Blog of Andrés Aravena
CMB2:

# Homework 4

26 March 2021. Deadline: Friday, 2 April, 8:59.

# Vector to vector

Write a function that takes a DNA sequence and returns its reverse-complement.

Use it to show that the GC skew of the reverse-complement strand has the same absolute value as the original strand, but opposite sign.

# Vector to value

Make these functions using only for(), if() and indices. You cannot use the words min or max. The input is a vector called x.

Please write the code of the following functions:

1. smallest_value(x). Returns the smallest element in x.

You can test your function with the following code.

x <- c(16, 15, 19, 10, 14, 7, 12, 18, 20, 9)
min(x)
smallest_value(x)

The two results must be the same.

2. largest_value(x). Returns the largest element in x.

You can test your function with the following code.

x <- c(7, 6, 18, 5, 16, 19, 7, 10, 14, 11)
max(x)
largest_value(x)

The two results must be the same.

3. place_of_smallest(x). Returns the index of the smallest element in x.

You can test your function with the following code.

x <- c(17, 12, 5, 6, 14, 15, 20, 13, 9, 20)
which.min(x)
place_of_smallest(x)

The two results must be the same.

4. place_of_largest(x). Returns the index of the largest element in x.

You can test your function with the following code.

x <- c(11, 14, 7, 6, 13, 10, 18, 16, 14, 14)
which.max(x)
place_of_largest(x)

The two results must be the same.