UPDATE:使用 “单义性” 解析器的lib我可以摆脱一个行,其中我在列名删除空格的:
斯卡拉:
// read Spark Output Fixed width table:
def readSparkOutput(filePath: String) : org.apache.spark.sql.DataFrame = {
val t = spark.read
.option("header","true")
.option("inferSchema","true")
.option("delimiter","|")
.option("parserLib","UNIVOCITY")
.option("ignoreLeadingWhiteSpace","true")
.option("ignoreTrailingWhiteSpace","true")
.option("comment","+")
.csv(filePath)
t.select(t.columns.filterNot(_.startsWith("_c")).map(t(_)):_*)
}
PySpark:
def read_spark_output(file_path):
t = spark.read \
.option("header","true") \
.option("inferSchema","true") \
.option("delimiter","|") \
.option("parserLib","UNIVOCITY") \
.option("ignoreLeadingWhiteSpace","true") \
.option("ignoreTrailingWhiteSpace","true") \
.option("comment","+") \
.csv("file:///tmp/spark.out")
# select not-null columns
return t.select([c for c in t.columns if not c.startswith("_")])
使用示例:
scala> val df = readSparkOutput("file:///tmp/spark.out")
df: org.apache.spark.sql.DataFrame = [col1: int, col2: string ... 1 more field]
scala> df.show
+----+---------+--------+
|col1| col2| col3|
+----+---------+--------+
| 1|pi number|3.141592|
| 2| e number| 2.71828|
+----+---------+--------+
scala> df.printSchema
root
|-- col1: integer (nullable = true)
|-- col2: string (nullable = true)
|-- col3: double (nullable = true)
老答案:
这是我在斯卡拉尝试(星火2.2):
// read Spark Output Fixed width table:
val t = spark.read
.option("header","true")
.option("inferSchema","true")
.option("delimiter","|")
.option("comment","+")
.csv("file:///temp/spark.out")
// select not-null columns
val cols = t.columns.filterNot(c => c.startsWith("_c")).map(a => t(a))
// trim spaces from columns
val colsTrimmed = t.columns.filterNot(c => c.startsWith("_c")).map(c => c.replaceAll("\\s+",""))
// reanme columns using 'colsTrimmed'
val df = t.select(cols:_*).toDF(colsTrimmed:_*)
它的工作原理,但我有一种感觉,必须有多少更优雅的方式来做到这一点。
scala> df.show
+----+---------+--------+
|col1| col2| col3|
+----+---------+--------+
| 1.0|pi number|3.141592|
| 2.0| e number| 2.71828|
+----+---------+--------+
scala> df.printSchema
root
|-- col1: double (nullable = true)
|-- col2: string (nullable = true)
|-- col3: double (nullable = true)
我一直在想写一个自定义的Spark源码,但是你的解决方案很简单!谢谢。 –
@JacekLaskowski,不,谢谢!我从你的[掌握Apache Spark 2](https://www.gitbook.com/book/jaceklaskowski/mastering-apache-spark/details)以及从你的答案中学到很多东西。 – MaxU