sfsmisc: missingCh – R documentation

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missingCh

Has a Formal Argument been Set or is it Missing?

Description

missingCh can be used to test whether a value was specified as an argument to a function. Very much related to the standard R function missing, here the argument is given by its name, a character string.

As missingCh() calls missing(), do consider the caveats about the latter, see missing.

Usage

missingCh(x, envir = parent.frame())

Arguments

`x`	a `character` string.
`envir`	a (function evaluation) `environment`, in which the variable named `x` is to be “missing”.

Value

a logical indicating if the argument named x is missing in the function “above”, typically the caller of missingCh, but see the use of envir in the vapply example.

Author(s)

Martin Maechler

Examples

tst1 <- function(a, b, dd, ...) ## does not work an with argument named 'c' !
    c(b = missingCh("b"), dd = missingCh("dd"))
tst1(2)#-> both 'b' and 'dd' are missing
tst1(,3,,3)
##     b    dd
## FALSE  TRUE  -- as 'b' is not missing but 'dd' is.

Tst <- function(a,b,cc,dd,EEE, ...)
    vapply(c("a","b","cc","dd","EEE"), missingCh, NA, envir=environment())
Tst()
## TRUE ... TRUE -- as all are missing()
Tst(1,,3)
##     a     b    cc    dd   EEE
## FALSE  TRUE FALSE  TRUE  TRUE
## .....       .....
## as 'a' and 'cc' where not missing()

## Formal testing:
stopifnot(tst1(), !tst1(,3,3), Tst(),
                        Tst(1,,3, b=2, E="bar") == c(0,0,1,0,0))
## maybe surprising that this ^^ becomes 'dd' and only 'cc' is missing

sfsmisc

Utilities from 'Seminar fuer Statistik' ETH Zurich

v1.1-11

GPL (>= 2)

Authors

Martin Maechler [aut, cre] (<https://orcid.org/0000-0002-8685-9910>), Werner Stahel [ctb] (Functions: compresid2way(), f.robftest(), last(), p.scales(), p.dnorm()), Andreas Ruckstuhl [ctb] (Functions: p.arrows(), p.profileTraces(), p.res.2x()), Christian Keller [ctb] (Functions: histBxp(), p.tachoPlot()), Kjetil Halvorsen [ctb] (Functions: KSd(), ecdf.ksCI()), Alain Hauser [ctb] (Functions: cairoSwd(), is.whole(), toLatex.numeric()*), Christoph Buser [ctb] (to function Duplicated()), Lorenz Gygax [ctb] (to function p.res.2fact()), Bill Venables [ctb] (Functions: empty.dimnames(), primes()), Tony Plate [ctb] (to inv.seq()), Isabelle Fl<fc>ckiger [ctb], Marcel Wolbers [ctb], Markus Keller [ctb], Sandrine Dudoit [ctb], Jane Fridlyand [ctb], Greg Snow [ctb] (to loessDemo()), Henrik Aa. Nielsen [ctb] (to loessDemo()), Vincent Carey [ctb], Ben Bolker [ctb], Philippe Grosjean [ctb], Fr<e9>d<e9>ric Ibanez [ctb], Caterina Savi [ctb], Charles Geyer [ctb], Jens Oehlschl<e4>gel [ctb]

Initial release

2021-04-03