How to remove quotes from front and end of the string Scala - regex

Question

I have a dataframe where some strings contains "" in front and end of the string.
Eg:
+-------------------------------+
|data |
+-------------------------------+
|"john belushi" |
|"john mnunjnj" |
|"nmnj tyhng" |
|"John b-e_lushi" |
|"john belushi's book" |
Expected output:
+-------------------------------+
|data |
+-------------------------------+
|john belushi |
|john mnunjnj |
|nmnj tyhng |
|John b-e_lushi |
|john belushi's book |
I am trying to remove only " double quotes from the string. Can some one tell me how can I remove this in Scala ?
Python provide ltrim and rtrim. Is there any thing equivalent to that in Scala ?

Answer 1

Use expr, substring and length functions and get the substring from 2 and length() - 2
val df_d = List("\"john belushi\"", "\"John b-e_lushi\"", "\"john belushi's book\"")
.toDF("data")
Input:
+---------------------+
|data |
+---------------------+
|"john belushi" |
|"John b-e_lushi" |
|"john belushi's book"|
+---------------------+
Using expr, substring and length functions:
import org.apache.spark.sql.functions.expr
df_d.withColumn("data", expr("substring(data, 2, length(data) - 2)"))
.show(false)
Output:
+-------------------+
|data |
+-------------------+
|john belushi |
|John b-e_lushi |
|john belushi's book|
+-------------------+

Answer 2

How to remove quotes from front and end of the string Scala?
myString.substring(1, myString.length()-1) will remove the double quotes.
import spark.implicits._
val list = List("\"hi\"", "\"I am learning scala\"", "\"pls\"", "\"help\"").toDF()
list.show(false)
val finaldf = list.map {
row => {
val stringdoublequotestoberemoved = row.getAs[String]("value")
stringdoublequotestoberemoved.substring(1, stringdoublequotestoberemoved.length() - 1)
}
}
finaldf.show(false)
Result :
+--------------------+
| value|
+--------------------+
| "hi"|
|"I am learning sc...|
| "pls"|
| "help"|
+--------------------+
+-------------------+
| value|
+-------------------+
| hi|
|I am learning scala|
| pls|
| help|
+-------------------+

Answer 3

Try it
scala> val dataFrame = List("\"john belushi\"","\"john mnunjnj\"" , "\"nmnj tyhng\"" ,"\"John b-e_lushi\"", "\"john belushi's book\"").toDF("data")
scala> dataFrame.map { row => row.mkString.stripPrefix("\"").stripSuffix("\"")}.show
+-------------------+
| value|
+-------------------+
| john belushi|
| john mnunjnj|
| nmnj tyhng|
| John b-e_lushi|
|john belushi's book|
+-------------------+