1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/geom-bar.r, R/geom-col.r, R/stat-count.r
\name{geom_bar}
\alias{geom_bar}
\alias{geom_col}
\alias{stat_count}
\title{Bars charts}
\usage{
geom_bar(mapping = NULL, data = NULL, stat = "count",
position = "stack", ..., width = NULL, binwidth = NULL, na.rm = FALSE,
show.legend = NA, inherit.aes = TRUE)
geom_col(mapping = NULL, data = NULL, position = "stack", ...,
width = NULL, na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)
stat_count(mapping = NULL, data = NULL, geom = "bar",
position = "stack", ..., width = NULL, na.rm = FALSE,
show.legend = NA, inherit.aes = TRUE)
}
\arguments{
\item{mapping}{Set of aesthetic mappings created by \code{\link{aes}} or
\code{\link{aes_}}. If specified and \code{inherit.aes = TRUE} (the
default), it is combined with the default mapping at the top level of the
plot. You must supply \code{mapping} if there is no plot mapping.}
\item{data}{The data to be displayed in this layer. There are three
options:
If \code{NULL}, the default, the data is inherited from the plot
data as specified in the call to \code{\link{ggplot}}.
A \code{data.frame}, or other object, will override the plot
data. All objects will be fortified to produce a data frame. See
\code{\link{fortify}} for which variables will be created.
A \code{function} will be called with a single argument,
the plot data. The return value must be a \code{data.frame.}, and
will be used as the layer data.}
\item{position}{Position adjustment, either as a string, or the result of
a call to a position adjustment function.}
\item{...}{other arguments passed on to \code{\link{layer}}. These are
often aesthetics, used to set an aesthetic to a fixed value, like
\code{color = "red"} or \code{size = 3}. They may also be parameters
to the paired geom/stat.}
\item{width}{Bar width. By default, set to 90\% of the resolution of the data.}
\item{binwidth}{\code{geom_bar} no longer has a binwidth argument - if
you use it you'll get an warning telling to you use
\code{\link{geom_histogram}} instead.}
\item{na.rm}{If \code{FALSE}, the default, missing values are removed with
a warning. If \code{TRUE}, missing values are silently removed.}
\item{show.legend}{logical. Should this layer be included in the legends?
\code{NA}, the default, includes if any aesthetics are mapped.
\code{FALSE} never includes, and \code{TRUE} always includes.}
\item{inherit.aes}{If \code{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. \code{\link{borders}}.}
\item{geom, stat}{Override the default connection between \code{geom_bar} and
\code{stat_count}.}
}
\description{
There are two types of bar charts: \code{geom_bar} makes the height of the
bar proportional to the number of cases in each group (or if the
\code{weight} aethetic is supplied, the sum of the weights). If you want the
heights of the bars to represent values in the data, use
\link{geom_col} instead. \code{geom_bar} uses \code{stat_count} by
default: it counts the number of cases at each x position. \code{geom_col}
uses \code{stat_identity}: it leaves the data as is.
}
\details{
A bar chart uses height to represent a value, and so the base of the
bar must always be shown to produce a valid visual comparison. Naomi Robbins
has a nice
\href{http://www.b-eye-network.com/view/index.php?cid=2468}{article on this
topic}. This is why it doesn't make sense to use a log-scaled y axis with a
bar chart.
By default, multiple bar occupying the same \code{x} position will be
stacked atop one another by \code{\link{position_stack}}. If you want them
to be dodged side-to-side, use \code{\link{position_dodge}}. Finally,
\code{\link{position_fill}} shows relative proportions at each \code{x} by
stacking the bars and then standardising each bar to have the same height.
}
\section{Aesthetics}{
\aesthetics{geom}{bar}
}
\section{Computed variables}{
\describe{
\item{count}{number of points in bin}
\item{prop}{groupwise proportion}
}
}
\examples{
# geom_bar is designed to make it easy to create bar charts that show
# counts (or sums of weights)
g <- ggplot(mpg, aes(class))
# Number of cars in each class:
g + geom_bar()
# Total engine displacement of each class
g + geom_bar(aes(weight = displ))
# To show (e.g.) means, you need geom_col()
# And, even more succinctly with geom_col()
df <- data.frame(trt = c("a", "b", "c"), outcome = c(2.3, 1.9, 3.2))
ggplot(df, aes(trt, outcome)) +
geom_col()
# But geom_point() displays exactly the same information and doesn't
# require the y-axis to touch zero.
ggplot(df, aes(trt, outcome)) +
geom_point()
# You can also use geom_bar() with continuous data, in which case
# it will show counts at unique locations
df <- data.frame(x = rep(c(2.9, 3.1, 4.5), c(5, 10, 4)))
ggplot(df, aes(x)) + geom_bar()
# cf. a histogram of the same data
ggplot(df, aes(x)) + geom_histogram(binwidth = 0.5)
\donttest{
# Bar charts are automatically stacked when multiple bars are placed
# at the same location
g + geom_bar(aes(fill = drv))
# You can instead dodge, or fill them
g + geom_bar(aes(fill = drv), position = "dodge")
g + geom_bar(aes(fill = drv), position = "fill")
# To change plot order of bars, change levels in underlying factor
reorder_size <- function(x) {
factor(x, levels = names(sort(table(x))))
}
ggplot(mpg, aes(reorder_size(class))) + geom_bar()
}
}
\seealso{
\code{\link{geom_histogram}} for continuous data,
\code{\link{position_dodge}} for creating side-by-side barcharts.
\code{\link{stat_bin}}, which bins data in ranges and counts the
cases in each range. It differs from \code{stat_count}, which counts the
number of cases at each x position (without binning into ranges).
\code{\link{stat_bin}} requires continuous x data, whereas
\code{stat_count} can be used for both discrete and continuous x data.
}
|
