Introduction
data.table is a fast package for data manipulation. It handles large datasets efficiently.
Creating data.table
library(data.table)
# Create data.table
dt <- data.table(
id = 1:5,
name = c("Alice", "Bob", "Charlie"),
value = c(10, 20, 30, 40, 50)
)
# Read from file
fread("data.csv")
Basic Operations
# Select columns
dt[, .(name, value)]
# Filter rows
dt[value > 20]
# Add column
dt[, new_col := value * 2]
# Multiple operations
dt[, .(mean = mean(value)), by = group]
Fast Operations
# Group by
dt[, .(sum = sum(value)), by = group]
# Keys for fast lookup
setkey(dt, id)
dt[J(1)]
# Join
merge(dt1, dt2, by = "id")
Summary
data.table handles large data efficiently. Use it for performance-critical operations.