% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/barplot.R
\name{BarPlot}
\alias{BarPlot}
\alias{SplitBarPlot}
\alias{WaterfallPlot}
\title{Bar / SplitBar / Waterfall Plot}
\usage{
BarPlot(
  data,
  x,
  x_sep = "_",
  y = NULL,
  flip = FALSE,
  fill_by = TRUE,
  fill_name = NULL,
  line_name = NULL,
  label_nudge = 0.02,
  label = NULL,
  label_fg = "black",
  label_size = 4,
  label_bg = "white",
  label_bg_r = 0.1,
  group_by = NULL,
  group_by_sep = "_",
  group_name = NULL,
  split_by = NULL,
  split_by_sep = "_",
  facet_by = NULL,
  facet_scales = "fixed",
  facet_ncol = NULL,
  facet_nrow = NULL,
  facet_byrow = TRUE,
  facet_args = list(),
  add_bg = FALSE,
  bg_palette = "stripe",
  bg_palcolor = NULL,
  bg_alpha = 0.2,
  add_line = NULL,
  line_color = "red2",
  line_width = 0.6,
  line_type = 2,
  add_trend = FALSE,
  trend_color = "black",
  trend_linewidth = 1,
  trend_ptsize = 2,
  theme = "theme_this",
  theme_args = list(),
  palette = NULL,
  palcolor = NULL,
  palreverse = FALSE,
  alpha = 1,
  lower_quantile = 0,
  upper_quantile = 0.99,
  lower_cutoff = NULL,
  upper_cutoff = NULL,
  x_text_angle = 0,
  aspect.ratio = 1,
  y_min = NULL,
  y_max = NULL,
  position = "auto",
  position_dodge_preserve = "total",
  legend.position = "right",
  legend.direction = "vertical",
  title = NULL,
  subtitle = NULL,
  xlab = NULL,
  ylab = NULL,
  keep_empty = FALSE,
  keep_na = FALSE,
  expand = waiver(),
  width = waiver(),
  combine = TRUE,
  nrow = NULL,
  ncol = NULL,
  byrow = TRUE,
  seed = 8525,
  axes = NULL,
  axis_titles = axes,
  guides = NULL,
  design = NULL,
  ...
)

SplitBarPlot(
  data,
  x,
  y,
  y_sep = "_",
  flip = FALSE,
  split_by = NULL,
  split_by_sep = "_",
  alpha_by = NULL,
  alpha_reverse = FALSE,
  alpha_name = NULL,
  order_y = list(`+` = c("x_desc", "alpha_desc"), `-` = c("x_desc", "alpha_asc")),
  bar_height = 0.9,
  lineheight = 0.5,
  max_charwidth = 80,
  fill_by = NULL,
  fill_by_sep = "_",
  fill_name = NULL,
  direction_name = "direction",
  direction_pos_name = "positive",
  direction_neg_name = "negative",
  theme = "theme_this",
  theme_args = list(),
  palette = "Spectral",
  palcolor = NULL,
  palreverse = FALSE,
  lower_quantile = 0,
  upper_quantile = 0.99,
  lower_cutoff = NULL,
  upper_cutoff = NULL,
  facet_by = NULL,
  facet_scales = "free_y",
  facet_nrow = NULL,
  facet_ncol = NULL,
  facet_byrow = TRUE,
  aspect.ratio = 1,
  x_min = NULL,
  x_max = NULL,
  legend.position = "right",
  legend.direction = "vertical",
  title = NULL,
  subtitle = NULL,
  xlab = NULL,
  ylab = NULL,
  keep_empty = FALSE,
  keep_na = FALSE,
  combine = TRUE,
  nrow = NULL,
  ncol = NULL,
  byrow = TRUE,
  seed = 8525,
  axes = NULL,
  axis_titles = axes,
  guides = NULL,
  design = NULL,
  ...
)

