Determine whether a vector is all of the same sign

Source: R/all_same_sign.R

Present since hutils 1.2.0.

all_same_sign(x)

Arguments

x

A numeric vector.

Value

TRUE if all elements of x have the same sign. Zero is a separate sign from positive and negative. All vectors of length-1 or length-0 return TRUE, even if x = NA, (since although the value is unknown, it must have a unique sign), and non-numeric x.

Examples

all_same_sign(1:10)
#> [1] TRUE
all_same_sign(1:10 - 1)
#> [1] FALSE
all_same_sign(0)
#> [1] TRUE
all_same_sign(NA)
#> [1] TRUE
all_same_sign(c(NA, 1))
#> [1] NA
all_same_sign("surprise?")
#> [1] TRUE
all_same_sign(c(0, 0.1 + 0.2 - 0.3))
#> [1] FALSE

if (requireNamespace("microbenchmark", quietly = TRUE)) {
  library(microbenchmark)
  microbenchmark(base = length(unique(sign(1:1e5), nmax = 3)) == 1L,
                 all_same_sign(1:1e5))
}
#> Unit: microseconds
#>                    expr    min     lq     mean  median     uq    max neval cld
#>                    base 1989.9 2026.0 2304.361 2039.65 2071.8 9020.1   100   b
#>  all_same_sign(1:1e+05)   86.3   87.7  100.670   96.25  104.5  173.1   100  a 
# Unit: microseconds
#                   expr  min   lq mean median   uq  max neval cld
#                   base 2012 2040 2322   2047 2063 9324   100   b
# all_same_sign(1:1e+05)   86   86   94     89   93  290   100  a