Calculate mean for several columns in Spark scala

user_3967651 0
Viewed 6902

I'm looking for a way to calculate some statistic e.g. mean over several selected columns in Spark using Scala. Given that data object is my Spark DataFrame, it's easy to calculate a mean for one column only e.g.

data.agg(avg("var1") as "mean var1").show

Also, we can easily calculate a mean cross-tabulated by values of some other columns e.g.:

data.groupBy("category").agg(avg("var1") as "mean_var1").show

But how can we calculate a mean for a List of columns in a DataFrame? I tried running something like this, but it didn't work:

scala> data.select("var1", "var2").mean().show
<console>:44: error: value mean is not a member of org.apache.spark.sql.DataFrame
       data.select("var1", "var2").mean().show
                                   ^
apache-spark scala
2 Answers

If you already have the dataset you can do this:

ds.describe(s"age")

Which will return this:

    summary age  
    count   10.0 
    mean    53.3   
    stddev  11.6
    min     18.0
    max     92.0
user_5115540
Related