WaterfallPlot(
  data,
  x,
  y,
  y_sep = "_",
  flip = FALSE,
  split_by = NULL,
  split_by_sep = "_",
  alpha_by = NULL,
  alpha_reverse = FALSE,
  alpha_name = NULL,
  order_y = list(`+` = c("x_desc", "alpha_desc"), `-` = c("x_desc", "alpha_asc")),
  bar_height = 0.9,
  lineheight = 0.5,
  max_charwidth = 80,
  fill_by = NULL,
  fill_by_sep = "_",
  fill_name = NULL,
  direction_name = "direction",
  direction_pos_name = "positive",
  direction_neg_name = "negative",
  theme = "theme_this",
  theme_args = list(),
  palette = "Spectral",
  palcolor = NULL,
  palreverse = FALSE,
  lower_quantile = 0,
  upper_quantile = 0.99,
  lower_cutoff = NULL,
  upper_cutoff = NULL,
  facet_by = NULL,
  facet_scales = "free_y",
  facet_nrow = NULL,
  facet_ncol = NULL,
  facet_byrow = TRUE,
  aspect.ratio = 1,
  x_min = NULL,
  x_max = NULL,
  legend.position = "right",
  legend.direction = "vertical",
  title = NULL,
  subtitle = NULL,
  xlab = NULL,
  ylab = NULL,
  keep_empty = FALSE,
  keep_na = FALSE,
  combine = TRUE,
  nrow = NULL,
  ncol = NULL,
  byrow = TRUE,
  seed = 8525,
  axes = NULL,
  axis_titles = axes,
  guides = NULL,
  design = NULL,
  ...
)
}
\arguments{
\item{data}{A data frame.}

\item{x}{A character string specifying the column name of the data frame to plot for the x-axis.}

\item{x_sep}{A character string to join multiple \code{x} columns.
Default \code{"_"}.}

\item{y}{A character string specifying the column name of the data frame to plot for the y-axis.}

\item{flip}{Logical; if \code{TRUE}, swap the x and y axes.}

\item{fill_by}{A variable used to fill the bars.  Both categorical and
numeric columns are accepted:
\itemize{
\item \code{TRUE} (default) — fill by the x-axis values.
\item \code{FALSE} — solid fill (first palette colour).
\item A column name (character/factor) — discrete colour scale.
\item A column name (numeric) — continuous gradient with quantile
/ cutoff controls.
}
Ignored when \code{group_by} is provided (fill is determined by
\code{group_by}).}

\item{fill_name}{A character string for the fill legend title.  Only
applies when \code{group_by = NULL} and the fill is from \code{fill_by}.}

\item{line_name}{Legend name for the reference line.}

\item{label_nudge}{A numeric value controlling the distance between labels
and the bar top, expressed as a fraction of the data range.}

\item{label}{A column name (or \code{TRUE}) for text labels on bars.
When \code{TRUE}, the y-axis values are labelled.  When a column name,
the values in that column are used.}

\item{label_fg}{A character string specifying the label text colour.}

\item{label_size}{A numeric value specifying the label text size.}

\item{label_bg}{A character string specifying the label background colour.}

\item{label_bg_r}{A numeric value specifying the label background corner
radius.}

\item{group_by}{Columns to group the data for plotting
For those plotting functions that do not support multiple groups,
They will be concatenated into one column, using \code{group_by_sep} as the separator}

\item{group_by_sep}{The separator for multiple group_by columns. See \code{group_by}}

\item{group_name}{A character string for the group fill legend title.
When \code{NULL}, the \code{group_by} column name is used.}

\item{split_by}{The column(s) to split the data by for separate sub-plots.}

\item{split_by_sep}{Separator for concatenated \code{split_by} columns.}

\item{facet_by}{A character string specifying the column name of the data frame to facet the plot.
Otherwise, the data will be split by \code{split_by} and generate multiple plots
and combine them into one using \code{patchwork::wrap_plots}}

\item{facet_scales}{Whether to scale the axes of facets. Default is "fixed"
Other options are "free", "free_x", "free_y". See \code{ggplot2::facet_wrap}}

\item{facet_ncol}{A numeric value specifying the number of columns in the facet.
When facet_by is a single column and facet_wrap is used.}

\item{facet_nrow}{A numeric value specifying the number of rows in the facet.
When facet_by is a single column and facet_wrap is used.}

\item{facet_byrow}{A logical value indicating whether to fill the plots by row. Default is TRUE.}

\item{facet_args}{A list of additional arguments passed to the faceting
function (e.g., \code{scales}, \code{labeller}).}

