如果这是 SQL,我会使用INSERT INTO OUTPUT SELECT ... FROM INPUT,但我不知道如何使用 Spark SQL 来做到这一点。 具体而言: var input = sqlContext.createDataFrame(Seq( (10L, "Joe Doe", 34), (11L, "Jane Doe", 31), (12L, "Alice Jones", 25) )).toDF("id", "name", "age") var out...
Spark RDD 可以使用 Scala 和 Pyspark 语言以多种方式创建,例如,可以使用 sparkContext.parallelize() 从文本文件、另一个 RDD、DataFrame 和 Dataset 创建。 尽管我们在这里介绍了 Scala 中的大部分示例,但同…
.toDF()// Register the DataFrame as a temporary viewpeopleDF.createOrReplaceTempView("people")// SQL statements can be run by using the sql methods provided by Sparkval teenagersDF = spark.sql("SELECT name, age FROM people WHERE age BETWEEN 13 AND 19")// The columns of a row in the ...
empty: print("Empty DataFrame") else print("Non Empty DataFrame") 6. Create Empty DataFrame From Another DataFrameYou can also create a zero record DataFrame from another existing DF. This would be done to create a blank DataFrame with the same columns as the existing but without rows.# ...
* Create a Scala Spark SQL Context. */ val sqlContext = new org.apache.spark.sql.SQLContext(sc) def main(args: Array[String]) { /** * Create the DataFrame */ val df = sqlContext.read.json("src/main/resources/cars.json")
spark数据源多少种 spark数据源包括,Spark支持通过DataFrame来操作大量的数据源,包括外部文件(如json、avro、parquet、sequencefile等等)、hive、关系数据库、cassandra等等。本文测试环境为Spark1.3。加载和保存文件最简单的方式是调用load方法加载文件,默认的格式为p
把得到的schema应用于包含Row对象的RDD,调用这个方法来实现这一步:SQLContext.createDataFrame For example: 例如: // sc 是已有的SparkContext对象 val sqlContext = new org.apache.spark.sql.SQLContext(sc) // 创建一个RDD val people = sc.textFile("examples/src/main/resources/people.txt") // 数据的...
val teenagers = sqlContext.sql("SELECT name FROM people WHERE age >= 13 AND age <= 19")// 另一种方法是,用一个包含JSON字符串的RDD来创建DataFrameval anotherPeopleRDD = sc.parallelize("""{"name":"Yin","address":{"city":"Columbus","state":"Ohio"}}""":: Nil)...
10. Create From Another DataFrame Finally, you can also copy a DataFrame from another DataFrame usingcopy()method. # Copy DataFrame to another df2=df.copy() print(df2) Conclusion In this article, you have learned different ways to create a pandas DataFrame with examples. It can be created ...
Learn how to load and transform data using the Apache Spark Python (PySpark) DataFrame API, the Apache Spark Scala DataFrame API, and the SparkR SparkDataFrame API in Databricks.