My Code:
var data = spark.read.option("header", "true")
.option("inferSchema", "true")
.csv("src/main/resources/student.csv")
data.show()
Data looks like:
ID Name City
1 Ali swl
2 Sana lhr
3 Ahad khi
4 ABC fsd
Now I have a list of values like (1,2,1).
val nums: List[Int] = List(1, 2, 1)
And I want to add these values against ID= 3
. So that DataFrame may look like.
ID Name City newCol newCol2 newCol3
1 Ali swl null null null
2 Sana lhr null null null
3 Ahad khi 1 2 1
4 ABC fsd null null null
I wonder if it is possible? Any help will be appreciated. Thanks
Firstly you can convert it to DataFrame
with single array column and then "decompose" the array column into columns as follows:
import org.apache.spark.sql.functions.{col, lit}
import spark.implicits._
val numsDf =
Seq(nums)
.toDF("nums")
.select(nums.indices.map(i => col("nums")(i).alias(s"newCol$i")): _*)
After that you can use outer join for joining data
to numsDf
with ID == 3
condition as follows:
val resultDf = data.join(numsDf, data.col("ID") === lit(3), "outer")
resultDf.show()
will print:
+---+----+----+-------+-------+-------+
| ID|Name|City|newCol0|newCol1|newCol2|
+---+----+----+-------+-------+-------+
| 1| Ali| swl| null| null| null|
| 2|Sana| lhr| null| null| null|
| 3|Ahad| khi| 1| 2| 3|
| 4| ABC| fsd| null| null| null|
+---+----+----+-------+-------+-------+
Make sure you have added spark.sql.crossJoin.crossJoin.enabled = true
option to the spark session:
val spark = SparkSession.builder()
...
.config("spark.sql.crossJoin.enabled", value = true)
.getOrCreate()
Yes, Its possible.
Use when
for populating matched values & otherwise
for not matched values.
I have used zipWithIndex for making column names unique.
Please check below code.
scala> import org.apache.spark.sql.functions._
scala> val df = Seq((1,"Ali","swl"),(2,"Sana","lhr"),(3,"Ahad","khi"),(4,"ABC","fsd")).toDF("id","name","city") // Creating DataFrame with given sample data.
df: org.apache.spark.sql.DataFrame = [id: int, name: string ... 1 more field]
scala> val nums = List(1,2,1) // List values.
nums: List[Int] = List(1, 2, 1)
scala> val filterData = List(3,4)
scala> spark.time{ nums.zipWithIndex.foldLeft(df)((df,c) => df.withColumn(s"newCol${c._2}",when($"id".isin(filterData:_*),c._1).otherwise(null))).show(false) } // Used zipWithIndex to make column names unique.
+---+----+----+-------+-------+-------+
|id |name|city|newCol0|newCol1|newCol2|
+---+----+----+-------+-------+-------+
|1 |Ali |swl |null |null |null |
|2 |Sana|lhr |null |null |null |
|3 |Ahad|khi |1 |2 |1 |
|4 |ABC |fsd |1 |2 |1 |
+---+----+----+-------+-------+-------+
Time taken: 43 ms
scala>
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