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R for Data Analytics MCQ - Advanced R Programming

1 Which function is most appropriate for applying a function to every element of a list and returning a list?

lapply() applies a function to each element of a list and returns the results as a list.

2 What is returned by sapply() when the results can be simplified?

sapply() works like lapply() but attempts to simplify the result to a vector or matrix.

3 Which function applies a function over the margins of an array or matrix?

apply() applies a function over specified rows, columns, or other margins of an array.

4 What does apply(x, 1, mean) calculate when x is a numeric matrix?

In apply(), margin 1 represents rows, so the mean is calculated for each row.

5 What does apply(x, 2, sum) calculate for a matrix x?

Margin 2 in apply() represents columns.

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Question:

Why is set.seed() commonly used before operations involving random numbers?

A. To increase randomness
B. To make random results reproducible
C. To remove duplicated values
D. To convert numbers to integers

Correct answer: B

Explanation:

set.seed() initializes the random number generator so the same random sequence can be reproduced.

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