\item{add_bg}{Logical; add alternating background stripes behind the bars.}

\item{bg_palette}{Palette for the background stripes.}

\item{bg_palcolor}{Custom colours for the background stripes.}

\item{bg_alpha}{Alpha transparency for the background stripes.}

\item{add_line}{A numeric y-intercept for a horizontal reference line.}

\item{line_color}{Colour of the reference line.}

\item{line_width}{Width of the reference line.}

\item{line_type}{Linetype of the reference line (e.g., 1 = solid, 2 = dashed).}

\item{add_trend}{Logical; add a trend line and points connecting the bar tops.}

\item{trend_color}{Colour of the trend line.}

\item{trend_linewidth}{Width of the trend line.}

\item{trend_ptsize}{Size of the trend line points.}

\item{theme}{A character string or a theme class (i.e. ggplot2::theme_classic) specifying the theme to use.
Default is "theme_this".}

\item{theme_args}{A list of arguments to pass to the theme function.}

\item{palette}{A character string specifying the palette to use.
A named list or vector can be used to specify the palettes for different \code{split_by} values.}

\item{palcolor}{A character string specifying the color to use in the palette.
A named list can be used to specify the colors for different \code{split_by} values.
If some values are missing, the values from the palette will be used (palcolor will be NULL for those values).}

\item{palreverse}{A logical value indicating whether to reverse the palette. Default is FALSE.}

\item{alpha}{A numeric value specifying the transparency of the plot.}

\item{lower_quantile, upper_quantile}{Lower and upper quantiles for the continuous color/fill scale.
The actual cutoffs are determined by these quantiles when \code{lower_cutoff} and
\code{upper_cutoff} are \code{NULL}. Defaults: \code{lower_quantile = 0}, \code{upper_quantile = 0.99}.}

\item{lower_cutoff, upper_cutoff}{Explicit lower and upper cutoffs for the continuous color/fill scale.
When \code{NULL} (the default), the cutoffs are determined by \code{lower_quantile} and
\code{upper_quantile} via \code{\link[stats]{quantile}}. Values outside the
\code{[lower_cutoff, upper_cutoff]} range are clamped (winsorized) to the nearest cutoff value.}

\item{x_text_angle}{A numeric value specifying the angle of the x-axis text.}

\item{aspect.ratio}{A numeric value specifying the aspect ratio of the plot.}

\item{y_min, y_max}{Numeric limits for the y-axis (or x-axis when flipped).}

\item{position}{A character string specifying the bar layout:
\code{"auto"} (default: dodge when \eqn{\le}5 groups, stack otherwise),
\code{"dodge"} (side-by-side), or \code{"stack"} (stacked on top of
each other).}

\item{position_dodge_preserve}{A character string passed to
\code{\link[ggplot2]{position_dodge2}()}: \code{"total"} preserves the
overall bar group width; \code{"single"} preserves individual bar widths.}

\item{legend.position}{A character string specifying the position of the legend.
if \code{waiver()}, for single groups, the legend will be "none", otherwise "right".}

\item{legend.direction}{A character string specifying the direction of the legend.}

\item{title}{A character string specifying the title of the plot.
A function can be used to generate the title based on the default title.
This is useful when split_by is used and the title needs to be dynamic.}

\item{subtitle}{A character string specifying the subtitle of the plot.}

\item{xlab}{A character string specifying the x-axis label.}

\item{ylab}{A character string specifying the y-axis label.}

\item{keep_empty}{One of FALSE, TRUE and "level". It can also take a named list to specify
different behavior for different columns. Without a named list, the behavior applies to the
categorical/character columns used on the plot, for example, the \code{x}, \code{group_by}, \code{fill_by}, etc.
\itemize{
\item{\code{FALSE} (default): Drop empty factor levels from the data before plotting.}
\item{\code{TRUE}: Keep empty factor levels and show them as a separate category in the plot.}
\item{\code{"level"}: Keep empty factor levels, but do not show them in the plot.
But they will be assigned colors from the palette to maintain consistency across multiple plots.
Alias: \code{levels}}
}}

\item{keep_na}{A logical value or a character to replace the NA values in the data.
It can also take a named list to specify different behavior for different columns.
If TRUE or NA, NA values will be replaced with NA.
If FALSE, NA values will be removed from the data before plotting.
If a character string is provided, NA values will be replaced with the provided string.
If a named vector/list is provided, the names should be the column names to apply the behavior to,
and the values should be one of TRUE, FALSE, or a character string.
Without a named vector/list, the behavior applies to categorical/character columns used on the plot,
for example, the \code{x}, \code{group_by}, \code{fill_by}, etc.}

