R: create axis label with appropriate labels

plot.units {units} | R Documentation

## create axis label with appropriate labels

### Description

create axis label with appropriate labels

plot unit objects

### Usage

    make_unit_label(lab, u, sep = units_options("sep"),
      group = units_options("group"), parse = units_options("parse"))

    ## S3 method for class 'units'
    plot(x, y, xlab = NULL, ylab = NULL, ...)

### Arguments

`lab` | length one character; name of the variable to plot
`u` | vector of class `units`
`sep` | length two character vector, defaulting to `c("~","~")`, with the white space between unit name and unit symbols, and between subsequent symbols.
`group` | length two character vector with grouping symbols, e.g. `c("(",")")` for parenthesis, or `c("","")` for no group symbols
`parse` | logical; indicates whether a parseable expression should be returned (typically needed for super scripts), or a simple character string without special formatting.
`x` | object of class units, to plot along the x axis, or, if y is missing, along the y axis
`y` | object to plot along the y axis, or missing
`xlab` | character; x axis label
`ylab` | character; y axis label
`...` | other parameters, passed on to plot.default

### Details

units_options can be used to set and change the defaults for `sep`, `group` and `doParse`.

### Examples

    oldpar = par(mar = par("mar") + c(0, .3, 0, 0))
    displacement = mtcars$disp * ud_units[["in"]]^3
    # an example that would break if parse were (default) TRUE, since 'in' is a reserved word:
    units_options(parse=FALSE)
    make_unit_label("displacement", displacement)
    units_options(parse=TRUE)
    units(displacement) = with(ud_units, cm^3)
    weight = mtcars$wt * 1000 * with(ud_units, lb)
    units(weight) = with(ud_units, kg)
    plot(weight, displacement)
    units_options(group = c("(", ")") )  # parenthesis instead of square brackets
    plot(weight, displacement)
    units_options(sep = c("~~~", "~"), group = c("", ""))  # no brackets; extra space
    plot(weight, displacement)
    units_options(sep = c("~", "~~"), group = c("[", "]"))
    gallon = as_units("gallon")
    consumption = mtcars$mpg * with(ud_units, mi/gallon)
    units(consumption) = with(ud_units, km/l)
    plot(displacement, consumption) # division in consumption
    units_options(negative_power = TRUE) # division becomes ^-1
    plot(displacement, consumption)
    plot(1/displacement, 1/consumption)
    par(oldpar)

[Package units version 0.5-1 Index]