gen-plot-list.R

library(dplyr)
library(purrr)
library(ggplot2)

#;; Data
df <- tibble(cat=c("A", "A", "B", "B"),
        x=c(1, 2, 1, 2),
        y=c(1, 2, 2, 1))

#;; List of dataframes to plot
listOf_df <- df |> group_by(cat) |> group_split()

#;;-----------------------------------------------------------------------------
#;; With for loop
plotOutput_lst <- list()
for (i in length(listOf_df)) {
    p <- ggplot(listOf_df[[i]]) + geom_line(aes(x=x, y=y))
    plotOutput_lst[[i]] <- p
}

#;; Somehow first entry is null, so only last one has a plot.
plotOutput_lst

#;; Only shows last plot, as first one is NULL
print(plotOutput_lst[[1]])
print(plotOutput_lst[[2]])


#;;-----------------------------------------------------------------------------
#;; With for loop, with force()
#;; Still, somehow first entry is null, so only last one has a plot.
plotOutput_lst <- list()
for (i in length(listOf_df)) {
    p <- ggplot(listOf_df[[i]]) + geom_line(aes(x=x, y=y))
    plotOutput_lst[[i]] <- force(p)
}

plotOutput_lst

print(plotOutput_lst[[1]])
print(plotOutput_lst[[2]])


#;;-----------------------------------------------------------------------------
#;; With map(), will work as expected:
rm(plotOutput_lst)
plotOutput_lst <- map(listOf_df, ~{
    p <- ggplot(.x) + geom_line(aes(x=x, y=y))
    p
})
plotOutput_lst

#;; This will print both plots
print(plotOutput_lst[[1]])
print(plotOutput_lst[[2]])