docxtools (version 0.3.0)

format_engr: Format numerical variables in engineering notation.

Description

Converts numeric variables in a data frame into character variables formatted in engineering notation. The formatted character variables are delimited with $...$ for rendering as inline math.

Usage

format_engr(x, sigdig = NULL, ambig_0_adj = FALSE)

Value

A data frame with numeric variables converted to formatted strings bounded by "$...$".

Arguments

x

A data frame with numeric variables to be formatted.

sigdig

An optional vector of significant digits.

ambig_0_adj

An optional logical to adjust the format to remove ambiguous trailing zeros. If TRUE, the decimal point is moved three places to the left. Default is FALSE.

Details

Engineering notation is a subset of scientific notation: the exponent of ten must be divisible by three. Powers of ten are written with a product symbol (the LaTeX \times symbol), not computer E-notation. The numerical output strings are bounded by $...$ for rendering in math mode.

The output format is "coefficient x 10^exponent" except for exponents equal to 0, 1, or 2. In these cases, the output format is floating-point.

The input argument is a data frame with at least one numeric variable. Only double variables (not integers and not dates) are formatted in powers of ten.

The function distinguishes between integers that represent factors and those that represent numerical integers. Numerical integers are returned as characters in math mode. Factors and other non-numeric variables are returned unaffected.

Each double variable (except dates) can be assigned its own number of significant digits. The default is 4. If sigdig is a single value, it is used for all variables; if a vector, it must have the same number of elements as there are double variables in the data frame. Setting sigdig = 0 returns the double variables as characters but unaltered.

For numbers with no decimal point, trailing zeros can be ambiguous. Such numbers can be optionally reported with the decimal moved an additional three places to the left.

To learn more about docxtools, start with the vignettes: browseVignettes(package = "docxtools").

Examples

# Factors unaffected; ambiguous trailing zeros.
data("CO2")
x <- as.data.frame(head(CO2, n = 5L))
format_engr(x)
format_engr(x, sigdig = c(0, 3))
format_engr(x, sigdig = c(3, 3), ambig_0_adj = TRUE)

# Ordered factor unaffected; ambiguous trailing zeros.
data("DNase")
x <- as.data.frame(tail(DNase, n = 5L))
format_engr(x)
format_engr(x, sigdig = c(6, 3))
format_engr(x, sigdig = c(6, 3), ambig_0_adj = TRUE)

# Integers returned unchanged but delimited; NA unchanged.
data("airquality")
x <- head(airquality, n = 6L)
format_engr(x, sigdig = 3)