I use Spark 2.1.
I have some data in a Spark Dataframe, which looks like below:
**ID** **type** **val**
1 t1 v1
1 t11 v11
2 t2 v2
I want to pivot up this data using either spark Scala (preferably) or Spark SQL so that final output should look like below:
**ID** **t1** **t11** **t2**
1 v1 v11
2 v2
You can use groupBy.pivot:
import org.apache.spark.sql.functions.first
df.groupBy("ID").pivot("type").agg(first($"val")).na.fill("").show
+---+---+---+---+
| ID| t1|t11| t2|
+---+---+---+---+
| 1| v1|v11| |
| 2| | | v2|
+---+---+---+---+
Note: depending on the actual data, i.e. how many values there are for each combination of ID and type, you might choose a different aggregation function.
Here's one way to do it:
val df = Seq(
(1, "T1", "v1"),
(1, "T11", "v11"),
(2, "T2", "v2")
).toDF(
"id", "type", "val"
).as[(Int, String, String)]
val df2 = df.groupBy("id").pivot("type").agg(concat_ws(",", collect_list("val")))
df2.show
+---+---+---+---+
| id| T1|T11| T2|
+---+---+---+---+
| 1| v1|v11| |
| 2| | | v2|
+---+---+---+---+
Note that if there are different vals associated with a given type, they will be grouped (comma-delimited) under the type in df2.
This one should work
val seq = Seq((123,"2016-01-01","1"),(123,"2016-01-02","2"),(123,"2016-01-03","3"))
val seq = Seq((1,"t1","v1"),(1,"t11","v11"),(2,"t2","v2"))
val df = seq.toDF("id","type","val")
val pivotedDF = df.groupBy("id").pivot("type").agg(first("val"))
pivotedDF.show
Output:
+---+----+----+----+
| id| t1| t11| t2|
+---+----+----+----+
| 1| v1| v11|null|
| 2|null|null| v2|
+---+----+----+----+
Related
I have a dataframe with two multiple columns, two of which are id and label as shown below.
+---+---+---+
| id| label|
+---+---+---+
| 1| "abc"|
| 1| "abc"|
| 1| "def"|
| 2| "def"|
| 2| "def"|
+---+---+---+
I want to groupBy "id" and aggregate the label column by counts (ignore null) of label in a map data structure and the expected result is as shown below:
+---+---+--+--+--+--+--+--
| id| label |
+---+-----+----+----+----+
| 1| {"abc":2, "def":1}|
| 2| {"def":2} |
+---+-----+----+----+----+
Is it possible to do this without using user-defined aggregate functions? I saw a similar answer here, but it doesn't aggregate based on the count of each item.
I apologize if this question is silly, I am new to both Scala and Spark.
Thanks
Without Custom UDFs
import org.apache.spark.sql.functions.{map, collect_list}
df.groupBy("id", "label")
.count
.select($"id", map($"label", $"count").as("map"))
.groupBy("id")
.agg(collect_list("map"))
.show(false)
+---+------------------------+
|id |collect_list(map) |
+---+------------------------+
|1 |[[def -> 1], [abc -> 2]]|
|2 |[[def -> 2]] |
+---+------------------------+
Using Custom UDF,
import org.apache.spark.sql.functions.udf
val customUdf = udf((seq: Seq[String]) => {
seq.groupBy(x => x).map(x => x._1 -> x._2.size)
})
df.groupBy("id")
.agg(collect_list("label").as("list"))
.select($"id", customUdf($"list").as("map"))
.show(false)
+---+--------------------+
|id |map |
+---+--------------------+
|1 |[abc -> 2, def -> 1]|
|2 |[def -> 2] |
+---+--------------------+
Creating a multiple columns from array column
Dataframe
Car name | details
Toyota | [[year,2000],[price,20000]]
Audi | [[mpg,22]]
Expected dataframe
Car name | year | price | mpg
Toyota | 2000 | 20000 | null
Audi | null | null | 22
You can try this
Let's define the data
scala> val carsDF = Seq(("toyota",Array(("year", 2000), ("price", 100000))), ("Audi", Array(("mpg", 22)))).toDF("car", "details")
carsDF: org.apache.spark.sql.DataFrame = [car: string, details: array<struct<_1:string,_2:int>>]
scala> carsDF.show(false)
+------+-----------------------------+
|car |details |
+------+-----------------------------+
|toyota|[[year,2000], [price,100000]]|
|Audi |[[mpg,22]] |
+------+-----------------------------+
Splitting the data & accessing the values in the data
scala> carsDF.withColumn("split", explode($"details")).withColumn("col", $"split"("_1")).withColumn("val", $"split"("_2")).select("car", "col", "val").show
+------+-----+------+
| car| col| val|
+------+-----+------+
|toyota| year| 2000|
|toyota|price|100000|
| Audi| mpg| 22|
+------+-----+------+
Define the list of columns that are required
scala> val colNames = Seq("mpg", "price", "year", "dummy")
colNames: Seq[String] = List(mpg, price, year, dummy)
Use pivoting on the above defined column names gives required output.
