引发选择并添加具有别名的列 [英] spark select and add columns with alias

问题描述

我想选择几列，添加几列或除以某些列，并用空格填充这些列，并以新名称存储它们作为别名.例如，SQL中的内容应类似于:

I want to select few columns, add few columns or divide, with some columns as space padded and store them with new names as alias. For example in SQL should be something like:

select "   " as col1, b as b1, c+d as e from table 

如何在Spark中实现这一目标?

How can I achieve this in Spark?

推荐答案

您还可以使用本机DF函数.例如:

You can also use the native DF functions as well. For example given:

import org.apache.spark.sql.functions._
val df1 = Seq(
 ("A",1,5,3),
 ("B",3,4,2),
 ("C",4,6,3),
 ("D",5,9,1)).toDF("a","b","c","d")

将列选择为:

df1.select(lit(" ").as("col1"),
           col("b").as("b1"),
           (col("c") + col("d")).as("e"))

为您提供了预期的结果:

gives you the expected result:

+----+---+---+
|col1| b1|  e|
+----+---+---+
|    |  1|  8|
|    |  3|  6|
|    |  4|  9|
|    |  5| 10|
+----+---+---+

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