CODEWITHSUNDEEP
rfor-loopggplot2title
aegon
aegon

Reputation: 83

Changing title of plots in a loop with colnames() in R

I am creating a for loop which creates a ggplot2 plot for each of the first six columns in a dataframe. Everything works except for the looping of the title names. I have been trying to use title = colnames(df[,i]) and title = paste0(colnames(df[,i]) to create the proper title but it simply ends up repeating the 2nd column name. The plots themselves produce the data correctly for each column, but the title is for some reason not looping. For the first plot it produces the correct title, but then for the second plot and beyond it just keeps on repeating the third column name, completely skipping over the second column name. I even tried creating a variable within the loop to store the respective title name to then use within the ggplot2 title labels: changetitle <- colnames(df[,i]) and then using title = changetitle but that also loops incorrectly.

Here is an example of what I have so far:

plot_6 <- list()

for(i in df[1:6]){
   plot_6[i] <- print(ggplot(df, aes(x = i, ...) ...) +
             ... +
             labs(title = colnames(df[,i]),
                  x = ...) +
             ...)
}

Thank you very much.

Upvotes: 1

Views: 1962

Answers (1)

eipi10
eipi10

Reputation: 93811

df[1:6] is a data frame with six columns. When used as a loop variable, this results in i being a vector of values each time through the loop. This might "work" in the sense that ggplot will prroduce a plot, but it breaks the link between the data frame provided to ggplot (df in this case) and the mapping of df's columns to ggplot's aesthetics.

Here are a few options, using the built-in mtcars data frame:

library(tidyverse)
library(patchwork)

plot_6 <- list()

for(i in 1:6) {

  var = names(mtcars)[i]

  plot_6[[i]] <- ggplot(mtcars, aes(x = !!sym(var))) +
    geom_density() +
    labs(title = var)
}

# Use column names directly as loop variable
for(i in names(mtcars)[1:6]) {

  plot_6[[i]] <- ggplot(mtcars, aes(x = !!sym(i))) +
    geom_density() +
    labs(title = var)
}

# Use map, which directly generates a list of plots
plot_6 = map(names(mtcars)[1:6],
    ~ggplot(mtcars, aes(x = !!sym(.x))) +
      geom_density() +
      labs(title = .x)
)

Any of these produces the same list of plots:

wrap_plots(plot_6)

enter image description here

Upvotes: 2

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