将标题和列添加到数据框火花 [英] add header and column to dataframe spark
本文介绍了将标题和列添加到数据框火花的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有一个要在其上添加标题和第一列的数据框 手动在这里是数据框
hi guys i've got a dataframe on which i want to add a header and a first column manually here is the dataframe
import org.apache.spark.sql.SparkSession
val spark = SparkSession.builder.master("local").appName("my-spark-app").getOrCreate()
val df = spark.read.option("header",true).option("inferSchema",true).csv("C:\\gg.csv").cache()
数据框的内容
12,13,14
11,10,5
3,2,45
预期输出为
define,col1,col2,col3
c1,12,13,14
c2,11,10,5
c3,3,2,45
任何帮助将不胜感激.
推荐答案
以下是基于Spark 2.4的解决方案:
Here is a solution that depends on Spark 2.4:
import org.apache.spark.sql.SparkSession
import org.apache.spark.sql.types.{IntegerType, StringType, StructField, StructType}
import org.apache.spark.sql.Row
//First off the dataframe needs to be loaded with the expected schema
val spark = SparkSession.builder().appName().getOrCreate()
val schema = new StructType()
.add("col1",IntegerType,true)
.add("col2",IntegerType,true)
.add("col3",IntegerType,true)
val df = spark.read.format("csv").schema(schema).load("C:\\gg.csv").cache()
val rddWithId = df.rdd.zipWithIndex
// Prepend "define" column of type Long
val newSchema = StructType(Array(StructField("define", StringType, false)) ++ df.schema.fields)
val dfZippedWithId = spark.createDataFrame(rddWithId.map{
case (row, index) =>
Row.fromSeq(Array("c" + index) ++ row.toSeq)}, newSchema)
// Show results
dfZippedWithId.show
显示:
+------+----+----+----+
|define|col1|col2|col3|
+------+----+----+----+
| c0| 12| 13| 14|
| c1| 11| 10| 5|
| c2| 3| 2| 45|
+------+----+----+----+
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