This is how I do do for 2 specific columns:
dataSet.withColumn("colName", concat(dataSet.col("col1"), lit(","),dataSet.col("col2") ));
but dataSet.columns() retruns Sting array, and not Column array.
How should I craete a List<Column>?
Thanks!
Simple Way - Instead of df.columns use concat_ws(",","*"), Check below code.
df.withColumn("colName",expr("concat_ws(',',*)")).show(false)
+---+--------+---+-------------+
|id |name |age|colName |
+---+--------+---+-------------+
|1 |Srinivas|29 |1,Srinivas,29|
|2 |Ravi |30 |2,Ravi,30 |
+---+--------+---+-------------+
Java has more verbose syntax. Try this -
df.withColumn("colName",concat_ws(",", toScalaSeq(Arrays.stream(df.columns()).map(functions::col).collect(Collectors.toList()))));
Use below utility to convert java list to scala seq-
<T> Buffer<T> toScalaSeq(List<T> list) {
return JavaConversions.asScalaBuffer(list);
}
If someone is looking for a way to concat all the columns of a DataFrame in Scala, this is what worked for me:
val df_new = df.withColumn(new_column_name, concat_ws("-", df.columns.map(col): _*))
