Introduction to gglasso

Install the package

# on CRAN
install.packages("gglasso")

# dev version on GitHub
pacman::p_load_gh('emeryyi/gglasso')

Least squares regression

library(gglasso)

# load bardet data set
data(bardet)

group1 <- rep(1:20, each = 5)

fit_ls <- gglasso(x = bardet$x, y = bardet$y, group = group1, loss = "ls")

plot(fit_ls)

coef(fit_ls)[1:5,90:100]
##                      s89          s90          s91          s92          s93
## (Intercept)  8.099354325  8.098922472  8.098531366  8.098175719  8.097849146
## V1          -0.119580203 -0.120877799 -0.122079683 -0.123223779 -0.124310183
## V2          -0.113742329 -0.114834411 -0.115853997 -0.116837630 -0.117782854
## V3          -0.002584792 -0.003487571 -0.004328519 -0.005134215 -0.005904892
## V4          -0.084771705 -0.088304073 -0.091674509 -0.094978960 -0.098212775
##                      s94          s95          s96          s97          s98
## (Intercept)  8.097574095  8.097295166  8.097058895  8.096833259  8.096637676
## V1          -0.125274109 -0.126284595 -0.127173301 -0.128011016 -0.128738414
## V2          -0.118630121 -0.119526679 -0.120326451 -0.121086672 -0.121754134
## V3          -0.006593702 -0.007323107 -0.007970047 -0.008583011 -0.009116809
## V4          -0.101161988 -0.104349829 -0.107241330 -0.110045942 -0.112543755
##                      s99
## (Intercept)  8.096455264
## V1          -0.129453437
## V2          -0.122415680
## V3          -0.009645386
## V4          -0.115058449

Cross-Validation

cvfit_ls <- cv.gglasso(x = bardet$x, y = bardet$y, group = group1, loss = "ls")

plot(cvfit_ls)

coef(cvfit_ls, s = "lambda.min")
##                         1
## (Intercept)  8.188159e+00
## V1          -2.920404e-02
## V2          -6.260109e-02
## V3           3.778408e-02
## V4           8.687388e-03
## V5          -8.859391e-02
## V6          -1.917990e-04
## V7           1.154126e-03
## V8           1.134775e-03
## V9           1.375735e-04
## V10         -1.803483e-03
## V11          3.013438e-02
## V12         -4.004602e-02
## V13         -6.794145e-03
## V14          8.109610e-03
## V15         -5.928599e-02
## V16         -1.546346e-03
## V17          4.609510e-02
## V18         -2.604565e-02
## V19         -4.389721e-03
## V20         -6.305305e-02
## V21          4.003787e-02
## V22          9.184201e-02
## V23         -4.403054e-02
## V24         -2.419818e-02
## V25         -1.597623e-01
## V26          1.237461e-01
## V27          2.623245e-02
## V28         -3.587628e-02
## V29          1.594558e-02
## V30         -1.875068e-01
## V31         -2.663886e-02
## V32          1.306416e-02
## V33          4.911749e-03
## V34          1.682876e-02
## V35          2.623702e-02
## V36          4.044955e-02
## V37         -1.269815e-02
## V38          5.584653e-03
## V39          1.161722e-02
## V40         -5.532465e-02
## V41         -2.726735e-03
## V42         -3.547834e-03
## V43          1.317188e-03
## V44          8.437427e-03
## V45          4.023073e-03
## V46         -1.063313e-01
## V47          8.810500e-02
## V48          1.009493e-01
## V49          1.711919e-02
## V50          2.499672e-02
## V51         -9.420268e-03
## V52          1.250468e-02
## V53          9.582327e-02
## V54          1.612372e-01
## V55          3.603498e-02
## V56          5.235399e-04
## V57         -1.333945e-05
## V58         -1.657585e-03
## V59          2.294992e-03
## V60          6.384236e-04
## V61         -5.603876e-02
## V62          3.572879e-02
## V63          3.379915e-03
## V64          8.641343e-02
## V65          2.367518e-01
## V66         -3.549915e-02
## V67          1.250114e-02
## V68          2.605464e-02
## V69          4.405841e-02
## V70          2.679824e-03
## V71         -7.724819e-03
## V72         -1.259015e-03
## V73          2.855898e-02
## V74         -5.028518e-03
## V75          6.201713e-03
## V76         -1.765083e-02
## V77          2.514867e-02
## V78          5.464928e-02
## V79         -1.087780e-02
## V80          1.661320e-02
## V81          5.503388e-03
## V82         -1.814688e-02
## V83          8.430385e-03
## V84          8.898539e-03
## V85         -2.486413e-02
## V86          4.534706e-03
## V87         -6.503766e-02
## V88         -2.233163e-03
## V89          4.839429e-02
## V90         -7.798514e-02
## V91          2.161202e-02
## V92         -7.751690e-03
## V93         -8.403776e-03
## V94          2.150891e-02
## V95         -2.723838e-02
## V96         -5.745993e-03
## V97          5.749582e-03
## V98         -8.963615e-04
## V99          6.827704e-04
## V100         8.933803e-03

Weight Least squares regression

We can also perform weighted least-squares regression by specifying loss='wls', and providing a \(n \times n\) weight matrix in the weights argument, where \(n\) is the number of observations. Note that cross-validation is NOT IMPLEMENTED for loss='wls'.

# generate weight matrix
times <- seq_along(bardet$y)
rho <- 0.5
sigma <- 1
H <- abs(outer(times, times, "-"))
V <- sigma * rho^H
p <- nrow(V)
V[cbind(1:p, 1:p)] <- V[cbind(1:p, 1:p)] * sigma

# reduce eps to speed up convergence for vignette build
fit_wls <- gglasso(x = bardet$x, y = bardet$y, group = group1, loss = "wls", 
                   weight = V, eps = 1e-4)

plot(fit_wls)

coef(fit_wls)[1:5,90:100]
##                     s89         s90         s91         s92         s93
## (Intercept)  8.09429262  8.09340481  8.09254573  8.09170743  8.09089247
## V1          -0.13922372 -0.14077803 -0.14222609 -0.14359110 -0.14487482
## V2          -0.15966042 -0.16117772 -0.16261019 -0.16397683 -0.16527730
## V3           0.03917529  0.03880296  0.03847035  0.03816594  0.03788642
## V4          -0.16548208 -0.17057112 -0.17546237 -0.18021267 -0.18481370
##                     s94         s95         s96         s97         s98
## (Intercept)  8.09011527  8.08935394  8.08862146  8.08793054  8.08727098
## V1          -0.14606257 -0.14719352 -0.14824987 -0.14921624 -0.15011520
## V2          -0.16649386 -0.16766459 -0.16877053 -0.16979410 -0.17075592
## V3           0.03763241  0.03739356  0.03717453  0.03697953  0.03680099
## V4          -0.18919074 -0.19347289 -0.19758499 -0.20145156 -0.20513769
##                     s99
## (Intercept)  8.08664325
## V1          -0.15094837
## V2          -0.17165664
## V3           0.03663899
## V4          -0.20863833