R语言函数参数 #

add <- function(a, b, c) {
  a + b + c
}

add(1, 2, 3)

greet <- function(name, greeting) {
  paste(greeting, name)
}

greet("张三", "Hello")
greet(n = "张三", g = "Hello")

add <- function(a, b, c) {
  a + b + c
}

add(a = 1, b = 2, c = 3)
add(c = 3, a = 1, b = 2)

add <- function(a, b, c) {
  a + b + c
}

add(1, c = 3, b = 2)

greet <- function(name, greeting = "Hello") {
  paste(greeting, name)
}

greet("张三")
greet("张三", "Hi")

create_vector <- function(n = 5, value = 0) {
  rep(value, n)
}

create_vector()
create_vector(10)
create_vector(10, 1)
create_vector(value = 1)

current_time <- function(format = "%Y-%m-%d %H:%M:%S") {
  format(Sys.time(), format)
}

current_time()
current_time("%Y年%m月%d日")

process <- function(data, transform = NULL) {
  if (!is.null(transform)) {
    data <- transform(data)
  }
  data
}

process(c(1, 2, 3))
process(c(1, 2, 3), log)

sum_all <- function(...) {
  args <- list(...)
  sum(unlist(args))
}

sum_all(1, 2, 3, 4, 5)

print_args <- function(...) {
  args <- list(...)
  for (name in names(args)) {
    cat(name, "=", args[[name]], "\n")
  }
}

print_args(a = 1, b = 2, c = 3)

my_mean <- function(x, ...) {
  mean(x, ...)
}

my_mean(c(1, 2, NA, 4), na.rm = TRUE)

my_func <- function(a, b = 10, ...) {
  extra <- list(...)
  list(a = a, b = b, extra = extra)
}

my_func(1, 2, c = 3, d = 4)

greet <- function(name) {
  if (missing(name)) {
    print("Hello, stranger!")
  } else {
    print(paste("Hello,", name))
  }
}

greet()
greet("张三")

calculate <- function(x, multiplier) {
  if (missing(multiplier)) {
    multiplier <- 2
  }
  x * multiplier
}

calculate(10)
calculate(10, 5)

add_numbers <- function(a, b) {
  if (!is.numeric(a) || !is.numeric(b)) {
    stop("参数必须是数值类型")
  }
  a + b
}

add_numbers(1, 2)

set_age <- function(age) {
  if (age < 0 || age > 150) {
    stop("年龄必须在0-150之间")
  }
  age
}

set_age(25)

set_gender <- function(gender) {
  valid <- c("男", "女", "M", "F")
  if (!gender %in% valid) {
    stop("性别必须是: 男, 女, M, F")
  }
  gender
}

set_gender("男")

validate_input <- function(x, type = "numeric", min_val = NULL, max_val = NULL) {
  if (type == "numeric" && !is.numeric(x)) {
    stop("输入必须是数值类型")
  }
  
  if (!is.null(min_val) && any(x < min_val)) {
    stop(paste("值不能小于", min_val))
  }
  
  if (!is.null(max_val) && any(x > max_val)) {
    stop(paste("值不能大于", max_val))
  }
  
  TRUE
}

validate_input(c(1, 2, 3), min_val = 0, max_val = 10)

f <- function(a, b) {
  print("开始执行")
  print(a)
  print(b)
}

f(1, stop("错误"))

f <- function(a, b = a * 2) {
  print(a)
  print(b)
}

f(5)

my_plot <- function(x, y = NULL, type = "p", main = "", 
                    xlab = "x", ylab = "y", ...) {
  if (is.null(y)) {
    y <- x
    x <- 1:length(x)
  }
  
  plot(x, y, type = type, main = main, xlab = xlab, ylab = ylab, ...)
}

my_plot(1:10)
my_plot(1:10, type = "l", col = "red")

process_data <- function(data, 
                         remove_na = TRUE,
                         normalize = FALSE,
                         log_transform = FALSE) {
  if (remove_na) {
    data <- na.omit(data)
  }
  
  if (log_transform) {
    data <- log(data)
  }
  
  if (normalize) {
    data <- (data - min(data)) / (max(data) - min(data))
  }
  
  data
}

x <- c(1, 2, NA, 4, 5)
process_data(x)
process_data(x, normalize = TRUE)

stat_summary <- function(x, 
                         stats = c("mean", "sd", "min", "max"),
                         na.rm = TRUE,
                         digits = 2) {
  result <- list()
  
  for (stat in stats) {
    result[[stat]] <- switch(stat,
      "mean" = round(mean(x, na.rm = na.rm), digits),
      "sd" = round(sd(x, na.rm = na.rm), digits),
      "min" = min(x, na.rm = na.rm),
      "max" = max(x, na.rm = na.rm),
      "median" = median(x, na.rm = na.rm),
      NA
    )
  }
  
  as.data.frame(result)
}

stat_summary(c(1, 2, 3, 4, 5))
stat_summary(c(1, 2, 3, 4, 5), stats = c("mean", "median"))