scala 如何使用字符串数组在火花数据框中将列名设置为 toDF() 函数？
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How to set column names to toDF() function in spark dataframe using a string array?
提问by Devi
For example,
例如，
val columns=Array("column1", "column2", "column3")
val df=sc.parallelize(Seq(
(1,"example1", Seq(0,2,5)),
(2,"example2", Seq(1,20,5)))).toDF(columns)
How can I set column name using string Array? Is it possible to mention data types inside toDF()?
如何使用字符串数组设置列名？是否可以在 toDF() 中提及数据类型？
回答by Tzach Zohar
toDF()takes a repeated parameterof type String, so you can use the _*type annotation to pass a sequence:
toDF()接受一个重复的 type参数String，所以你可以使用_*类型注释来传递一个序列：
val df=sc.parallelize(Seq(
(1,"example1", Seq(0,2,5)),
(2,"example2", Seq(1,20,5)))).toDF(columns: _*)
For more on repeated parameters - see section 4.6.2 in the Scala Language Specification.
有关重复参数的更多信息 - 请参阅Scala 语言规范中的第 4.6.2 节。
回答by anshul_cached
val df=sc.parallelize(Seq(
(1,"example1", Seq(0,2,5)),
(2,"example2", Seq(1,20,5)))).toDF("column1", "column2", "column3")
toDF() takes comma-seperated strings
toDF() 采用逗号分隔的字符串
回答by shakedzy
toDF()is defined in Spark documentationas:
toDF()在Spark 文档中定义为：
def toDF(colNames: String*): DataFrame
And so you need to turn your array to a varargsas also described here. That means you need to do the following:
所以你需要把你的阵列的可变参数的描述也是这里。这意味着您需要执行以下操作：
val columns=Array("column1", "column2", "column3")
val df=sc.parallelize(Seq(
(1,"example1", Seq(0,2,5)),
(2,"example2", Seq(1,20,5)))).toDF(columns: _*)
(Add : _* tocolumnsin toDF)
（添加： _* 到columnsin toDF）
