Bar

Layers are declared with the DRAW clause. Read the documentation for this clause for a thorough description of how to use it.

The bar layer is used to create bar plots. You can either specify the height of the bars directly or let the layer calculate it either as the count of records within the same group or as a weighted sum of the records.

Aesthetics

The following aesthetics are recognised by the bar layer.

Required

The bar layer has no required aesthetics

Optional

Primary axis (e.g. x): The categories to create bars for. If missing all records will be shown in the same bar
Secondary axis (e.g. y): The height of the bars. If missing, it will be calculated by the layer
colour: The default colour of each bar
stroke: The colour of the stroke around each bar. Overrides colour
fill: The fill colour of each bar. Overrides colour
opacity: The opacity of the bar fill
linewidth: The width of the stroke
linetype: The type of stroke, i.e. the dashing pattern

Settings

position: Position adjustment. One of 'identity', 'stack' (default), 'dodge', or 'jitter'
width: The width of the bars as a proportion of the available width (0 to 1)

Data transformation

If the secondary axis has not been mapped the layer will calculate counts for you and display these as the secondary axis.

Properties

weight: If mapped, the sum of the weights within each group is calculated instead of the count in each group

Calculated statistics

count: The count or, if weight have been mapped, sum of weights in each group.
proportion: The groupwise proportion, i.e. the count divided by the sum of count within each group

Default remappings

count AS <secondary axis>: By default the barplot will show count as the height of the bars

Orientation

Bar plots have categories along their primary axis. The orientation is deduced directly from the mapping. To create a horizontal bar plot you map the categories to y instead of x (assuming a default Cartesian coordinate system).

Examples

Show the number of each species in the data

VISUALISE FROM ggsql:penguins
DRAW bar
  MAPPING species AS x

Use weight to instead show the collective mass of each species

VISUALISE FROM ggsql:penguins
DRAW bar
  MAPPING species AS x, body_mass AS weight

Map fill to a discrete value to create a stacked bar chart

VISUALISE FROM ggsql:penguins
DRAW bar
  MAPPING species AS x, island AS fill

Or change the position setting to e.g. get a dodged bar chart

VISUALISE FROM ggsql:penguins
DRAW bar
  MAPPING species AS x, sex AS fill
  SETTING position => 'dodge'

Map to y if the dataset already contains the value you want to show

SELECT species, MAX(body_mass) AS max_mass FROM ggsql:penguins
GROUP BY species
VISUALISE
DRAW bar
  MAPPING species AS x, max_mass AS y

Use together with a binned scale as an alternative to the histogram layer

VISUALISE FROM ggsql:penguins
DRAW bar
  MAPPING body_mass AS x
SCALE BINNED x
  SETTING breaks => 10

Create a horizontal bar plot by changing the mapping

VISUALISE FROM ggsql:penguins
DRAW bar
  MAPPING species AS y

And use with a polar coordinate system to create a pie chart

VISUALISE FROM ggsql:penguins
DRAW bar
  MAPPING species AS fill
PROJECT TO polar