convertUnits {precisePlacement}

Convert Between Different Available Units That Measure Points on a Plot

Description

Convert Between Different Available Units That Measure Points on a Plot

Usage

convertUnits(from, value, to, side = NULL, axis = NULL, region = "plot")

Arguments

from

Units one wishes to convert from. Allowed values are "line", "data", and "proportion".

value

Numeric value(s) of the coordinate(s) one wishes to convert.

to

Units one wishes to convert from. Allowed values are "line", "data", and "proportion".

side

Integer giving the side of the plot to count lines from.

axis

One of "x" or "y", giving the axis a proportion should be calculated from.

region

Required when either from or to has the value "proportion". Must be one of "device", "figure", "plot", or "data". Defaults to "plot".

Value

Numeric value(s) of the input coordinates converted into the new units.

Author(s)

Jasper Watson

Examples

## Not run: 

## Illustrate where the lines fall when using mtext:

plot(1:10)
mtext(1:26, line = -(1:26), side = 1, col = 'blue')
x <- convertUnits('line', 0:(-26), 'data', side = 1)
abline(h = x, col = 'red', lty = 2)

## Show how proportions of a plot can be identified:

plot(seq(as.Date('2018-01-01'), as.Date('2019-01-01'), length.out = 10), 1:10,
     pch = 19)

## Identify the "center" of the plot.
abline(h = convertUnits('proportion', 0.5, 'data', axis = 'y'),
       col = 'red', lwd = 4)
abline(v = convertUnits('proportion', 0.5, 'data', axis = 'x'),
       col = 'blue', lwd = 4)

print(convertUnits('proportion', 0.5, 'data', axis = 'y'))
## as.Date is needed because convertUnits returns a numeric value.
print(as.Date(convertUnits('proportion', 0.5, 'data', axis = 'x'),
      origin = '1970-01-01'))

## Change the region we are defining the proportions from.
abline(v = convertUnits('proportion', 0.75, 'data', axis = 'x', region = 'plot'),
       col = 'darkgreen', lwd = 4)
abline(v = convertUnits('proportion', 0.75, 'data', axis = 'x', region = 'device'),
       col = 'orange', lwd = 4)


## End(Not run)