\item{expand}{The values to expand the x and y axes. It is like CSS padding.
When a single value is provided, it is used for both axes on both sides.
When two values are provided, the first value is used for the top/bottom side and the second value is used for the left/right side.
When three values are provided, the first value is used for the top side, the second value is used for the left/right side, and the third value is used for the bottom side.
When four values are provided, the values are used for the top, right, bottom, and left sides, respectively.
You can also use a named vector to specify the values for each side.
When the axis is discrete, the values will be applied as 'add' to the 'expansion' function.
When the axis is continuous, the values will be applied as 'mult' to the 'expansion' function.
See also \url{https://ggplot2.tidyverse.org/reference/expansion.html}}

\item{width}{A numeric value specifying the bar width (0–1).}

\item{combine}{Logical; when \code{TRUE} (default), returns a combined
\code{patchwork} object.  When \code{FALSE}, returns a named list of
\code{ggplot} objects.}

\item{ncol, nrow}{Integer number of columns / rows for the combined layout.}

\item{byrow}{Logical; fill the combined layout by row (default \code{TRUE}).}

\item{seed}{A numeric seed for reproducibility.}

\item{axes, axis_titles}{Character strings for axis handling in the
combined layout.}

\item{guides}{Character string for legend collection across panels.}

\item{design}{A custom layout design for the combined plot.}

\item{...}{Additional arguments.}

\item{y_sep}{A character string to join multiple \code{y} columns.
Default \code{"_"}.}

\item{alpha_by}{A character string naming a numeric column to encode as
bar opacity.  Default \code{NULL} (all bars fully opaque).}

\item{alpha_reverse}{Logical; if \code{TRUE}, reverse the alpha scale
direction (solid for low values, transparent for high).}

\item{alpha_name}{A character string for the alpha legend title.}

\item{order_y}{A named list controlling the vertical ordering of bars.
Keys are \code{"+"} (positive bars), \code{"-"} (negative bars), or
\code{"*"} (all bars).  Values are character vectors of ordering
criteria: \code{"x_asc"}, \code{"x_desc"}, \code{"alpha_asc"},
\code{"alpha_desc"}.  Default orders positive bars by descending x and
descending alpha; negative bars by descending x and ascending alpha.}

\item{bar_height}{A numeric value (0–1) specifying the bar height as a
fraction of the available category slot.}

\item{lineheight}{A numeric value controlling the line height of wrapped
category labels.}

\item{max_charwidth}{An integer specifying the maximum character width
for wrapping category labels.}

\item{fill_by_sep}{A character string to join multiple \code{fill_by}
columns.  Default \code{"_"}.}

\item{direction_name}{A character string naming the internal direction
column (used in legends).  Default \code{"direction"}.}

\item{direction_pos_name}{A character string labelling the positive
direction in the legend.  Default \code{"positive"}.}

\item{direction_neg_name}{A character string labelling the negative
direction in the legend.  Default \code{"negative"}.}

\item{x_min, x_max}{Numeric limits for the x-axis.  When \code{NULL},
symmetric limits are computed from the maximum absolute x-value.}
}
\value{
A \code{ggplot} object, a \code{patchwork} object, or a named list
of \code{ggplot} objects (when \code{combine = FALSE}), each with
\code{height} and \code{width} attributes in inches.

A \code{ggplot} object, a \code{patchwork} object, or a named list
of \code{ggplot} objects (when \code{combine = FALSE}), each with
\code{height} and \code{width} attributes in inches.
}
\description{
\code{BarPlot} draws bar plots with flexible fill, grouping, labelling, and annotation
options.  Supports both simple single-colour bars and grouped bars (dodged
or stacked).  Bars can be filled by a categorical variable (discrete
colour scale), a continuous variable (colour gradient), or a fixed colour.

The function supports \strong{count aggregation} (omit \code{y} to plot
observation counts), \strong{proportion scaling} (\code{scale_y = TRUE}
for grouped bars), background stripes (\code{add_bg}), bar labels, trend
lines, horizontal reference lines, and splitting into separate sub-plots
via \code{split_by}.

\code{SplitBarPlot} (also known as \code{WaterfallPlot}) draws a divergent bar plot
where bars extend left (negative values) and right (positive values) from a
central zero line.  The bar fill colour and opacity can encode additional
variables, and the vertical ordering of categories is fully customisable.

