sparsio is a small (the only dependency is Rcpp) R package for sparse matrices Input/Output. It provides fast svmlight reader and writer.
read_svmlight()write_svmlight()
library(Matrix)
library(sparsio)
N = 1e8
i = sample(1e5, N, T)
j = sample(1e5, N, T)
vals = runif(N)
x = sparseMatrix(i, j, x = vals)
print(object.size(x), units = "Gb")
# 1.1 Gb
y = sample(c(0, 1), nrow(x), replace = TRUE)
f = tempfile(fileext = ".svmlight")
system.time(write_svmlight(x, y, f))
# user system elapsed
# 68.014 2.785 70.899
file.size(f)/1e9
# 1.48135 Gb
system.time(x2 <- read_svmlight(f, type = "CsparseMatrix"))
# user system elapsed
# 55.021 2.803 57.892
all.equal(x2$x, x)
# "Mean relative difference: 4.636406e-07"
all.equal(x2$y, y)
# TRUE