在Spark中,我们通常使用DataFrame API来进行数据操作,下面是在Spark中使用collect_list的示例代码: frompyspark.sqlimportSparkSessionfrompyspark.sql.functionsimportcollect_list# 创建Spark会话spark=SparkSession.builder.appName("ArrayAggExample").getOrCreate()# 创建示例数据data=[(1,"Alice","HR"),(2,"Bob"...
9. override def getPartitions: Array[Partition] = firstParent[T].partitions 10. 11. override def compute(split: Partition, context: TaskContext) = 12. f(context, split.index, firstParent[T].iterator(split, context)) 13. } 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 这样R...
他们在函数列表中清楚地显示了array_agg（）：https://spark.apache.org/docs/latest/api/sql/index.h...
name,array_sort(t1.courses) as courses from ( select name,array_agg(courses) as courses from students group by name ) as t1 t1的数据是: name courses Charlie ["Math","Art"] Bob ["English","History","Art"] Alice ["Math","Science"] Emma ["Math","English","Science"] David ["...
jdbcDF.agg("id" -> "max", "c4" -> "sum") Union unionAll 方法:对两个DataFrame进行组合 ,类似于 SQL 中的 UNION ALL 操作。 Join 笛卡尔积 joinDF1.join(joinDF2) using一个字段形式 下面这种join类似于 a join b using column1 的形式,需要两个DataFrame中有相同的一个列名 joinDF1.join(join...
struct组合map array 结构 1.hive建表语句 droptableappopendetail;createtableifnotexistsappopendetail ( username String, appname String, opencountINT)rowformat delimited fields terminatedby'|'location'/hive/table/appopendetail';createtableifnotexistsappopentablestruct_map ...
相信 Spark 大家都知道,它是一款基于内存的并行计算框架,在业界占有举足轻重的地位,是很多大数据公司的首选。之前介绍 Hadoop 的时候说过,相比 Spark,MapReduce 是非常鸡肋的,无论是简洁度还是性能,都远远落后于 Spark。此外,Spark 还支持使用多种语言进行编程,比如 Python、R、Java、Scala 等等。而笔者本人是专攻 ...
(args: Array[String]): Unit = {//1.创建SparkSession,因为StructuredStreaming的数据模型也是DataFrame/DataSetval spark: SparkSession = SparkSession.builder().master("local[*]").appName("SparkSQL").getOrCreate()val sc: SparkContext = spark.sparkContextsc.setLogLevel("WARN")val Schema: ...
name,array_agg(courses) as courses from student group by name; 1. 2. 3. 4. 5. 6. select name, collect_list(courses) as courses from student group by name 1. 2. 3. -- chat GPT 说这样也可以,但是我选择的版本不支持。 -- STRING_AGG 函数是 SQL:2016 标准中新增的函数,不是所有的数...
select course,count(distinct name) as student_count from ( select name ,explode(courses) as course from ( select name ,array_agg(courses) as courses from student group by name ) ) as temp group by course; coursestudent_count Science 3 Art 2 Math 3 English 2 History 1 需求5 直接在数...