knitr::opts_chunk$set(echo = TRUE)
GLASSO
is an R package that estimates a penalized precision matrix via block-wise coordinate descent -- also known as the graphical lasso (glasso) algorithm. A (possibly incomplete) list of functions contained in the package can be found below:
GLASSO()
computes the estimated precision matrix
plot.GLASSO()
produces a heat map or line graph for cross validation errors
# The easiest way to install is from GitHub: # install.packages("devtools") devtools::install_github("MGallow/GLASSOO")
If there are any issues/bugs, please let me know: github. You can also contact me via my website. Pull requests are welcome!
library(GLASSOO) # generate data from a sparse matrix # first compute covariance matrix S = matrix(0.7, nrow = 5, ncol = 5) for (i in 1:5){ for (j in 1:5){ S[i, j] = S[i, j]^abs(i - j) } } # print oracle precision matrix (shrinkage might be useful) (Omega = round(qr.solve(S), 3)) # generate 100 x 5 matrix with rows drawn from iid N_p(0, S) set.seed(123) Z = matrix(rnorm(100*5), nrow = 100, ncol = 5) out = eigen(S, symmetric = TRUE) S.sqrt = out$vectors %*% diag(out$values^0.5) %*% t(out$vectors) X = Z %*% S.sqrt # calculate sample covariance Sample = (nrow(X) - 1)/nrow(X)*cov(X) # print sample precision matrix (perhaps a bad estimate) round(qr.solve(cov(X)), 5) # GLASSO (lam = 0.5) GLASSO(S = Sample, lam = 0.5) # GLASSO cross validation (GLASSO = GLASSO(X)) # produce line graph for CV errors for GLASSO plot(GLASSO) # produce CV heat map for GLASSO plot(GLASSO, type = "heatmap")
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