R is a programming language and environment for statistical computing and graphics. It is widely used in data analysis, machine learning, and scientific research. R was created by Ross Ihaka and Robert Gentleman at the University of Auckland, New Zealand in 1993.
R variables can store a variety of data types, including numeric, character, logical, and complex. Variables are assigned using the <- or = operator.
# Numeric variable
x <- 3.14
# Character variable
name <- "Alice"
# Logical variable
is_female <- TRUE
# Complex variable
z <- 1 + 2i
R has a large number of built-in functions for common tasks such as data manipulation, statistical analysis, and plotting. Functions are called by name, with arguments in parentheses.
# Data manipulation
mean(c(1, 2, 3, 4, 5)) # Returns 3
# Statistical analysis
t.test(c(1, 2, 3, 4, 5), mu=3) # One-sample t-test
# Plotting
plot(c(1, 2, 3, 4, 5), c(1, 4, 9, 16, 25), type="l")
R has several types of loops, including for, while, and repeat. The for loop is used to iterate over a sequence of values, while the while and repeat loops are used to repeat a block of code while a condition is true or false.
# For loop
for (i in 1:10) {
print(i)
}
# While loop
i <- 1
while (i <= 10) {
print(i)
i <- i + 1
}
# Repeat loop
i <- 1
repeat {
print(i)
i <- i + 1
if (i > 10) {
break
}
}
R has several conditional statements, including if, else if, and else. These statements are used to control the flow of a program based on certain conditions.
# If statement
age <- 30
if (age >= 18) {
print("You are an adult")
}
# If-else statement
age <- 15
if (age >= 18) {
print("You are an adult")
} else {
print("You are a minor")
}
# If-else if-else statement
age <- 25
if (age < 18) {
print("You are a minor")
} else if (age < 65) {
print("You are an adult")
} else {
print("You are a senior")
}
R provides several functions for manipulating files, including read.csv, write.csv, file.rename, and file.remove.
# Read CSV file
data <- read.csv("data.csv")
# Write CSV file
write.csv(data, "data_new.csv")
# Rename file
file.rename("data.csv", "data_old.csv")
# Remove file
file.remove("data_old.csv")