By giving new column names in the sequence makes it a single point input
scala> weDF.groupBy("car").pivot("col", colNames).agg(avg($"val")).show
+------+----+--------+------+-----+
| car| mpg| price| year|dummy|
+------+----+--------+------+-----+
|toyota|null|100000.0|2000.0| null|
| Audi|22.0| null| null| null|
+------+----+--------+------+-----+
This seems more elegant & easy way to achieve the output
you can do it like that
import org.apache.spark.functions.col
val df: DataFrame = Seq(
("toyota",Array(("year", 2000), ("price", 100000))),
("toyota",Array(("year", 2001)))
).toDF("car", "details")
+------+-------------------------------+
|car |details |
+------+-------------------------------+
|toyota|[[year, 2000], [price, 100000]]|
|toyota|[[year, 2001]] |
+------+-------------------------------+
val newdf = df
.withColumn("year", when(col("details")(0)("_1") === lit("year"), col("details")(0)("_2")).otherwise(col("details")(1)("_2")))
.withColumn("price", when(col("details")(0)("_1") === lit("price"), col("details")(0)("_2")).otherwise(col("details")(1)("_2")))
.drop("details")
newdf.show()
+------+----+------+
| car|year| price|
+------+----+------+
|toyota|2000|100000|
|toyota|2001| null|
+------+----+------+
I am comparing two dataframes (basically these are schema of two different data sources one from hive and other from SAS9.2)
I need to validate structure for both data sources so I converted schema into two dataframes and here they are:
SAS schema will be in below format:
scala> metadata.show
+----+----------------+----+---+-----------+-----------+
|S_No| Variable|Type|Len| Format| Informat|
+----+----------------+----+---+-----------+-----------+
| 1| DATETIME| Num| 8|DATETIME20.|DATETIME20.|
| 2| LOAD_DATETIME| Num| 8|DATETIME20.|DATETIME20.|
| 3| SOURCE_BANK|Char| 1| null| null|
| 4| EMP_NAME|Char| 50| null| null|
| 5|HEADER_ROW_COUNT| Num| 8| null| null|
| 6| EMP_HOURS| Num| 8| 15.2| 15.1|
+----+----------------+----+---+-----------+-----------+
Similarly hive metadata will be in below format:
df2.show
+----------------+-------------+
| Variable| type|
+----------------+-------------+
| datetime|TimestampType|
| load_datetime|TimestampType|
| source_bank| StringType|
| emp_name| StringType|
|header_row_count| IntegerType|
| emp_hours| DoubleType|
+----------------+-------------+
Now, I need to compare both these on column type and validate structure.Like for "Num" type equivalent is "Integertype".
Finally I need to store anon zero value as output if schema validation is successful
How can I achieve this ?
you can join the two dataframes and then compare the two columns corressponding to the columns type via a Map and UDF.
This is a code sample that does that.
You need to complete the map with the right values
val sqlCtx = sqlContext
import sqlCtx.implicits._
val metadata: DataFrame= Seq(
(Some("1"), "DATETIME", "Num", "8", "DATETIME20", "DATETIME20"),
(Some("3"), "SOURCEBANK", "Num", "1", "null", "null")
).toDF("SNo", "Variable", "Type", "Len", "Format", "Informat")
val metadataAdapted: DataFrame = metadata
.withColumn("Name", functions.upper(col("Variable")))
.withColumnRenamed("Type", "TypeHive")
val sasDF = Seq(("datetime", "TimestampType"),
("datetime", "TimestampType")
).toDF("variable", "type")
val sasDFAdapted = sasDF
.withColumn("Name", functions.upper(col("variable")))
.withColumnRenamed("Type", "TypeSaS")
val res = sasDFAdapted.join(metadataAdapted, Seq("Name"), "inner")
val map = Map("TimestampType" -> "Num")
def udfType(dict: Map[String, String]) = functions.udf( (typeVar: String) => dict(typeVar))
val result = res.withColumn("correctMapping", udfType(map)(col("TypeSaS")) === col("TypeHive"))
I have two tables, one called Reasons that has 9 records and another containing IDs with 40k records.
IDs:
+------+------+
|pc_pid|pc_aid|
+------+------+
| 4569| 1101|
| 63961| 1101|
|140677| 4364|
|127113| 7|
| 96097| 480|
| 8309| 3129|
| 45218| 89|
|147036| 3289|
| 88493| 3669|
| 29973| 3129|
|127444| 3129|
| 36095| 89|
|131001| 1634|
|104731| 781|
| 79219| 244|
+-------------+
Reasons:
+-----------------+
| reasons|
+-----------------+
| follow up|
| skin chk|
| annual meet|
|review lab result|
| REF BY DR|
| sick visit|
| body pain|
| test|
| other|
+-----------------+
I want output like this
|pc_pid|pc_aid| reason
+------+------+-------------------
| 4569| 1101| body pain
| 63961| 1101| review lab result
|140677| 4364| body pain
|127113| 7| sick visit
| 96097| 480| test
| 8309| 3129| other
| 45218| 89| follow up
|147036| 3289| annual meet
| 88493| 3669| review lab result
| 29973| 3129| REF BY DR
|127444| 3129| skin chk
| 36095| 89| other
In the reasons I have only 9 records and in the ID dataframe I have 40k records, I want to assign reason randomly to each and every id.
