Sample questions

Question 1:

Which of the following code blocks returns a DataFrame showing the mean of the salary column of the df DataFrame, grouped by the department column?

1. df.groupBy("department").agg(avg("salary"))
2. df.groupBy(col(department).avg())
3. df.groupBy("department").avg(col("salary"))
4. df.groupBy("department").agg(average("salary"))

Question 2:

Which of the following code blocks returns unique values across all values in the state and department columns in df?

1. df.select(state).join(transactionsDf.select('department'), col(state)==col('department'), 'outer').show()
2. df.select(col('state'), col('department')).agg({'*': 'count'}).show()
3. df.select('state', 'department').distinct().show()
4. df.select('state').union(df.select('department')).distinct().show()
...