How do I create a list of ggplots?

user_11117255 0
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I have these three data frames and this function

set.seed(1)
df1 <-
  data.frame(
    x = c("cat", "dog"),
    y = sample(1:100, 20),
    z = seq(ymd("2020-01-01"), ymd("2020-01-20"), by = "1 day")
  )

df2 <-
  data.frame(
    x = c("red", "green"),
    y = sample(1:100, 20),
    z = seq(ymd("2020-01-01"), ymd("2020-01-20"), by = "1 day")
  )

df3 <-
  data.frame(
    x = c("up", "down"),
    y = sample(1:100, 20),
    z = seq(ymd("2020-01-01"), ymd("2020-01-20"), by = "1 day")
  )


dataframes <-
  c("df1", "df2", "df3")

exploreDataFrames <- function(dataframes, sequence = seq_along(dataframes)){
  
  for (i in seq_along(sequence)){
    print(get(dataframes[i]))
    
    gg <-
      get(dataframes[i]) %>% 
      ggplot(aes(z, y, group = 1)) +
      geom_line() +
      facet_wrap(~get(names(get(dataframes[i]))[1]))
    
    return(gg)
  }
}

exploreDataFrames(dataframes[3])

I'd like for my function to return a list with three entries:

list[1][1] <- name_of_the_dataframe
list[1][2] <- copy_of_the_complete_dataframe
list[1][3] <- ggplot_object

My goal is to be able to have a single list and iterate through the ggplot charts, quickly be able to slice it by the name of a particular data frame and pull up the complete dataframe.

What do I need to change about my function to make this possible?

ggplot2 r
3 Answers

You can use

l = sapply(dataframes, function (dfname) {
      ggplot(get(dfname) , aes(z, y, group = 1)) +
      geom_line() +
      facet_wrap(~get(names(get(dfname))[1]))
    }, simplify = FALSE, USE.NAMES = TRUE)

the data.frame names are then in names(l)

names(l[1])
# [1] "df1"

and the data are in

l[[1]]$data

#     x  y          z
#1  cat 68 2020-01-01
#2  dog 39 2020-01-02
#3  cat  1 2020-01-03
#4  dog 34 2020-01-04
#5  cat 87 2020-01-05
#6  dog 43 2020-01-06
#7  cat 14 2020-01-07
#8  dog 82 2020-01-08
#9  cat 59 2020-01-09
#10 dog 51 2020-01-10
#11 cat 85 2020-01-11
#12 dog 21 2020-01-12
#13 cat 54 2020-01-13
#14 dog 74 2020-01-14
#15 cat  7 2020-01-15
#16 dog 73 2020-01-16
#17 cat 79 2020-01-17
#18 dog 37 2020-01-18
#19 cat 83 2020-01-19
#20 dog 97 2020-01-20
user_27615750

You need to initiate the whole list before starting to populate it. Since you have a nested level in the list, you need to initiate that "inner" list too:

set.seed(1)
df1 <-
  data.frame(
    x = c("cat", "dog"),
    y = sample(1:100, 20),
    z = seq(ymd("2020-01-01"), ymd("2020-01-20"), by = "1 day")
  )
df2 <-
  data.frame(
    x = c("red", "green"),
    y = sample(1:100, 20),
    z = seq(ymd("2020-01-01"), ymd("2020-01-20"), by = "1 day")
  )

df3 <-
  data.frame(
    x = c("up", "down"),
    y = sample(1:100, 20),
    z = seq(ymd("2020-01-01"), ymd("2020-01-20"), by = "1 day")
  )


dataframes <-
  c("df1", "df2", "df3")

exploreDataFrames <- function(dataframes, sequence = seq_along(dataframes)){
  
  ll <- list()
  
  for (i in seq_along(sequence)){
    ll[[i]] <- list()
    ll[[i]][[1]] <- dataframes[i]
    # print(get(dataframes[i]))
    ll[[i]][[2]] <- get(dataframes[i])
    ll[[i]][[3]] <- 
      get(dataframes[i]) %>% 
      ggplot(aes(z, y, group = 1)) +
      geom_line() +
      facet_wrap(~get(names(get(dataframes[i]))[1]))
    
  }
  return(ll)
}

out <- exploreDataFrames(dataframes)
user_38900270

To return the list the question asks for, create a list to hold the objects before the for loop, with the length set to length(sequence) and assign the values in the loop.

exploreDataFrames <- function(dataframes, sequence = seq_along(dataframes)){
  
  out_list <- vector("list", length = length(sequence))
  for (i in seq_along(sequence)){
    dftmp <- get(dataframes[i])
    print(dftmp)
    
    gg <-
      dftmp %>% 
      ggplot(aes(z, y, group = 1)) +
      geom_line() +
      facet_wrap(~get(names(dftmp)[1]))
    
    out_list[[i]]$data.name <- dataframes[i]
    out_list[[i]]$data <- dftmp
    out_list[[i]]$gg.plot <- gg
  }
  out_list
}

exploreDataFrames(dataframes[3])

This will plot the out_list[[1]]$gg.plot object, since the function's return value is not assigned to anything, it's returned to the .GlobalEnv.

user_82454060
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