Ecfun (version 0.2-0)

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)

Arguments

x

an R object

Value

A logical as described above.

See Also

mode

Examples

# NOT RUN {
##
## 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
# }
# NOT RUN {
all.equal(mex4[,4], mex.)
# }