Data Science Trainee Interview Questions and Answers

SQL Joins are used to combine rows from two or more tables based on a related column between them.

• INNER JOIN: Returns rows when there is at least one match in both tables.

• LEFT JOIN: Returns all rows from the left table and the matched rows from the right table.

• RIGHT JOIN: Returns all rows from the right table and the matched rows from the left table.

• FULL JOIN: Returns rows when there is a match in one of the tables.

Python array is a data structure that stores a collection of elements of the same data type.

• Python array is a mutable sequence type that can store elements of the same data type.

• Arrays in Python are created using the 'array' module.

• Example: arr = array('i', [1, 2, 3, 4, 5])

Supervised ML uses labeled data to train the model, while unsupervised ML finds patterns in unlabeled data.

• Supervised ML requires labeled data for training and testing

• Examples of supervised ML include classification and regression algorithms

• Unsupervised ML finds patterns and relationships in unlabeled data

• Examples of unsupervised ML include clustering and dimensionality reduction algorithms