ตัวดำเนินการเลขคณิตและการเปรียบเทียบ

# Basic arithmetic in R
x <- 10
y <- 3
cat('x =', x, ', y =', y, '
')

price <- 49.99
discount <- 5.00
final_price <- price - discount
tax <- final_price + 3.50
cat('Final price with tax:', tax, '
')

width <- 8
height <- 5
area <- width * height
half_area <- area / 2
cat('Area:', area, '
')
cat('Half area:', half_area, '
')
cat('7 / 2 =', 7 / 2, '
')  # returns 3.5

side <- 4
area_square <- side ^ 2
cat('Area of square:', area_square, '
')

base <- 2
cat('2^8 =', base ^ 8, '
')
cat('Square root of 16:', 16 ^ 0.5, '
')

# Check if a number is even or odd
num <- 17
remainder <- num %% 2
cat(num, 'is', ifelse(remainder == 0, 'even', 'odd'), '
')

# Cycle through hours (0-23)
minutes <- 150
hours <- minutes %% 60
cat('150 minutes =', hours, 'minutes past the hour
')

total_items <- 23
box_size <- 5
full_boxes <- total_items %/% box_size
leftover <- total_items %% box_size
cat('Full boxes:', full_boxes, '
')
cat('Leftover items:', leftover, '
')
cat('Check: 7 %/% 2 =', 7 %/% 2, '
')

score <- 85
passing_grade <- 60

cat('Did student pass?', score >= passing_grade, '
')
cat('Is score exactly 100?', score == 100, '
')
cat('Score is not 85?', score != 85, '
')

temp_c <- 37.2
normal_temp <- 37.0

cat('Fever?', temp_c > normal_temp, '
')
cat('Hypothermia?', temp_c < 35.0, '
')
cat('Normal or above?', temp_c >= normal_temp, '
')

# Works on strings too
cat('apple < banana:', 'apple' < 'banana', '
')

ages <- c(12, 25, 17, 34, 8)
cat('Ages:', ages, '
')
cat('Over 18:', ages > 18, '
')
cat('Exactly 17:', ages == 17, '
')

# Count how many are adults
cat('Number of adults:', sum(ages >= 18), '
')

# BMI check
weight_kg <- 70
height_m <- 1.75
bmi <- weight_kg / (height_m ^ 2)
cat('BMI:', round(bmi, 1), '
')
cat('Healthy BMI (18.5-24.9)?', bmi >= 18.5 & bmi <= 24.9, '
')

# Discount eligibility
total <- 120
cat('Qualifies for discount?', total >= 100, '
')

# Quick demo of all operators
x <- 10
y <- 3
cat('10 + 3 =', x + y, '
')
cat('10 - 3 =', x - y, '
')
cat('10 * 3 =', x * y, '
')
cat('10 / 3 =', x / y, '
')
cat('10 %% 3 =', x %% y, '
')
cat('10 %/% 3 =', x %/% y, '
')
cat('10 > 3 =', x > y, '
')

# Final example: find numbers divisible by 3
nums <- 1:15
divisible_by_3 <- nums[nums %% 3 == 0]
cat('Numbers 1-15 divisible by 3:', divisible_by_3, '
')