Need to user univariate summary stats

[Arunkumar Pillai]

Hi

I'm currently using query

sqlContext.sql("SELECT MAX(variablesArray) FROM " + tableName)

to extract mean max min.
is there any better  optimized way ?

In the example i saw df.groupBy("key").agg(skewness("a"), kurtosis("a"))


But i don't have key anywhere in the data.

How to extract the univariate summary stats from df. please help

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Thanks and Regards
        Arun