Ecfun (version 0.3-2)

canbeNumeric: Can a variable reasonably be coerced to numeric?

Description

Can seq be reasonably applied to x? Returns TRUE if yes and FALSE otherwise.

We'd like to use this with, for example, date-time objects in as.Date and as.POSIXct formats. However, as.numeric of such objects is FALSE. Moreover, as.numeric of factors is TRUE.

The current algorithm (which may change in the future) returns TRUE if (mode(x) == 'numeric') & (!('levels' %in% names(attributes(x)))).

Usage

canbeNumeric(x)

Value

A logical as described above.

Arguments

x

an R object

Author

Spencer Graves

See Also

mode

Examples

##
## Examples adapted from "mode"
##
cex4 <- c('letters[1:4]', "as.Date('2014-01-02')", 
  'factor(letters[1:4])', "NULL", "1", "1:1", "1i", 
  "list(1)", "data.frame(x = 1)","pairlist(pi)", 
  "c", "lm", "formals(lm)[[1]]",  "formals(lm)[[2]]",
  "y ~ x","expression((1))[[1]]", "(y ~ x)[[1]]",
  "expression(x <- pi)[[1]][[1]]")
lex4 <- sapply(cex4, function(x) eval(parse(text = x)))
mex4 <- t(sapply(lex4, function(x) 
    c(typeof(x), storage.mode(x), mode(x), canbeNumeric(x))))
dimnames(mex4) <- list(cex4, 
    c("typeof(.)","storage.mode(.)","mode(.)", 'canbeNumeric(x)'))
mex4

# check 
mex. <- as.character(as.logical(c(0, 1, 0, 0, 1, 1, rep(0, 12))))
names(mex.) <- cex4
stopifnot(
all.equal(mex4[,4], mex.)
)