我已将 JSON 文件读入 Spark。该文件具有以下结构:
scala> tweetBlob.printSchema
root
|-- related: struct (nullable = true)
| |-- next: struct (nullable = true)
| | |-- href: string (nullable = true)
|-- search: struct (nullable = true)
| |-- current: long (nullable = true)
| |-- results: long (nullable = true)
|-- tweets: array (nullable = true)
| |-- element: struct (containsNull = true)
| | |-- cde: struct (nullable = true)
...
...
| | |-- cdeInternal: struct (nullable = true)
...
...
| | |-- message: struct (nullable = true)
...
...
我理想地想要的是一个带有“cde”、“cdeInternal”、“message”列的 DataFrame...如下所示
root
|-- cde: struct (nullable = true)
...
...
|-- cdeInternal: struct (nullable = true)
...
...
|-- message: struct (nullable = true)
...
...
我设法使用“explode”将“tweets”数组中的元素提取到名为“tweets”的列中
scala> val tweets = tweetBlob.select(explode($"tweets").as("tweets"))
tweets: org.apache.spark.sql.DataFrame = [tweets: struct<cde:struct<author:struct<gender:string,location:struct<city:string,country:string,state:string>,maritalStatus:struct<evidence:string,isMarried:string>,parenthood:struct<evidence:string,isParent:string>>,content:struct<sentiment:struct<evidence:array<struct<polarity:string,sentimentTerm:string>>,polarity:string>>>,cdeInternal:struct<compliance:struct<isActive:boolean,userProtected:boolean>,tracks:array<struct<id:string>>>,message:struct<actor:struct<displayName:string,favoritesCount:bigint,followersCount:bigint,friendsCount:bigint,id:string,image:string,languages:array<string>,link:string,links:array<struct<href:string,rel:string>>,listedCount:bigint,location:struct<displayName:string,objectType:string>,objectType:string,postedTime...
scala> tweets.printSchema
root
|-- tweets: struct (nullable = true)
| |-- cde: struct (nullable = true)
...
...
| |-- cdeInternal: struct (nullable = true)
...
...
| |-- message: struct (nullable = true)
...
...
如何选择结构内的所有列并从中创建一个 DataFrame?如果我的理解是正确的,爆炸不适用于结构。
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