R: Rounding of Numbers: Zapping Small Ones to Zero

zapsmall {base}

R Documentation

Rounding of Numbers: Zapping Small Ones to Zero

Description

zapsmall determines a digits argument dr for calling round(x, digits = dr) such that values close to zero (compared with the maximal absolute value in the vector) are ‘zapped’, i.e., replaced by 0.

Usage

zapsmall(x, digits = getOption("digits"),
         mFUN = function(x, ina) max(abs(x[!ina])),
         min.d = 0L)

Arguments

`x`	a numeric or complex vector or any R number-like object which has a `round` method and basic arithmetic methods including `log10()`.
`digits`	integer indicating the precision to be used.
`mFUN`	a `function(x, ina)` of the numeric (or complex) `x` and the `logical` `ina := is.na(x)` returning a positive number in the order of magnitude of the maximal `abs(x)` value. The default is back compatible but not robust, and e.g., not very useful when `x` has infinite entries.
`min.d`	an integer specifying the minimal number of digits to use in the resulting `round(x, digits=)` call when `mFUN() > 0`.

References

Chambers, J. M. (1998) Programming with Data. A Guide to the S Language. Springer.

Examples

x2 <- pi * 100^(-2:2)/10
   print(  x2, digits = 4)
zapsmall(  x2) # automatic digits
zapsmall(  x2, digits = 4)
zapsmall(c(x2, Inf)) # round()s to integer ..
zapsmall(c(x2, Inf), min.d=-Inf) # everything  is small wrt  Inf

(z <- exp(1i*0:4*pi/2))
zapsmall(z)

zapShow <- function(x, ...) rbind(orig = x, zapped = zapsmall(x, ...))
zapShow(x2)

## using a *robust* mFUN
mF_rob <- function(x, ina) boxplot.stats(x, do.conf=FALSE)$stats[5]
## with robust mFUN(), 'Inf' is no longer distorting the picture:
zapShow(c(x2, Inf), mFUN = mF_rob)
zapShow(c(x2, Inf), mFUN = mF_rob, min.d = -5) # the same
zapShow(c(x2, 999), mFUN = mF_rob) # same *rounding* as w/ Inf
zapShow(c(x2, 999), mFUN = mF_rob, min.d =  3) # the same
zapShow(c(x2, 999), mFUN = mF_rob, min.d =  8) # small diff

[Package base version 4.5.0 Index]