使用scala以其他列的长度作为值添加列

我的任务是计算每个列的长度，并将消息添加到“errorMsg”列。我可以根据长度筛选记录，但不能在新列中追加消息

例如。 我只想找出新列“ErrorMsg”上有消息的无效记录

记录长度=4

InputDataFrame-             
+------+
| value|
+------+
|Pra   |
|Akshay|
|  Raju|
|Shakti|
|xyz   |
+------+

输出数据帧

+------+------------------------+
| value|ErrorMsg                |
+------+------------------------+
|Pra   |Less Than total Length
|Akshay|Greater than total length 
|Shakti|Greater than total length
|xyx   |Less than total length
+------+-------------------------

---

如果raju是我的真实记录，它将转到有效记录，而不显示消息。

以下内容将获得所需的结果

val df = Seq("Pra", "Akshay", "Raju", "Shakti", "xyz").toDF("value")
df
 .filter(not(length($"value") === 4))
 .withColumn("ErrorMsg", when(length($"value") > lit(4), "Greater than total length").otherwise("Less Than total Length"))
 .show(10000, false)

+------+-------------------------+
|value |ErrorMsg                 |
+------+-------------------------+
|Pra   |Less Than total Length   |
|Akshay|Greater than total length|
|Shakti|Greater than total length|
|xyz   |Less Than total Length   |
+------+-------------------------+