I am wondering if there is any function in R for upsampling since I could not find anything even close to Matlab upsample(x, upsampling_factor). There are functions with the name upsample but they are very confusing to use, I need pretty much something that adds predefined zeros between two numbers. Any other functions that take the input signal X like [1,2,3,4] and turn it to something like [1 0 0 2 0 0 3 0 0 4 0 0] is fine. This is like upsampling factor 3.
Taking a lead from here a few options:
upsample1 = function(x, upsampling_factor)
c(rbind(x, matrix(0, nc=length(x), nr=upsampling_factor-1)))
upsample2 = function(x, upsampling_factor){
v = numeric(length(x)*upsampling_factor)
v[seq(1, length(x)*upsampling_factor, by=upsampling_factor)]=x
v
}
upsample3 = function(x, upsampling_factor)
c(kronecker(x, c(1, rep(0, upsampling_factor-1))))
# d.b -- this looks a wee bit faster
upsample4 = function(x, upsampling_factor)
replace(rep(0, upsampling_factor * length(x)),
1:(upsampling_factor*length(x)) %% upsampling_factor == 1, x)
For interest
all.equal(upsample1(x=1e5, 4), upsample2(x=1e5, 4))
all.equal(upsample3(x=1e5, 4), upsample2(x=1e5, 4))
microbenchmark::microbenchmark(upsample1(x=1e5, 4),
upsample2(x=1e5, 4),
upsample3(x=1e5, 4),
upsample4(x=1e5, 4))
# Unit: microseconds
# expr min lq mean median uq max neval cld
# upsample1(x = 1e+05, 4) 9.080 10.6515 11.72813 11.8735 12.4325 24.025 100 a
# upsample2(x = 1e+05, 4) 38.902 42.6740 45.14167 44.1400 46.4450 90.864 100 b
# upsample3(x = 1e+05, 4) 62.368 65.8610 69.69082 67.4325 70.6795 187.455 100 c
# upsample4(x = 1e+05, 4) 7.613 8.8705 9.57149 9.5690 10.0570 19.137 100 a