The function supports \strong{split_by} to produce separate panels,
\strong{facet_by} for grouped views within panels, and
\strong{alpha_by} for encoding a secondary numeric variable via opacity.
}
\section{split_by workflow}{

When \code{split_by} is provided:
\enumerate{
\item \code{\link{check_keep_na}()} and \code{\link{check_keep_empty}()}
normalise the \code{keep_na} / \code{keep_empty} arguments for all
columns (\code{x}, \code{split_by}, \code{facet_by}, \code{group_by}).
\item The \code{split_by} column is validated and its NA / empty levels
are processed.  It is then removed from the per-column
\code{keep_na} / \code{keep_empty} lists.
\item The data is split by \code{split_by} (preserving level order).  If
\code{split_by} is \code{NULL}, the data is wrapped in a
single-element list with name \code{"..."}.
\item Per-split \code{palette}, \code{palcolor},
\code{legend.position}, and \code{legend.direction} are resolved
via \code{\link{check_palette}()}, \code{\link{check_palcolor}()},
and \code{\link{check_legend}()}.
\item \code{\link{BarPlotAtomic}()} is called for each split.
\item Results are combined via \code{\link{combine_plots}()} (when
\code{combine = TRUE}) or returned as a named list.
}


When \code{split_by} is provided:
\enumerate{
\item \code{\link{check_keep_na}()} and \code{\link{check_keep_empty}()}
normalise the \code{keep_na} / \code{keep_empty} arguments.
\item The \code{split_by} column is validated and its NA / empty levels
are processed.  It is then removed from the per-column lists.
\item The data is split by \code{split_by} (preserving level order).
\item Per-split \code{palette}, \code{palcolor},
\code{legend.position}, and \code{legend.direction} are resolved.
\item \code{\link{SplitBarPlotAtomic}()} is called for each split.
When \code{title} is a function, it receives the split level name
for dynamic title generation.
\item Results are combined via \code{\link{combine_plots}()}.
}
}

\examples{
\donttest{
data <- data.frame(
    x = c("A", "B", "C", "D", "E", "F", "G", "H"),
    y = c(10, 8, 16, 4, 6, 12, 14, 2),
    group = c("G1", "G1", "G2", "G2", "G3", "G3", "G4", "G4"),
    facet = c("F1", "F2", "F3", "F4", "F1", "F2", "F3", "F4")
)

# Single-colour bars
BarPlot(data, x = "x", y = "y")

# Solid fill (no colour mapping)
BarPlot(data, x = "x", y = "y", fill_by = FALSE)

# Label bar tops
BarPlot(data, x = "x", y = "y", label = TRUE)
BarPlot(data, x = "x", y = "y", label = "facet", label_nudge = 0)

# Grouped bars
BarPlot(data, x = "group", y = "y", group_by = "x")

# Dodged bars with background stripes
BarPlot(data,
    x = "group", y = "y", group_by = "x",
    position = "dodge", add_bg = TRUE)

# split_by with faceting
BarPlot(data,
    x = "x", y = "y", split_by = "group",
    facet_by = "facet", position = "dodge", facet_ncol = 1)

# split_by with collected guides
BarPlot(data,
    x = "x", y = "y", split_by = "group", facet_by = "facet",
    position = "dodge", facet_ncol = 1, guides = 'collect')

# Per-split palettes
BarPlot(data,
    x = "x", y = "y", split_by = "group",
    palette = list(G1 = "Reds", G2 = "Blues", G3 = "Greens", G4 = "Purp"),
    facet_by = "facet", position = "dodge", facet_ncol = 1)

# Background stripe palette
BarPlot(data,
    x = "group", y = "y", group_by = "x",
    position = "dodge", add_bg = TRUE, bg_palette = "Spectral")

# Count bars (y = NULL)
BarPlot(data, x = "group", ylab = "count")

# Flipped axes
BarPlot(data, x = "group", flip = TRUE, ylab = "count")

# Numeric fill_by with colour gradient
BarPlot(data, x = "x", y = "y", fill_by = "y", flip = TRUE)

# Control fill colour scale limits (quantile)
BarPlot(data, x = "x", y = "y", fill_by = "y", flip = TRUE,
        lower_quantile = 0.1, upper_quantile = 0.9)

# Control fill colour scale limits (explicit cutoff)
BarPlot(data, x = "x", y = "y", fill_by = "y", flip = TRUE,
        lower_cutoff = 5, upper_cutoff = 12)

