Functions & Arguments

Published

December 16, 2022

2 types of bar charts :

  • geom_bar()

    • geom_bar() uses stat_count() by default: it counts the number of cases at each x position.

  • geom_col(). geom_bar() makes the height of the bar proportional to the number of cases in each group (or if the weight aesthetic is supplied, the sum of the weights)

    • geom_col() for the heights of the bars to represent values in the data, uses stat_identity(): it leaves the data as is.

mapping = NULL,

data = NULL,

stat = “count”,

computed variables can be either “count” or “prop”

position = “stack”,

…,

  • Often aesthetics arguments, e.g. colour = “red” or size = 3

just = 0.5,

  • Adjustment for column placement.

  • Default = 0.5 = columns to be centered about axis breaks.

  • Set to 0 or 1 to place columns to the left / right of axis breaks.

width = NULL,

  • Bar width.

  • Default = 90% of the resolution( ) of the data.

  • For discrete variable, the resolution is 1.

na.rm = FALSE,

  • Default = FALSE = missing values are removed with a warning.

  • TRUE = missing values are silently removed.

orientation = NA,

show.legend = NA,

  • Default = NA = includes if any aesthetics are mapped.

  • FALSE = never includes, and TRUE always includes.

inherit.aes = TRUE

Example : flip the bar chart orientation by mapping variable to y

ggplot(mpg) + geom_bar(aes(y = class))

Example : auto stacked

g <- ggplot(mpg, aes(class)) g + geom_bar(aes(fill = drv))

Example : auto stacked horizontally

ggplot(mpg, aes( y = class)) + geom_bar(aes( fill = drv), position = position_stack(reverse = TRUE)) + theme(legend.position = “top”)

mapping = NULL,

data = NULL,

position = “stack”,

…,

just = 0.5,

width = NULL,

na.rm = FALSE,

show.legend = NA,

inherit.aes = TRUE

stat_identity(

mapping = NULL,

data = NULL,

geom = “point”,

position = “identity”,

…,

show.legend = NA,

inherit.aes = TRUE

Example for stat_identity( )

p <- ggplot(mtcars,

aes(wt, mpg))

p + stat_identity( )