ggvis (version 0.4.9)

scale_datetime: Add a date-time scale to a ggvis object.

Description

A date/time scale controls the mapping of date and time variables to visual properties.

Usage

scale_datetime(
  vis,
  property,
  domain = NULL,
  range = NULL,
  reverse = NULL,
  round = NULL,
  utc = NULL,
  clamp = NULL,
  nice = NULL,
  expand = NULL,
  name = property,
  label = NULL,
  override = NULL
)

Arguments

vis

A ggvis object.

property

The name of a property, such as "x", "y", "fill", "stroke", etc.

domain

The domain of the scale, representing the set of data values. For ordinal scales, a character vector; for quantitative scales, a numeric vector of length two. Either value (but not both) may be NA, in which case domainMin or domainMax is set. For dynamic scales, this can also be a reactive which returns the appropriate type of vector.

range

The range of the scale, representing the set of visual values. For numeric values, the range can take the form of a two-element array with minimum and maximum values. For ordinal data, the range may by an array of desired output values, which are mapped to elements in the specified domain. The following range literals are also available: "width", "height", "shapes", "category10", "category20".

reverse

If true, flips the scale range.

round

If true, rounds numeric output values to integers. This can be helpful for snapping to the pixel grid.

utc

if TRUE, uses UTC times. Default is FALSE.

clamp

If TRUE, values that exceed the data domain are clamped to either the minimum or maximum range value. Default is FALSE.

nice

If specified, modifies the scale domain to use a more human-friendly value range. Should be a string indicating the desired time interval; legal values are "second", "minute", "hour", "day", "week", "month", or "year".

expand

A multiplier for how much the scale should be expanded beyond the domain of the data. For example, if the data goes from 10 to 110, and expand is 0.05, then the resulting domain of the scale is 5 to 115. Set to 0 and use nice=FALSE if you want exact control over the domain.

name

Name of the scale, such as "x", "y", "fill", etc. Can also be an arbitrary name like "foo".

label

Label for the scale. Used for axis or legend titles.

override

Should the domain specified by this ggvis_scale object override other ggvis_scale objects for the same scale? Useful when domain is manually specified. For example, by default, the domain of the scale will contain the range of the data, but when this is TRUE, the specified domain will override, and the domain can be smaller than the range of the data. If FALSE, the domain will not behave this way. If left NULL, then it will be treated as TRUE whenever domain is non-NULL.

See Also

scales, scale_numeric, https://vega.github.io/vega/docs/scales/#time

Other scales: scale_numeric(), scale_ordinal()

Examples

set.seed(2934)
dat <- data.frame(
  time = as.Date("2013-07-01") + 1:100,
  value = seq(1, 10, length.out = 100) + rnorm(100)
)
p <- dat %>% ggvis(~time, ~value) %>% layer_points()

# Start and end on month boundaries
p %>% scale_datetime("x", nice = "month")


dist <- data.frame(times = as.POSIXct("2013-07-01", tz = "GMT") +
                           rnorm(200) * 60 * 60 * 24 * 7)
p <- dist %>% ggvis(x = ~times) %>% layer_histograms()
p

# Start and end on month boundaries
p %>% scale_datetime("x", nice = "month")

p %>% scale_datetime("x", utc = TRUE)