collapse {dipsaus} | R Documentation |
Collapse Sensors And Calculate Summations/Mean
collapse(x, keep, average = FALSE)
x |
A numeric multi-mode tensor (array), without |
keep |
Which dimension to keep |
average |
collapse to sum or mean |
a collapsed array with values to be mean or summation along collapsing dimensions
# Example 1
x = matrix(1:16, 4)
# Keep the first dimension and calculate sums along the rest
collapse(x, keep = 1)
rowSums(x) # Should yield the same result
# Example 2
x = array(1:120, dim = c(2,3,4,5))
result = collapse(x, keep = c(3,2))
compare = apply(x, c(3,2), sum)
sum(abs(result - compare)) # The same, yield 0 or very small number (1e-10)
# Example 3 (performance)
# Small data, no big difference, even slower
x = array(rnorm(240), dim = c(4,5,6,2))
microbenchmark::microbenchmark(
result = collapse(x, keep = c(3,2)),
compare = apply(x, c(3,2), sum),
times = 1L, check = function(v){
max(abs(range(do.call('-', v)))) < 1e-10
}
)
# large data big difference
x = array(rnorm(prod(300,200,105)), c(300,200,105,1))
microbenchmark::microbenchmark(
result = collapse(x, keep = c(3,2)),
compare = apply(x, c(3,2), sum),
times = 1L , check = function(v){
max(abs(range(do.call('-', v)))) < 1e-10
})