Cant save ggplot graphs while using a loop in R-CodePudding

For some reason, I can't figure out, why when I run a ggplot loop to create multiple graphs I don't see them in the environment and hence can't further display the graphs. Data sample.

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)
  
  
}

CodePudding user response：

The graphname is out of scope.

You need to declare it outside the loop.

For example

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)
  
  
}

CodePudding user response：

I assume that you want to assign to a variable, whose name is paste0(title, "_", "Graph"), the value of the plot. If this is correct, you should use 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"

CodePudding user response：

This is probably a better way to do what you are trying to do. You can mapply over your vectors of titles and exposures, which will return a list of graphs you can then refer to by name:

graphs <- mapply(X=exposure_title,Y=exposure_vector, function(X,Y){
  
  ggplot(db,aes(x=get(Y),y=outcome)) 
    geom_smooth() 
    theme_bw() 
    ylab("outcome") 
    xlab("exposure") 
    ggtitle(X)

}, SIMPLIFY = FALSE )

graphs$Pesticide

graphs$Apple