Question

我正在尝试使用spark sql读取Json并打印值

实际上我只想选择数组的第0个元素

当我尝试选择完整的数组时，它可以工作，但是当我尝试从数组中选择第0个元素时它会失败

val events = sc.parallelize("""{"toid":"osgb4000000031043205","point":[508180.748,195333.973],"index":1}""" :: Nil)

 val schema = new StructType().add("toid",StringType,true).add("point",DataTypes.createArrayType(DoubleType,true),true).add("index",StringType,true)

val df = sqlContext.read.schema(schema).json(events)

df.show 

 +--------------------+--------------------+-----+
 |                toid|               point|index|
 +--------------------+--------------------+-----+
 |osgb4000000031043205|[508180.748, 1953...|    1|
 +--------------------+--------------------+-----+


scala> df.select("point")[0].show
<console>:1: error: identifier expected but integer literal found.
   df.select("point")[0].show
                      ^

scala> df.select("point")(0).show
<console>:48: error: type mismatch;
 found   : Int(0)
 required: String
          df.select("point")(0).show

有人可以帮我解决这个错误吗？

Answer 1

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select

您甚至可以使用别名

创建列名

df.select($"point"(0)).show

我希望答案很有帮助

从spark sq中选择特定元素时出错

1 个答案: