| warnings | R Documentation |
warnings and its print method print the
variable last.warning in a pleasing form.
warnings(...)
## S3 method for class 'warnings'
summary(object, ...)
## S3 method for class 'warnings'
print(x, tags,
header = ngettext(n, "Warning message:\n", "Warning messages:\n"),
...)
## S3 method for class 'summary.warnings'
print(x, ...)
... |
arguments to be passed to |
object |
a |
x |
a |
tags |
if not |
header |
a character string |
See the description of options("warn") for the
circumstances under which there is a last.warning object and
warnings() is used. In essence this is if options(warn =
0) and warning has been called at least once.
Note that the length(last.warning) is maximally
getOption("nwarnings") (at the time the warnings are
generated) which is 50 by default. To increase, use something
like
options(nwarnings = 10000)
It is possible that last.warning refers to the last recorded
warning and not to the last warning, for example if options(warn) has
been changed or if a catastrophic error occurred.
warnings() returns an object of S3 class "warnings", basically a named
list.
summary(<warnings>) returns a "summary.warnings"
object which is basically the list of unique warnings
(unique(object)) with a "counts" attribute, somewhat
experimentally.
It is undocumented where last.warning is stored nor that it is
visible, and this is subject to change.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
warning.
## NB this example is intended to be pasted in,
## rather than run by example()
ow <- options("warn")
for(w in -1:1) {
options(warn = w); cat("\n warn =", w, "\n")
for(i in 1:3) { cat(i,"..\n"); m <- matrix(1:7, 3,4) }
cat("--=--=--\n")
}
## at the end prints all three warnings, from the 'option(warn = 0)' above
options(ow) # reset to previous, typically 'warn = 0'
tail(warnings(), 2) # see the last two warnings only (via '[' method)
## Often the most useful way to look at many warnings:
summary(warnings())
op <- options(nwarnings = 10000) ## <- get "full statistics"
x <- 1:36; for(n in 1:13) for(m in 1:12) A <- matrix(x, n,m) # There were 105 warnings ...
summary(warnings())
options(op) # revert to previous (keeping 50 messages by default)
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