从 R 函数返回图

Question

为什么我的 R 函数不会返回或打印绘图？代码如下。除了情节之外，所有代码似乎都可以正常工作。无论我做什么，当函数被调用时，我都无法让 R 创建绘图。在网上环顾四周，我找不到任何不起作用的原因。

powerc.fun <- function(n,sigma,r){

a <- 0.05
d <- seq(-20,20,2)

power <- rep(NA,length(d))
p.lab <- rep(NA,length(d))

for (j in 1:length(d)){

  mu1 <- 110
  mu2 <- mu1-d[j]  

  reject <- rep(NA,r)

  for (i in 1:r){

    sample1 <- rnorm(n,mu1,sigma)
    sample2 <- rnorm(n,mu2,sigma)

    sample.t <- t.test(sample1,sample2)
    p.val <- sample.t[3]

    reject[i] <- p.val<a 

    power[j] <- sum(reject)/length(reject)
    p.lab[j] <- paste('d=',d[j],sep='')

  }}

d.power <- cbind(d,power)

return(d.power)

p.plot <- plot(d.power[,1], d.power[,2], type="l", xlab=bquote(H[a]), ylab="Power", main="Power Calculations for Two Sample T Test")

print(p.plot)
return(p.plot)

}

有任何想法吗？

Answer 1

这有效。根据建议，您可以使用列表保存多个对象:

powerc.fun <- function(n,sigma,r){

a <- 0.05
d <- seq(-20,20,2)

power <- rep(NA,length(d))
p.lab <- rep(NA,length(d))

for (j in 1:length(d)){

  mu1 <- 110
  mu2 <- mu1-d[j]  

  reject <- rep(NA,r)

  for (i in 1:r){

    sample1 <- rnorm(n,mu1,sigma)
    sample2 <- rnorm(n,mu2,sigma)

    sample.t <- t.test(sample1,sample2)
    p.val <- sample.t[3]

    reject[i] <- p.val<a 

    power[j] <- sum(reject)/length(reject)
    p.lab[j] <- paste('d=',d[j],sep='')

  }}

d.power <- cbind(d,power)
p.plot <- plot(d.power[,1], d.power[,2], type="l", xlab=bquote(H[a]), ylab="Power", main="Power Calculations for Two Sample T Test")

return(list(p.plot, d.power))

}

# prints the plot and saves d.power values
output <- powerc.fun(100,0.1,10)

# d.power values
output[[2]]

但可能你更喜欢保存 d.power然后调用它来绘制图形:

powerc.fun <- function(n,sigma,r){

a <- 0.05
d <- seq(-20,20,2)

power <- rep(NA,length(d))
p.lab <- rep(NA,length(d))

for (j in 1:length(d)){

  mu1 <- 110
  mu2 <- mu1-d[j]  

  reject <- rep(NA,r)

  for (i in 1:r){

    sample1 <- rnorm(n,mu1,sigma)
    sample2 <- rnorm(n,mu2,sigma)

    sample.t <- t.test(sample1,sample2)
    p.val <- sample.t[3]

    reject[i] <- p.val<a 

    power[j] <- sum(reject)/length(reject)
    p.lab[j] <- paste('d=',d[j],sep='')

  }}

d.power <- cbind(d,power)

return(d.power)

}

# saves d.power
output <- powerc.fun(100,0.1,10)

# plot
p.plot <- plot(output[,1], output[,2], type="l", xlab=bquote(H[a]), ylab="Power", main="Power Calculations for Two Sample T Test")