The following solution tries to be more robust to the number of reasons (ie. you can have as many reasons as you can reasonably fit in your cluster). If you just have few reasons (like the OP asks), you can probably broadcast them or embed them in a udf and easily solve this problem.
The general idea is to create an index (sequential) for the reasons and then random values from 0 to N (where N is the number of reasons) on the IDs dataset and then join the two tables using these two new columns. Here is how you can do this:
case class Reasons(s: String)
defined class Reasons
case class Data(id: Long)
defined class Data
Data will hold the IDs (simplified version of the OP) and Reasons will hold some simplified reasons.
val d1 = spark.createDataFrame( Data(1) :: Data(2) :: Data(10) :: Nil)
d1: org.apache.spark.sql.DataFrame = [id: bigint]
d1.show()
+---+
| id|
+---+
| 1|
| 2|
| 10|
+---+
val d2 = spark.createDataFrame( Reasons("a") :: Reasons("b") :: Reasons("c") :: Nil)
+---+
| s|
+---+
| a|
| b|
| c|
+---+
We will later need the number of reasons so we calculate that first.
val numerOfReasons = d2.count()
val d2Indexed = spark.createDataFrame(d2.rdd.map(_.getString(0)).zipWithIndex)
d2Indexed.show()
+---+---+
| _1| _2|
+---+---+
| a| 0|
| b| 1|
| c| 2|
+---+---+
val d1WithRand = d1.select($"id", (rand * numerOfReasons).cast("int").as("rnd"))
The last step is to join on the new columns and the remove them.
val res = d1WithRand.join(d2Indexed, d1WithRand("rnd") === d2Indexed("_2")).drop("_2").drop("rnd")
res.show()
+---+---+
| id| _1|
+---+---+
| 2| a|
| 10| b|
| 1| c|
+---+---+
pyspark random join itself
data_neg = data_pos.sortBy(lambda x: uniform(1, 10000))
data_neg = data_neg.coalesce(1, False).zip(data_pos.coalesce(1, True))
The fastest way to randomly join dataA (huge dataframe) and dataB (smaller dataframe, sorted by any column):
dfB = dataB.withColumn(
"index", F.row_number().over(Window.orderBy("col")) - 1
)
dfA = dataA.withColumn("index", (F.rand() * dfB.count()).cast("bigint"))
df = dfA.join(dfB, on="index", how="left").drop("index")
Since dataB is already sorted, row numbers can be assigned over sorted window with high degree of parallelism. F.rand() is another highly parallel function, so adding index to dataA will be very fast as well.
If dataB is small enough, you may benefit from broadcasting it.
This method is better than using:
zipWithIndex: Can be very expensive to convert dataframe to rdd, zipWithIndex, and then to df.
monotonically_increasing_id: Need to be used with row_number which will collect all the partitions into a single executor.
Reference: https://towardsdatascience.com/adding-sequential-ids-to-a-spark-dataframe-fa0df5566ff6
I am using scala and spark and have a simple dataframe.map to produce the required transformation on data. However I need to provide an additional row of data with the modified original. How can I use the dataframe.map to give out this.
ex:
dataset from:
id, name, age
1, john, 23
2, peter, 32
if age < 25 default to 25.
dataset to:
id, name, age
1, john, 25
1, john, -23
2, peter, 32
Would a 'UnionAll' handle it?
eg.
df1 = original dataframe
df2 = transformed df1
df1.unionAll(df2)
EDIT: implementation using unionAll()
val df1=sqlContext.createDataFrame(Seq( (1,"john",23) , (2,"peter",32) )).
toDF( "id","name","age")
def udfTransform= udf[Int,Int] { (age) => if (age<25) 25 else age }
val df2=df1.withColumn("age2", udfTransform($"age")).
where("age!=age2").
drop("age2")
df1.withColumn("age", udfTransform($"age")).
unionAll(df2).
orderBy("id").
show()
+---+-----+---+
| id| name|age|
+---+-----+---+
| 1| john| 25|
| 1| john| 23|
| 2|peter| 32|
+---+-----+---+
Note: the implementation differs a bit from the originally proposed (naive) solution. The devil is always in the detail!
EDIT 2: implementation using nested array and explode
val df1=sx.createDataFrame(Seq( (1,"john",23) , (2,"peter",32) )).
toDF( "id","name","age")
def udfArr= udf[Array[Int],Int] { (age) =>
if (age<25) Array(age,25) else Array(age) }
val df2=df1.withColumn("age", udfArr($"age"))
df2.show()
+---+-----+--------+
| id| name| age|
+---+-----+--------+
| 1| john|[23, 25]|
| 2|peter| [32]|
+---+-----+--------+
df2.withColumn("age",explode($"age") ).show()
+---+-----+---+
| id| name|age|
+---+-----+---+
| 1| john| 23|
| 1| john| 25|
| 2|peter| 32|
+---+-----+---+