/man/translate_qplot_ggplot.Rd

 1% Generated by roxygen2: do not edit by hand
 2% Please edit documentation in R/translate-qplot-ggplot.r
 3\name{translate_qplot_ggplot}
 4\alias{translate_qplot_ggplot}
 5\title{Translating between qplot and ggplot}
 6\description{
 7Within ggplot2, there are two basic methods to create plots, with qplot()
 8and ggplot(). qplot() is designed primarily for interactive use: it makes
 9a number of assumptions that speed most cases, but when designing multilayered
10plots with different data sources it can get in the way. This section
11describes what those defaults are, and how they map to the fuller ggplot()
12syntax.
13}
14\examples{
15
16# By default, qplot() assumes that you want a scatterplot,
17# i.e., you want to use geom_point()
18# qplot(x, y, data = data)
19# ggplot(data, aes(x, y)) + geom_point()
20
21# Using Aesthetics
22
23# If you map additional aesthetics, these will be added to the defaults. With
24# qplot() there is no way to use different aesthetic mappings (or data) in
25# different layers
26# qplot(x, y, data = data, shape = shape, colour = colour)
27# ggplot(data, aes(x, y, shape = shape, colour = colour)) + geom_point()
28#
29# Aesthetic parameters in qplot() always try to map the aesthetic to a
30# variable. If the argument is not a variable but a value, effectively a new column
31# is added to the original dataset with that value. To set an aesthetic to a
32# value and override the default appearance, you surround the value with I() in
33# qplot(), or pass it as a parameter to the layer.
34# qplot(x, y, data = data, colour = I("red"))
35# ggplot(data, aes(x, y)) + geom_point(colour = "red")
36
37# Changing the geom parameter changes the geom added to the plot
38# qplot(x, y, data = data, geom = "line")
39# ggplot(data, aes(x, y)) + geom_line()
40
41# Not all geoms require both x and y, e.g., geom_bar() and geom_histogram().
42# For these two geoms, if the y aesthetic is not supplied, both qplot and
43# ggplot commands default to "count" on the y-axis
44# ggplot(data, aes(x)) + geom_bar()
45# qplot(x, data = data, geom = "bar")
46
47# If a vector of multiple geom names is supplied to the geom argument, each
48# geom will be added in turn
49# qplot(x, y, data = data, geom = c("point", "smooth"))
50# ggplot(data, aes(x, y)) + geom_point() + geom_smooth()
51
52# Unlike the rest of ggplot2, stats and geoms are independent
53# qplot(x, y, data = data, stat = "bin")
54# ggplot(data, aes(x, y)) + geom_point(stat = "bin")
55#
56# Any layer parameters will be passed on to all layers. Most layers will ignore
57# parameters that they don't need
58# qplot(x, y, data = data, geom = c("point", "smooth"), method = "lm")
59# ggplot(data, aes(x, y)) + geom_point(method = "lm") + geom_smooth(method = "lm")
60
61# Scales and axes
62
63# You can control basic properties of the x and y scales with the xlim, ylim,
64# xlab and ylab arguments
65# qplot(x, y, data = data, xlim = c(1, 5), xlab = "my label")
66# ggplot(data, aes(x, y)) + geom_point() +
67# scale_x_continuous("my label", limits = c(1, 5))
68
69# qplot(x, y, data = data, xlim = c(1, 5), ylim = c(10, 20))
70# ggplot(data, aes(x, y)) + geom_point() +
71# scale_x_continuous(limits = c(1, 5)) + scale_y_continuous(limits = c(10, 20))
72
73# Like plot(), qplot() has a convenient way of log transforming the axes.
74# qplot(x, y, data = data, log = "xy")
75# ggplot(data, aes(x, y)) + geom_point() + scale_x_log10() + scale_y_log10()
76# There are many other possible transformations, but not all are
77# accessible from within qplot(), see ?scale_continuous for more
78
79# Plot options
80
81# qplot() recognises the same options as plot does, and converts them to their
82# ggplot2 equivalents. See ?theme for more on ggplot options
83# qplot(x, y, data = data, main="title", asp = 1)
84# ggplot(data, aes(x, y)) + geom_point() + labs(title = "title") + theme(aspect.ratio = 1)
85}
86