我在 R 中使用 par() 制作了两个图，但它没有保存

Question

我创建了一个函数，读取 csv 文件，将数据处理到数据框中，在 (2,1) 布局中制作箱线图和条形图，然后保存在 png 文件中。如果我运行一个函数，它确实会显示正确的数据框，但绘图不会保存。如果我独立运行绘图代码，Rstudio 会正确显示绘图。请帮忙...

data <- read.csv("file name here", stringsAsFactors = FALSE)

F4 <- function(data) {
  data <- data[, !colnames(data) %in% "blank"]
  names(data) <- c("district", "confirmed", "deceased", "recovered")
  data[,"active"] <- data$confirmed - data$recovered - data$deceased
  data <- data[, c("district", "active", "confirmed", "recovered", "deceased")]
  data <- data[1:30, ]
  return(data)
  
  png("png file name here", width=100, height=500)
  
  par(mfrow = c(2, 1), mar = c(4, 4, 4, 4), oma = c(0, 0, 0, 0))
  boxplot(data$active, data$confirmed, data$recovered, data$deceased, col = "skyblue", ylab = "No. of Cases",
          main = "Boxplot of COVID-19 status")
  axis(1, at = 1, labels = "Active")
  axis(1, at = 2, labels = "Confirmed")
  axis(1, at = 3, labels = "Recovered")
  axis(1, at = 4, labels = "Deceased")
  barplot(data$confirmed, col = "skyblue", ylim = c(0, 200), names.arg = 1:30,
          xlab = "District", ylab = "No. of Cases", main = "COVID-19 status by region")
  barplot(data$recovered, col = "yellowgreen", add = TRUE)
  barplot(data$deceased, col = "tomato", add = TRUE)
  legend("topright", legend = c("Confirmed", "Recovered", "Deceased"), fill=c("skyblue", "yellowgreen", "tomato"), horiz=TRUE, cex = 0.9)
  
  dev.off()
}

如果我独立运行绘图代码，Rstudio 会正确显示绘图。请帮忙...

Answer 1

F4 <- function(data) {
  data <- data[, !colnames(data) %in% "blank"]
  names(data) <- c("district", "confirmed", "deceased", "recovered")
  data[, "active"] <- data$confirmed - data$recovered - data$deceased
  data <- data[, c("district", "active", "confirmed", "recovered", "deceased")]
  data <- data[1:30, ]
  png("foo.png", 800, 1000)
  par(mfrow=c(2, 1), mar=c(4, 4, 4, 4), oma=c(0, 0, 0, 0))
  boxplot(data$active, data$confirmed, data$recovered, data$deceased,
          col="skyblue", ylab="No. of Cases", 
          main="Boxplot of COVID-19 status")
  axis(1, at=1, labels="Active")
  axis(1, at=2, labels="Confirmed")
  axis(1, at=3, labels="Recovered")
  axis(1, at=4, labels="Deceased")
  barplot(data$confirmed, col="skyblue", ylim=c(0, 200), names.arg=1:30, 
          xlab="District", ylab="No. of Cases",
          main="COVID-19 status by region")
  barplot(data$recovered, col="yellowgreen", add=TRUE)
  barplot(data$deceased, col="tomato", add=TRUE)
  legend("topright", legend=c("Confirmed", "Recovered", "Deceased"), 
         fill=c("skyblue", "yellowgreen", "tomato"), horiz=TRUE, cex=0.9)
  dev.off()
  return(data)
}