1)准备数据源文件。 Spark安装目录中自带了一个people.json文件,位于“examples/src/main/resources/”目录下。其内容如下: {"name":"Michael"} {"name":"Andy", "age":30} {"name":"Justin", "age":19} 我们将这个people.json文件,拷贝到/home/hduser/data/s
Notes --- This method should only be used if the resulting array is expected to be small, as all the data is loaded into the driver's memory. Examples --- >>> rdd = sc.parallelize(range(0, 10)) >>> len(rdd.takeSample(True, 20, 1)) 20 >>> len(rdd.takeSample(False, 5,...
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Examples of Wide transformations are groupBy, reduceBy, join, etc. 宽转换的示例包括groupBy,reduceBy,join等。 The groupBy is a transformation in which the values of the column are grouped to form a unique set of values. To perform this operation is costly in distributed environments because all...
在PySpark中,RDD(Resilient Distributed Dataset)是一个不可变的分布式数据集,它可以在集群中的多个节点上进行并行操作。重新排列RDD通常指的是改变其分区布局,以便...
1 Transformation 转换操作具有懒惰执行的特性,它只指定新的RDD和其父RDD的依赖关系,只有当Action操作触发到该依赖的时候,它才被计算。 2 map 操作对每个元素进行一个映射转换 3 filter 应用过滤条件过滤掉一些数据 4 flatMap 操作执行将每个元素生成一个Array后压平 ...
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PySpark Join Types Explained with Examples PySpark Union and UnionAll Explained PySpark UDF (User Defined Function) PySpark flatMap() Transformation PySpark map Transformation PySpark SQL Functions PySpark Aggregate Functions with Examples PySpark Window Functions PySpark Datasources PySpark Read CSV file int...
df_parquet = spark.read.parquet("examples/src/main/resources/users.parquet") ## orc df_orc = spark.read.orc("examples/src/main/resources/users.orc") ## rdd sc = spark.sparkContext rdd = sc.textFile('examples/src/main/resources/people.json') ...
We’ve already mentioned the strengths of PySpark, but let’s look at a few specific examples of where you can use them: Data ETL. PySpark ability for efficient data cleaning and transformation is used for processing sensor data and production logs in manufacturing and logistics. Machine learnin...