如果还没有DataFrame,可以从数据源(如CSV文件)加载数据创建一个新的DataFrame。以下是一个加载CSV文件的例子: scala val spark = SparkSession.builder() .appName("Add Column Example") .master("local[*]") .getOrCreate() val df = spark.read.option("header", "true").csv("path/to/your/file.csv...
首先,我们需要创建一个Spark DataFrame对象,以便我们可以在其中添加新的列。我们可以从文件、数据库或其他数据源中加载数据来创建DataFrame。 // 创建SparkSession对象valspark=SparkSession.builder().appName("Add Column to DataFrame").getOrCreate()// 从文件加载数据创建DataFramevaldf=spark.read.format("csv")...
}) val schema = new StructType().add("name", "string") .add("age", "string") .add("id", "long") spark.createDataFrame(record, schema).show() 1. 2. 3. 4. 5. 6. 7. 8. 结果: +---+---+---+ |name|age| id| +---+---+---+ |张三| 23| 0| |王五| 25| 1| |...
importorg.apache.spark.sql.DataFrame; importorg.apache.spark.sql.SaveMode; importorg.apache.spark.sql.hive.HiveContext; publicclassAddColumnDataFrame{ public static voidmain(String[]args){ args=newString[]{"input path"}; SparkConfconf=newSparkConf().setMaster("local").setAppName("test"); ...
三、dataframe上的关键常用操作 nyDF.show //default it will be show 20 rows .But you can specificate row number.eg nyDF.show(40) //show函数可以指定行数。 nyDF.select("Room_ID","Room_Type","Price").show //you can also specificate a row to select a special column. ...
We can add rows or columns We can remove rows or columns We can transform a row into a column (or vice versa) We can change the order of rows based on the values in columns |2.1 select and selectExpr select and selectExpr allow you to do the DataFrame equivalent of SQL queries on a...
下面的例子会先新建一个dataframe，然后将list转为dataframe，然后将两者join起来。from
idCol: org.apache.spark.sql.Column=id scala> val idCol = column("id") idCol: org.apache.spark.sql.Column= id scala> val dataset = spark.range(5).toDF("text") dataset: org.apache.spark.sql.DataFrame=[text: bigint] scala> val textCol = dataset.col("text") ...
// Add the index column for Spark DataFrame def addIndexColumn(spark: SparkSession, df: DataFrame, indexColName: String, method: String): DataFrame = { logger.info("Add the indexColName(%s) to Spark DataFrame(%s)".format(indexColName, df.toString())) method.toLowerCase() match { case...
最后,我们可以使用show()方法查看增加列后的DataFrame: newDf.show() 1. 完整的代码如下所示: importorg.apache.spark.sql.SparkSessionimportorg.apache.spark.sql.functions._valspark=SparkSession.builder().appName("Add Column").master("local").getOrCreate()valdf=spark.read.csv("employees.csv")val...