epi_plot_bar: Barplot wrapper function using ggplot2

In AntonioJBT/episcout: Quickly Clean, Explore and Visualise Large Epidemiological Datasets

Barplot wrapper function using ggplot2

Description

epi_plot_bar() wraps ggplot2 barplot for one or two variables with a number of set preferences, see below.

Usage

epi_plot_bar(
  df = NULL,
  var_x = NULL,
  var_y = "",
  fill = NULL,
  bar_colour = "black",
  guides_fill = "none",
  y_lab = "Count",
  x_lab = var_x,
  custom_palette = NULL,
  ...
)

Arguments

df	data.frame with x var to plot
var_x	Variable to plot on x-axis, pass as a string.
var_y	Variable to plot on y-axis, pass as a string.
fill	Interior colour used to fill. If only passing var_x it defaults to 'black'. If passing both var_y and var_x, it uses var_x.
bar_colour	Aesthetics for ggplot2. Default is 'black' if only var_x.
guides_fill	Fill for ggplot2 guides. Default is 'none'.
y_lab	y-axis label. Default is 'Count'.
x_lab	x-axis label. Default is x_var.
custom_palette	Optional vector of fill colours to override the default palette. If provided, colours are recycled to match the number of levels.
...	pass further arguments to ggplot2::geom_bar()

Value

Prints a ggplot2 barplot

Note

For other options, save as object and build on the layers. var_x and var_y are passed to ggplot2::aes_string. For colour and fill see ggplot2::fill for further information. epi_plot_bar() for one variable uses stat = 'count' and is coloured according to the x variable passed, black borders for bars and no legend by default. For two variables it assumes you want to colour according to the x variable and that stat = 'identity' is what's needed. No legend by default. stat = 'identity' uses the height of the bar to represent the value of the passed column.

Author(s)

Antonio Berlanga-Taylor <\url{https://github.com/AntonioJBT/episcout}>

See Also

epi_plot_list, epi_plots_to_grid, epi_plot_box, epi_plot_hist, ggplot, geom_bar.

Examples

## Not run: 
# Set up an example:
set.seed(12345)
n <- 20
df <- data.frame(
  var_id = rep(1:(n / 2), each = 2),
  var_to_rep = rep(c("Pre", "Post"), n / 2),
  x = rnorm(n),
  y = rbinom(n, 1, 0.50),
  z = rpois(n, 2),
  w = sample(1:20, 20)
)
df$id_unique <- paste0(df[["var_id"]], "_", df[["var_to_rep"]])
df[, "var_id"] <- as.character(df[, "var_id"])
df[, "y"] <- as.factor(df[, "y"])
str(df)

# Barplot for single variable:
summary(df$var_to_rep)
plot_bar <- epi_plot_bar(df, "var_to_rep")
plot_bar

# Barplot for two variables side by side:
df_bar <- reshape2::melt(df[, c("w", "z", "id_unique")], id.vars = "id_unique")
epi_head_and_tail(df, cols = 7)
epi_head_and_tail(df_bar, cols = 3)
plot_bar <- epi_plot_bar(df_bar,
  var_x = "id_unique",
  var_y = "value",
  fill = "variable"
) +
  theme(axis.text.x = element_text(angle = 90, hjust = 1))
plot_bar
# Which should be the same as:
ggplot(df_bar, aes(x = id_unique, y = value, fill = variable)) +
  geom_bar(stat = "identity", position = "dodge") +
  theme(axis.text.x = element_text(angle = 90, hjust = 1))

## End(Not run)

AntonioJBT/episcout documentation built on June 11, 2025, 7:26 p.m.