# keep_na and keep_empty examples
data <- data.frame(
    x = factor(c("A", "B", "C", "D", "E", "F", NA, "H"),
               levels = LETTERS[1:10]),
    y = c(10, 8, 16, 4, 6, NA, 14, 2),
    group = factor(c("G1", "G1", "G2", NA, "G3", "G3", "G5", "G5"),
                   levels = c("G1", "G2", "G3", "G4", "G5")),
    facet = factor(c("F1", NA, "F3", "F4", "F1", "F2", "F3", "F4"),
                   levels = c("F1", "F2", "F3", "F4", "F5"))
)

# Default: NA and empty levels dropped
BarPlot(data, x = "x", y = "y")

# Keep both NA and empty levels
BarPlot(data, x = "x", y = "y",
        keep_na = TRUE, keep_empty = TRUE)

# With faceting
BarPlot(data, x = "x", y = "y",
        keep_na = TRUE, keep_empty = TRUE, facet_by = "facet")

# Keep NA, hide empty levels but reserve their colours
BarPlot(data, x = "x", y = "y",
        keep_na = TRUE, keep_empty = 'level')

# Per-column keep_na / keep_empty
BarPlot(data, x = "x", y = "y",
        keep_na = list(x = TRUE), keep_empty = list(x = FALSE))

# Grouped bars with keep_na / keep_empty
BarPlot(data, x = "group", y = "y", group_by = "x")
BarPlot(data, x = "group", y = "y", group_by = "x",
        keep_na = TRUE, keep_empty = TRUE)
BarPlot(data, x = "group", y = "y", group_by = "x",
        keep_na = TRUE, keep_empty = TRUE, facet_by = "facet")

# Per-column on grouped bars
BarPlot(data, x = "group", y = "y", group_by = "x",
        keep_na = list(x = TRUE, group = FALSE),
        keep_empty = list(x = FALSE, group = TRUE))
}
\donttest{
set.seed(8525)
data <- data.frame(
    word = c("apple", "banana", "cherry", "date", "elderberry",
             "It is a very long term with a lot of words"),
    count = c(-10, 20, -30, 40, 50, 34),
    score = c(1, 2, 3, 4, 5, 3.2),
    group = c("A", "A", "B", "B", "C", "C")
)

# Basic split bar plot with alpha encoding
SplitBarPlot(data, x = "count", y = "word", alpha_by = "score")

# Control label wrapping
SplitBarPlot(data, x = "count", y = "word", alpha_by = "score",
             max_charwidth = 30, lineheight = 1.1)

# Fill by categorical variable
SplitBarPlot(data, x = "count", y = "word", fill_by = "group")

# Faceting
SplitBarPlot(data, x = "count", y = "word", facet_by = "group",
             fill_name = "Direction")

# Per-split palettes
SplitBarPlot(data, x = "count", y = "word", alpha_by = "score",
             split_by = "group",
             palette = c(A = "Reds", B = "Blues", C = "Greens"))

# keep_na and keep_empty examples
data <- data.frame(
    word = factor(c("apple", "banana", "cherry", NA, "elderberry",
         "It is a very long term with a lot of words"),
         levels = c("apple", "banana", "cherry", "date", "elderberry",
             "unused", "It is a very long term with a lot of words")),
    count = c(-10, 20, NA, 40, 10, 34),
    score = c(1, 2, 3, 4, 5, 3.2),
    group = factor(sample(c("A", "A", "B", "B", "C", "C")),
         levels = c("A", "B", "C", "D"))
)

# Default: NA and empty levels dropped
SplitBarPlot(data, x = "count", y = "word", alpha_by = "score")

# Keep NA and empty levels
SplitBarPlot(data, x = "count", y = "word", alpha_by = "score",
             keep_na = TRUE, keep_empty = TRUE)

# Keep with faceting
SplitBarPlot(data, x = "count", y = "word", alpha_by = "score",
             keep_na = TRUE, keep_empty = TRUE, facet_by = "group")

# Keep NA, hide empty levels (reserve colours)
SplitBarPlot(data, x = "count", y = "word", alpha_by = "score",
             keep_na = TRUE, keep_empty = "level")

# Per-column control
SplitBarPlot(data, x = "count", y = "word", alpha_by = "score",
             keep_na = list(word = FALSE), keep_empty = list(word = TRUE))

# Control fill colour scale limits
SplitBarPlot(data, x = "count", y = "word", fill_by = "score",
             lower_cutoff = 1, upper_cutoff = 4)
}
}
