apache-spark - 如何检查 Spark 中两个 DataFrame 列的交集

Question

使用 pyspark或 sparkr (最好是两者)，我怎样才能得到两个的交集DataFrame列？例如，在 sparkr我有以下 DataFrames :

newHires <- data.frame(name = c("Thomas", "George", "George", "John"),
                       surname = c("Smith", "Williams", "Brown", "Taylor"))
salesTeam <- data.frame(name = c("Lucas", "Bill", "George"),
                        surname = c("Martin", "Clark", "Williams"))
newHiresDF <- createDataFrame(newHires)
salesTeamDF <- createDataFrame(salesTeam)

#Intersect works for the entire DataFrames
newSalesHire <- intersect(newHiresDF, salesTeamDF)
head(newSalesHire)

        name  surname
    1 George Williams

#Intersect does not work for single columns
newSalesHire <- intersect(newHiresDF$name, salesTeamDF$name)
head(newSalesHire)

Error in as.vector(y) : no method for coercing this S4 class to a vector

我怎样才能得到intersect为单列工作？

Answer 1

您需要两个 Spark DataFrame 才能使用 intersect 函数。您可以使用 select 函数从每个 DataFrame 中获取特定列。

在 SparkR 中:

newSalesHire <- intersect(select(newHiresDF, 'name'), select(salesTeamDF,'name'))

在pyspark中:

newSalesHire = newHiresDF.select('name').intersect(salesTeamDF.select('name'))