Apotex Research CRA Interview Questions and Answers

To rename a column in PySpark, use the 'withColumnRenamed' method.

• Use the 'withColumnRenamed' method on the DataFrame

• Specify the current column name and the new column name as arguments

• Assign the result to a new DataFrame to store the renamed column

Multiprocessing involves executing multiple processes simultaneously, while multithreading involves executing multiple threads within a single process.

• Multiprocessing utilizes multiple CPUs or cores to execute multiple processes concurrently.

• Multithreading involves creating multiple threads within a single process to execute tasks concurrently.

• Processes in multiprocessing have separate memory spaces, while threads in m...read more

ALL returns all rows, UNION removes duplicates, DISTINCT returns unique rows.

• ALL: includes all rows, even duplicates

• UNION: combines two result sets and removes duplicates

• DISTINCT: returns only unique rows

• Example: SELECT name FROM table1 UNION SELECT name FROM table2;

• Example: SELECT name FROM table1 UNION ALL SELECT name FROM table2;

• Example: SELECT DISTINCT name FROM table1;

Convert dictionary to list and sort in ascending order

• Use the items() method to convert dictionary to list of tuples

• Use the sorted() function to sort the list of tuples

• Use a lambda function to sort by dictionary values

• Convert the sorted list of tuples back to a dictionary using dict() method