Plotting function doesn't grab names during lapply

Question

I'm trying to allow lapply to access the names of the list of plots that I'm feeding it. I have looked at a few other posts that seem very similar but still not sure how to pass it the vector of names of my list.

require(mlbench)
require(gridExtra)
require(dplyr)
require(ggplot2)

data(Soybean)

dfs <- lapply(Soybean, function(x) data.frame(table(x, exclude = NULL)))

display_charts <- function(x){
  ggplot(data.frame(x) %>% select(x = 1, y = 2), aes(x = x, y = y)) + 
    geom_col(col = 'red',
             fill = 'green',
             alpha = 0.3) +
    labs(title = names(x),
         x = names(x),
         y = 'Frequency')
}

all_charts <- lapply(dfs, display_charts)

n <- length(all_charts)
nCol <- floor(sqrt(n))
do.call("grid.arrange", c(all_charts, ncol=nCol))

I have tried to adjust the lapply function by adjusting the display_charts function to accept a name argument, and replacing names(x) with name, and then creating a vector of names called nms <- names(dfs), and then doing seq_along(dfs), display_charts, x = dfs, nm = nms but it doesn't work.

This plot produces a 6x6 grid of frequency plots for the dataset, but I would like to have the title be each name of the plot. I feel like this is looking me square in the face, and I can't see it.

pogibas pogibas · Accepted Answer · 2018-01-27T19:59:48

Instead of using lapply to iterate over list of dfs iterate over the length if it with:

# Replaced `all_charts <- lapply(dfs, display_charts)` with:
all_charts <- lapply(seq_along(dfs), function(i) display_charts(dfs[i]))

And for ggplot input in display_charts() function use x[[1]] as it's still a list:

display_charts <- function(x) {
  library(ggplot2)
  ggplot(x[[1]] %>% select(x = 1, y = 2), aes(x = x, y = y)) + 
    geom_col(col = 'red',
             fill = 'green',
             alpha = 0.3) +
    labs(title = names(x),
         x = names(x),
         y = 'Frequency')
}

Plotting function doesn't grab names during lapply

1 Answers