ggplot2 (version 0.9.0)

scale_x_date: Position scale, date

Description

Position scale, date

Usage

scale_x_date(..., expand = c(0.05, 0), breaks = waiver(),
    minor_breaks = waiver())
  scale_y_date(..., expand = c(0.05, 0), breaks = waiver(),
    minor_breaks = waiver())

Arguments

breaks

A vector of breaks, a function that given the scale limits returns a vector of breaks, or a character vector, specifying the width between breaks. For more information about the first two, see continu

minor_breaks

Either NULL for no minor breaks, waiver() for the default breaks (one minor break between each major break), a numeric vector of positions, or a function that given the limits returns a vector of minor breaks.

...

common continuous scale parameters: name, breaks, labels, na.value, limits and trans. See continuous_scale for m

expand

a numeric vector of length two giving multiplicative and additive expansion constants. These constants ensure that the data is placed some distance away from the axes.

See Also

Other position scales: scale_x_continuous, scale_x_datetime, scale_x_discrete, scale_x_log10, scale_x_reverse, scale_x_sqrt, scale_y_continuous, scale_y_datetime, scale_y_discrete, scale_y_log10, scale_y_reverse, scale_y_sqrt

Examples

# We'll start by creating some nonsense data with dates
df <- data.frame(
  date = seq(Sys.Date(), len=100, by="1 day")[sample(100, 50)],
  price = runif(50)
)
df <- df[order(df$date), ]
dt <- qplot(date, price, data=df, geom="line") + opts(aspect.ratio = 1/4)

# We can control the format of the labels, and the frequency of
# the major and minor tickmarks.  See ?format.Date and ?seq.Date
# for more details.
library(scales) # to access breaks/formatting functions
dt + scale_x_date()
dt + scale_x_date(labels = date_format("%m/%d"))
dt + scale_x_date(labels = date_format("%W"))
dt + scale_x_date(labels = date_format("%W"), breaks = date_breaks("week"))

dt + scale_x_date(breaks = date_breaks("months"),
  labels = date_format("%b"))
dt + scale_x_date(breaks = date_breaks("4 weeks"),
  labels = date_format("%d-%b"))

# We can use character string for breaks.
# See \\code{\\link{by}} argument in \\code{\\link{seq.Date}}.
dt + scale_x_date(breaks = "2 weeks")
dt + scale_x_date(breaks = "1 month", minor_breaks = "1 week")

# The date scale will attempt to pick sensible defaults for
# major and minor tick marks
qplot(date, price, data=df[1:10,], geom="line")
qplot(date, price, data=df[1:4,], geom="line")

df <- data.frame(
  date = seq(Sys.Date(), len=1000, by="1 day"),
  price = runif(500)
)
qplot(date, price, data=df, geom="line")

# A real example using economic time series data
qplot(date, psavert, data=economics)
qplot(date, psavert, data=economics, geom="path")

end <- max(economics$date)
last_plot() + scale_x_date(limits = c(as.Date("2000-1-1"), end))
last_plot() + scale_x_date(limits = c(as.Date("2005-1-1"), end))
last_plot() + scale_x_date(limits = c(as.Date("2006-1-1"), end))

# If we want to display multiple series, one for each variable
# it's easiest to first change the data from a "wide" to a "long"
# format:
library(reshape2) # for melt
em <- melt(economics, id = "date")

# Then we can group and facet by the new "variable" variable
qplot(date, value, data = em, geom = "line", group = variable)
qplot(date, value, data = em, geom = "line", group = variable) +
  facet_grid(variable ~ ., scale = "free_y")