Pictogram grid layout

stat_pictogram() turns one row of data (an anchor position and a value) into one row per icon slot in a grid, ready for geom_pictogram() to draw. It's the counting/layout half of a pictogram.

Usage

stat_pictogram(
  mapping = NULL,
  data = NULL,
  geom = "pictogram",
  position = "identity",
  ...,
  n = NULL,
  nrow = NULL,
  ncol = NULL,
  symbol_value = NULL,
  n_target = 20,
  flow = "row",
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping

Set of aesthetic mappings created by aes(). If specified and inherit.aes = TRUE (the default), it is combined with the default mapping at the top level of the plot. You must supply mapping if there is no plot mapping.

data

The data to be displayed in this layer. There are three options:

If NULL, the default, the data is inherited from the plot data as specified in the call to ggplot().

A data.frame, or other object, will override the plot data. All objects will be fortified to produce a data frame. See fortify() for which variables will be created.

A function will be called with a single argument, the plot data. The return value must be a data.frame, and will be used as the layer data. A function can be created from a formula (e.g. ~ head(.x, 10)).

geom

Override the default connection between stat_pictogram() and geom_pictogram(). For more information about overriding these connections, see ggplot2::layer().

position

A position adjustment to use on the data for this layer. This can be used in various ways, including to prevent overplotting and improving the display. The position argument accepts the following:

The result of calling a position function, such as position_jitter(). This method allows for passing extra arguments to the position.
A string naming the position adjustment. To give the position as a string, strip the function name of the position_ prefix. For example, to use position_jitter(), give the position as "jitter".
For more information and other ways to specify the position, see the layer position documentation.

...

Other arguments passed on to layer()'s params argument. These arguments broadly fall into one of 4 categories below. Notably, further arguments to the position argument, or aesthetics that are required can not be passed through .... Unknown arguments that are not part of the 4 categories below are ignored.

Static aesthetics that are not mapped to a scale, but are at a fixed value and apply to the layer as a whole. For example, colour = "red" or linewidth = 3. The geom's documentation has an Aesthetics section that lists the available options. The 'required' aesthetics cannot be passed on to the params. Please note that while passing unmapped aesthetics as vectors is technically possible, the order and required length is not guaranteed to be parallel to the input data.
When constructing a layer using a stat_*() function, the ... argument can be used to pass on parameters to the geom part of the layer. An example of this is stat_density(geom = "area", outline.type = "both"). The geom's documentation lists which parameters it can accept.
Inversely, when constructing a layer using a geom_*() function, the ... argument can be used to pass on parameters to the stat part of the layer. An example of this is geom_area(stat = "density", adjust = 0.5). The stat's documentation lists which parameters it can accept.
The key_glyph argument of layer() may also be passed on through .... This can be one of the functions described as key glyphs, to change the display of the layer in the legend.

n

Total slots in the grid (fixed-grid mode). NULL (the default) grows the grid to fit value instead.

nrow, ncol

Grid shape. Set at most one; the other is derived to wrap the slots. Both NULL wraps to a single row/column; see Orientation for which.

symbol_value

The data value one slot represents. NULL (the default) picks one automatically: 1 in fixed-grid mode (value is already a slot count, e.g. a percentage out of n = 100), or, in growing mode, the smallest "nice" round number (1, 2 or 5 times a power of ten) that keeps the layer's largest value to around n_target icons; see that argument. Set explicitly to turn auto-picking off.

n_target

In growing mode, roughly how many icons deep the growing dimension should get for the layer's largest value, when symbol_value is picked automatically. Turn this up for a finer-grained chart (more, smaller icons), down for a coarser one (fewer, bigger icons). Ignored if symbol_value is set explicitly, or in fixed-grid mode.

flow

Fill order: "row" (default) fills left-to-right then wraps to the next row; "col" fills top-to-bottom then wraps to the next column.

na.rm

If FALSE, the default, missing values are removed with a warning. If TRUE, missing values are silently removed.

show.legend

logical. Should this layer be included in the legends? NA, the default, includes if any aesthetics are mapped. FALSE never includes, and TRUE always includes. It can also be a named logical vector to finely select the aesthetics to display. To include legend keys for all levels, even when no data exists, use TRUE. If NA, all levels are shown in legend, but unobserved levels are omitted.

inherit.aes

If FALSE, overrides the default aesthetics, rather than combining with them. This is most useful for helper functions that define both data and aesthetics and shouldn't inherit behaviour from the default plot specification, e.g. annotation_borders().

Value

A ggplot2 layer.

Grid sizing

Two modes, chosen by whether n (or both nrow and ncol) is set:

Fixed grid (n, or both nrow/ncol, given): the grid always has n slots; round(value / symbol_value) of them are filled (capped at n), the rest empty. This is the waffle-chart/rating-widget shape: proportions vary, the grid footprint doesn't.
Growing grid (n, nrow and ncol all left NULL, or only one of nrow/ncol given): the grid has exactly round(value / symbol_value) slots, all filled. An isotype/unit-chart shape where more icons is the value, so the footprint grows with it.

At most one of nrow/ncol needs setting; the other wraps to fit. With neither set, the grid defaults to a single row, unless x/y asks for a bar/column shape instead; see Orientation below.

Orientation

x and y are the grid's anchor, but only value is actually required. Map both and you get a fixed-position grid, centred on (x, y): a waffle chart or rating widget. Leave one unmapped and that becomes the growth axis of a bar-style stack instead, anchored to that edge of the plot panel. aes(x = category, value = count) draws a column chart, one growing column per category, up from the bottom of the panel; aes(y = category, value = count) draws a horizontal bar, growing right from the left of the panel.

Examples