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Databricks Exam Databricks Certified Associate Developer for Apache Spark 3.0 Topic 3 Question 70 Discussion

Actual exam question for Databricks's Databricks Certified Associate Developer for Apache Spark 3.0 exam
Question #: 70
Topic #: 3
[All Databricks Certified Associate Developer for Apache Spark 3.0 Questions]

The code block displayed below contains an error. The code block should return a copy of DataFrame transactionsDf where the name of column transactionId has been changed to

transactionNumber. Find the error.

Code block:

transactionsDf.withColumn("transactionNumber", "transactionId")

Show Suggested Answer Hide Answer
Suggested Answer: A

transactionsDf.select('storeId').dropDuplicates().count()

Correct! After dropping all duplicates from column storeId, the remaining rows get counted, representing the number of unique values in the column.

transactionsDf.select(count('storeId')).dropDuplicates()

No. transactionsDf.select(count('storeId')) just returns a single-row DataFrame showing the number of non-null rows. dropDuplicates() does not have any effect in this context.

transactionsDf.dropDuplicates().agg(count('storeId'))

Incorrect. While transactionsDf.dropDuplicates() removes duplicate rows from transactionsDf, it does not do so taking only column storeId into consideration, but eliminates full row duplicates

instead.

transactionsDf.distinct().select('storeId').count()

Wrong. transactionsDf.distinct() identifies unique rows across all columns, but not only unique rows with respect to column storeId. This may leave duplicate values in the column, making the count

not represent the number of unique values in that column.

transactionsDf.select(distinct('storeId')).count()

False. There is no distinct method in pyspark.sql.functions.


by Lucina at Oct 19, 2024, 03:43 AM

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Floyd
1 months ago
Reordering arguments? That's child's play. I bet the real challenge is figuring out which hand to use when reordering them. *winks*
upvoted 0 times
Dawne
10 days ago
User 3: E) The method withColumn should be replaced by method withColumnRenamed and the arguments to the method need to be reordered.
upvoted 0 times
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Isreal
16 days ago
User 2: B) The arguments to the withColumn method need to be reordered and the copy() operator should be appended to the code block to ensure a copy is returned.
upvoted 0 times
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Natalie
1 months ago
User 1: A) The arguments to the withColumn method need to be reordered.
upvoted 0 times
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Melita
2 months ago
Hold on, I got this! The method withColumn should be replaced by withColumnRenamed, and the arguments need to be reordered. *cracks knuckles* Time to show off my Spark skills.
upvoted 0 times
Jade
14 days ago
B) The arguments to the withColumn method need to be reordered and the copy() operator should be appended to the code block to ensure a copy is returned.
upvoted 0 times
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James
16 days ago
E) The method withColumn should be replaced by method withColumnRenamed and the arguments to the method need to be reordered.
upvoted 0 times
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Eleonore
1 months ago
A) The arguments to the withColumn method need to be reordered.
upvoted 0 times
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Elly
2 months ago
Wrap the column names in the col() method? What is this, some kind of black magic? I'll go with option D, just to be safe.
upvoted 0 times
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Shizue
2 months ago
Hmm, I think the copy() operator should be appended to the code block. Can't be too careful with those DataFrames, you know?
upvoted 0 times
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Skye
2 months ago
The error is obvious! The arguments to the withColumn method need to be reordered. Easy peasy.
upvoted 0 times
Angelo
1 months ago
C) The copy() operator should be appended to the code block to ensure a copy is returned.
upvoted 0 times
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Verona
2 months ago
A) The arguments to the withColumn method need to be reordered.
upvoted 0 times
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Veda
2 months ago
I believe option A) is correct, the arguments need to be reordered.
upvoted 0 times
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Delsie
2 months ago
I agree with Hildegarde, the arguments should be reordered.
upvoted 0 times
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Hildegarde
3 months ago
I think the error is that the arguments need to be reordered.
upvoted 0 times
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