| review_3 | Equivalence | 
+----------+-------------+
|L3        | 10          |      
|L2        | 9           |
|L1        | 8           |

我必须在一个新的Dataframe中使用traduced的值，并添加一个具有第二个最佳值的列，例如：

Df_output
+--------+---------+---------+----------+-------------+
|Game    | rev_1_t | rev_2_t | rev_3_t  | second_best |
+--------+---------+---------+----------+-------------+
|CA      |  9      |  7      | 8        |     8       |
|FT      |  3      |  6      | 10       |     6       |

为了减少它，我尝试用左连接，但我太迷路了。我该怎么处理？

####### 第二部分####################如何将一个Dataframe中的列转换为另一个Dataframe中的列，将多个列？例如：

Df_revuews
+--------+-------+-------+--------+
|Game    | rev_1 | rev_2 | rev_3  |
+- ------+-------+-------+--------+
|CA      |XX+    | K2    | L1     |
|FT      |Z-     | K1+   | L3     |

Df_equiv
+--------+-------+
|Valorat | num   |
+- ------+-------+
|X       |3      |
|XX+     |5      |
|Z       |7      |
|Z-      |6      |
|K1+     |6      |
|K2      |4      |
|L1      |5      |
|L2      |6      |
|L3      |7      |

Output
+--------+-------+-------+--------+
|Game    | rev_1 | rev_2 | rev_3  |
+- ------+-------+-------+--------+
|CA      |5      | 4     | 5      |
|FT      |6      | 6     | 7      |

正如你所看到的，我正在这样做：

val joined = df_reviews
.join(df_equiv, df_reviews("rev_1") === df_equiv("num") && df_reviews("rev_2") === df_equiv("num")
&& df_reviews("rev_3") === df_equiv("num"), "left")
.select(df_reviews("Game"), 
        df_equiv("num").as("rev_1_t"), 
        df_equiv("num").as("rev_2_t"), 
        df_equiv("num").as("rev_3_t")
       )

提前谢谢！