Add a new column to a Dataframe. New column i want it to be a UUID generator

问题

I want to add a new column to a Dataframe, a UUID generator.

UUID value will look something like 21534cf7-cff9-482a-a3a8-9e7244240da7

My Research:

I've tried with withColumn method in spark.

val DF2 = DF1.withColumn("newcolname", DF1("existingcolname" + 1)

So DF2 will have additional column with newcolname with 1 added to it in all rows.

By my requirement is that I want to have a new column which can generate the UUID.

回答1:

You should try something like this:

val sc: SparkContext = ...
val sqlContext = new SQLContext(sc)

import sqlContext.implicits._

val generateUUID = udf(() => UUID.randomUUID().toString)
val df1 = Seq(("id1", 1), ("id2", 4), ("id3", 5)).toDF("id", "value")
val df2 = df1.withColumn("UUID", generateUUID())

df1.show()
df2.show()

Output will be:

+---+-----+
| id|value|
+---+-----+
|id1|    1|
|id2|    4|
|id3|    5|
+---+-----+

+---+-----+--------------------+
| id|value|                UUID|
+---+-----+--------------------+
|id1|    1|f0cfd0e2-fbbe-40f...|
|id2|    4|ec8db8b9-70db-46f...|
|id3|    5|e0e91292-1d90-45a...|
+---+-----+--------------------+

回答2:

This is how we did in Java, we had a column date and wanted to add another column with month.

Dataset<Row> newData = data.withColumn("month", month((unix_timestamp(col("date"), "MM/dd/yyyy")).cast("timestamp")));

You can use similar technique to add any column.

Dataset<Row> newData1 = newData.withColumn("uuid", lit(UUID.randomUUID().toString()));

Cheers !

来源：https://stackoverflow.com/questions/37231616/add-a-new-column-to-a-dataframe-new-column-i-want-it-to-be-a-uuid-generator