PieChartAtomic: Atomic pie chart (internal)

In plotthis: High-Level Plotting Built Upon 'ggplot2' and Other Plotting Packages

Atomic pie chart (internal)

Description

Core implementation for drawing a single pie chart. This is the workhorse behind the exported PieChart function — it takes a single data frame (no split_by support) and returns a ggplot object. The chart maps the proportion of each x-axis category to the angle of a pie slice using coord_polar(), with optional faceting and per-slice labels.

Usage

PieChartAtomic(
  data,
  x,
  y = NULL,
  label = y,
  clockwise = TRUE,
  keep_na = FALSE,
  keep_empty = FALSE,
  theme = "theme_this",
  theme_args = list(),
  palette = "Paired",
  palcolor = NULL,
  palreverse = FALSE,
  alpha = 1,
  facet_by = NULL,
  facet_scales = "free_y",
  facet_ncol = NULL,
  facet_nrow = NULL,
  facet_byrow = TRUE,
  aspect.ratio = 1,
  legend.position = "right",
  legend.direction = "vertical",
  title = NULL,
  subtitle = NULL,
  xlab = NULL,
  ylab = NULL,
  ...
)

Arguments

data	A data frame.
x	A character string specifying the column name for the x-axis (categories). Must be character or factor. Each unique value becomes a pie slice.
y	A character string specifying the numeric column for the y-axis. When NULL (default), the count of observations in each (x, facet_by) combination is used and stored as .y.
label	A character string specifying the column to use for slice labels. NULL (default) hides labels. When TRUE, the y values are used as labels. When y = NULL, use ".y" to label with the computed counts.
clockwise	A logical value. When TRUE (default), the pie slices are ordered clockwise starting from the top. When FALSE, slices are ordered counter-clockwise.
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 x, group_by, fill_by, etc.
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 x, group_by, fill_by, etc. FALSE (default): Drop empty factor levels from the data before plotting. TRUE: Keep empty factor levels and show them as a separate category in the plot. "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: levels
theme	A character string or a theme class (i.e. ggplot2::theme_classic) specifying the theme to use. Default is "theme_this".
theme_args	A list of arguments to pass to the theme function.
palette	A character string specifying the palette to use. A named list or vector can be used to specify the palettes for different split_by values.
palcolor	A character string specifying the color to use in the palette. A named list can be used to specify the colors for different split_by values. If some values are missing, the values from the palette will be used (palcolor will be NULL for those values).
palreverse	A logical value indicating whether to reverse the palette. Default is FALSE.
alpha	A numeric value specifying the transparency of the plot.
facet_by	A character string specifying the column name of the data frame to facet the plot. Otherwise, the data will be split by split_by and generate multiple plots and combine them into one using patchwork::wrap_plots
facet_scales	Whether to scale the axes of facets. Default is "fixed" Other options are "free", "free_x", "free_y". See ggplot2::facet_wrap
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.
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.
facet_byrow	A logical value indicating whether to fill the plots by row. Default is TRUE.
aspect.ratio	A numeric value specifying the aspect ratio of the plot.
legend.position	A character string specifying the position of the legend. if waiver(), for single groups, the legend will be "none", otherwise "right".
legend.direction	A character string specifying the direction of the legend.
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.
subtitle	A character string specifying the subtitle of the plot.
xlab	A character string specifying the x-axis label.
ylab	A character string specifying the y-axis label.
...	Additional arguments.

Value

A ggplot object with height and width attributes (in inches) attached.

Architecture

1. ggplot dispatch — selects gglogger::ggplot or ggplot2::ggplot based on getOption("plotthis.gglogger.enabled").

2. Column resolution — x is forced to factor; y is validated (numeric, optional).

3. Count aggregation — when y = NULL, the count of observations per (x, facet_by) combination is computed as a new .y column. Factor levels are preserved after aggregation.

4. Label resolution — when label = TRUE, the label column is set to y. The label column is then validated.

5. Facet column resolution — facet_by columns are validated as factors, allowing up to two columns.

6. NA / empty-level handling — process_keep_na_empty() applies keep_na and keep_empty policies. Per-column keep_empty settings are extracted for x and facet_by. When more than one facet column is provided, their keep_empty values must be identical.

7. Clockwise ordering — when clockwise = TRUE (default), the levels of x are reversed so that the first slice starts from the top and proceeds clockwise. The data is then sorted by the (possibly reversed) x factor levels.

8. Position calculation — if faceted, grouping by facet variables; computes cumulative sums (csum) and label midpoint positions (pos) for each slice.

9. Colour mapping — palette_this() assigns colours to all x levels, including NA (defaulting to "grey80").

10. Plot assembly — the ggplot object is built with geom_col(width = 1) and coord_polar(theta = "y") to create the circular pie layout. The fill scale uses scale_fill_manual() with per-slice colours; the drop argument is controlled by keep_empty_x.

11. Labels — when label is not NULL, geom_label_repel() adds text labels at the computed midpoint positions (pos).

12. Dimension calculation — calculate_plot_dimensions() computes plot height and width from aspect.ratio and legend metrics. The resulting height / width attributes are stored on the ggplot object.

13. Faceting — facet_plot() wraps the plot with facet_wrap / facet_grid if facet_by is provided, respecting the keep_empty setting for facet variables.

plotthis documentation built on July 9, 2026, 5:07 p.m.