R Basics

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Problem 1:

  1. From set = {1.5, 15, 0, 54, 23}, pick two numbers and perform the Following Operations:

.Subtraction .Multiplication .square root

# creates the dataset
SetProblem1 <- c(1.5, 15, 0, 54, 23)
# subtracts 4th position from the 2nd
SetProblem1[2] - SetProblem1[4]
## [1] -39
# multiplies the 4th position with the 2nd
SetProblem1[2] * SetProblem1[4]
## [1] 810
# squareroot 4th and 2nd positions in th dataset
sqrt(SetProblem1[2])
## [1] 3.872983
sqrt(SetProblem1[4])
## [1] 7.348469

Problem 2

Suppose you have a set of numbers representing the assignments scores:

scores <- c(87,100, 91, 95, 81.5, 0, 39, 74, 92)

#Calculate the average of the scores, and round your answer to two decimal number
mean(scores)
## [1] 73.27778
#Find the Maximum and Minimum score
max(scores)
## [1] 100
min(scores)
## [1] 0
#Find how many scores were above the average, use coding for this
scores[scores > mean(scores)]
## [1]  87.0 100.0  91.0  95.0  81.5  74.0  92.0
#create a new set of scores, call it new_scores.  The new list should include elements 2 to 6
new_scores <- scores[c(2, 6)]
new_scores
## [1] 100   0

Problem 3: Read section 2.3

# Create a vector with the number 1 repeated 5 times. Print it
five_ones <- rep(1, times = 5)
five_ones
## [1] 1 1 1 1 1
# Create a vector with a sequence of numbers from 1 to 10 with a step of 2. Print it
Sequence_1_to_10 <- seq(from = 1, to = 10, by = 2)
Sequence_1_to_10
## [1] 1 3 5 7 9
# Create a vector by repeating a sequence from 1 to 3, 2 times. call it
Sequence_1_to_3_2_times <- rep(1:3, times = 2)
Sequence_1_to_3_2_times
## [1] 1 2 3 1 2 3

Problem 4

# Create a vector with different class types
mixed_vector <- c(1, "two", 3.0, TRUE, 2)
mixed_vector
## [1] "1"    "two"  "3"    "TRUE" "2"
# Check the class of the vector
class(mixed_vector)
## [1] "character"
## Coerce to numeric and print it 
To_numeric <- as.numeric(mixed_vector)
## Warning: NAs introduzidos por coerção
To_numeric
## [1]  1 NA  3 NA  2