Branches of mechanical engineering: Conditional Execution Exercises + Solutions - R

(This article was commencement published on R-exercises, in addition to kindly contributed to R-bloggers)

In the exercises below nosotros comprehend the basics of conditional execution. In all previous exercises, the solutions required 1 or to a greater extent than R statements that were all executed consecutively. In this serial of exercises we’re going to usage the if, else and ifelse functions, to execute solely a subset of the R script, depending on 1 or to a greater extent than conditions. Before proceeding, commencement read department 9.2.1 of An Introduction to R, in addition to the aid pages for the if and ifelse functions.

Answers to the exercises are available here.

Many of the exercises below could endure solved using touchstone functions, like maxor abs. For the purpose of these exercises, however, avoid these functions in addition to crusade to solve each occupation using conditional execution.

Exercise 1
Create an R script that returns the absolute value of an integer vector x.

Exercise 2
Create an R script that calculates the foursquare root of a given integer vector x of length one, if the value contained in x is negative it should return NA.

Exercise 3
Create an R script that returns the maximum value out of the elements of a numeric vector x of length 2.

Exercise 4
Create an R script that returns TRUE if the elements of a vector x, amongst length 3, are strictly increasing.

Exercise 5
Create an R script that returns the max value of a vector x with length 3. Don’t usage the assist of an auxiliary variable.

Exercise 6
Create an R script that returns the total of values that are larger than the hateful of a vector. You are allowed to use mean().

Exercise 7
Create an R script that, given a numeric vector x with length 3, volition impress the elements past times companionship from high to low.

Image past times Ambigraphe (Own work) [GFDL or CC BY-SA 3.0], via Wikimedia Commons

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Below are the solutions to these exercises on conditional execution.

# Exercise 1  x <- -10 abs <- x if (x < 0) {     abs = -x } cat("The absolute value of ", x, " is ", abs , "\n" ) 

## The absolute value of  -10  is  10 

# Exercise two  x <- 16 y <- ifelse(x >= 0, x, NA) cat("The foursquare root of",  x, "is", sqrt(y)) 

## The foursquare root of xvi is iv 

# Exercise three  x <- c(10, 1) if(x[1] > x[2]) {     cat("Max value is", x[1], "\n") } else cat("Max value is", x[2], "\n") 

## Max value is 10 

# Exercise iv  x <- c(10, 11, 12) grow <- FALSE  ifelse ( ( (x[1] < x[3] & x[1] < x[2]) & x[2] < x[3]), grow <- TRUE, grow) 

## [1] TRUE 

if (grow){     cat ("Increasing strictly \n") } else cat ("Not increasing strictly \n") 

## Increasing strictly 

# Exercise five  x <- c(20, 10, 1)  if (x[1] > x[2] & x[1] > x[3] ) {     cat (x[1], "\n" ) } else if (x[2] > x[3] ) {     cat (x[2] , "\n" ) } else {     cat (x[3] , "\n" ) } 

## twenty 

# Exercise vi  x <- c(-100, 10, 20, 30, 50, 51, 52, 53, 54, 55) counter <- 0 mean <- mean(x)  for (i in 1:length(x)){      if(x[i] > mean){         counter <- counter +1     } }  cat("The issue of values that are bigger than the hateful is", counter, "\n") 

## The issue of values that are bigger than the hateful is vii 

# Exercise vii  x <- c(30, 120, 100)  if (x[1] > x[2]){     fir <- x[1]     sec <- x[2] } else {     fir <- x[2]     sec <- x[1] } if ( x[3] > fir & x[3] > sec ) {     thi <- sec     sec <- fir     fir <- x[3] } else if ( x[3] < fir & x[3] < sec ) {     thi <- x[3] } else {     thi <- sec     sec <- x[3] } cat (fir, sec, thi, "\n") 

## 120 100 30

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Sources:

http://www.r-exercises.com/2016/01/26/conditional-execution-exercises-solutions/

http://www.r-exercises.com/2016/01/26/conditional-execution-exercises/

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