Learn how to efficiently retrieve the first N rows of a DataFrame in Apache Spark using the correct method. Explore the differences between take(), head(), and collect() functions.
Table of Contents
Question
Which of the following code blocks returns the first 3 rows of DataFrame storesDF?
A. storesDF.top_n(3)
B. storesDF.n(3)
C. storesDF.take(3)
D. storesDF.head(3)
E. storesDF.collect(3)
Answer
D. storesDF.head(3)
Explanation
In Apache Spark, the head() method is used to retrieve the first N rows of a DataFrame. It returns an array containing the first N rows of the DataFrame.
The take(3) method (option C) also returns the first 3 rows, but it returns them as a list, which is less efficient for larger datasets.
The collect(3) method (option E) is incorrect because collect() returns all the rows of the DataFrame as an array to the driver program. It does not accept any arguments to limit the number of rows returned.
Options A and B, top_n(3) and n(3), are not valid DataFrame methods in Apache Spark.
Therefore, storesDF.head(3) is the correct and most efficient way to retrieve the first 3 rows of the DataFrame storesDF.
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