在 R 中使用循环时无法保存 ggplot 图答案

【问题标题】：Cant save ggplot graphs while using a loop in R在 R 中使用循环时无法保存 ggplot 图
【发布时间】：2022-12-01 16:43:27
【问题描述】：

出于某种原因，我无法弄清楚，为什么当我运行 ggplot 循环来创建多个图形时，我在环境中看不到它们，因此无法进一步显示图形。数据样本。

db = data.frame(exposure = sample(1:100, 100),
                   exposure2 = sample(-90:100,100),
                   outcome = sample(200:1000,100))

exposure_vector = c("exposure","exposure2")
exposure_title = c("Pesticide","Apple")
for (i in 1:length(exposure_vector)) {
  current_exposure = db[[exposure_vector[i]]]
  title = exposure_title[i]
  graph_name = paste0(title,"_","Graph")
  graph_name=ggplot(db,aes(x=current_exposure,y=outcome))+geom_smooth()+
    theme_bw()+ylab("outcome")+xlab("exposure")+ggtitle(title)
  print(graph_name)
  
  
}

【问题讨论】：

标签： r for-loop ggplot2

【解决方案1】：

graphname 超出范围。

您需要在循环外声明它。

例如

db = data.frame(exposure = sample(1:100, 100),
                exposure2 = sample(-90:100,100),
                outcome = sample(200:1000,100))

exposure_vector = c("exposure","exposure2")
exposure_title = c("Pesticide","Apple")

plot <- list() #declare
for (i in 1:length(exposure_vector)) {
  current_exposure = db[[exposure_vector[i]]]
  title = exposure_title[i]
  graph_name = paste0(title,"_","Graph")
  graph_name=ggplot(db,aes(x=current_exposure,y=outcome))+geom_smooth()+
    theme_bw()+ylab("outcome")+xlab("exposure")+ggtitle(title)
  
  plot[[i]] <- graph_name #write
  print(graph_name)
  
  
}

【讨论】：

【解决方案2】：

我假设您想将绘图的值分配给名称为 paste0(title, "_", "Graph") 的变量。如果这是正确的，你应该使用assign

library(ggplot2)

db <- data.frame(exposure = sample(1:100, 100),
                 exposure2 = sample(-90:100,100),
                 outcome = sample(200:1000,100))

exposure_vector <- c("exposure","exposure2")
exposure_title <- c("Pesticide","Apple")

for (i in 1:length(exposure_vector)) {
  current_exposure <- db[[exposure_vector[i]]]
  title <- exposure_title[i]
  graph_name <- paste0(title,"_","Graph")
  p <- ggplot(db,aes(x=current_exposure,y=outcome))+
      geom_smooth()+
      theme_bw()+
      ylab("outcome")+
      xlab("exposure")+
      ggtitle(title)
  
  assign(graph_name, p)
  print(p)
}

ls()

##> [1] "Apple_Graph"      "current_exposure" "db"               "exposure_title"  
##> [5] "exposure_vector"  "graph_name"       "i"                "p"               
##> [9] "Pesticide_Graph"  "title"

【讨论】：