cmls | R Documentation |
Finds the p
x m
matrix B
that minimizes the multivariate least squares problem
sum(( Y - X %*% B )^2)
|
subject to the specified constraints on the rows of B
.
cmls(X, Y, const = "uncons", struc = NULL,
z = NULL, df = 10, degree = 3, intercept = TRUE,
backfit = FALSE, maxit = 1e3, eps = 1e-10,
del = 1e-6, XtX = NULL, mode.range = NULL)
X |
Matrix of dimension |
Y |
Matrix of dimension |
const |
Constraint code. See |
struc |
Structural constraints (defaults to unstructured). See Note. |
z |
Predictor values for the spline basis (for smoothness constraints). See Note. |
df |
Degrees of freedom for the spline basis (for smoothness constraints). See Note. |
degree |
Polynomial degree for the spline basis (for smoothness constraints). See Note. |
intercept |
Logical indicating whether the spline basis should contain an intercept (for smoothness constraints). See Note. |
backfit |
Estimate |
maxit |
Maximum number of iterations for back-fitting algorithm. Ignored if |
eps |
Convergence tolerance for back-fitting algorithm. Ignored if |
del |
Stability tolerance for back-fitting algorithm. Ignored if |
XtX |
Crossproduct matrix: |
mode.range |
Mode search ranges (for unimodal constraints). See Note. |
If backfit = FALSE
(default), a closed-form solution is used to estimate B
whenever possible. Otherwise a back-fitting algorithm is used, where the rows of B
are updated sequentially until convergence. The backfitting algorithm is determined to have converged when
mean((B.new - B.old)^2) < eps * (mean(B.old^2) + del)
,
where B.old
and B.new
denote the parameter estimates at iterations t
and t+1
of the backfitting algorithm.
Returns the estimated matrix B
with attribute "df" (degrees of freedom), which gives the df for each row of B
.
Structure constraints (struc
) should be specified with a p
x m
matrix of logicals (TRUE/FALSE), such that FALSE elements indicate a weight should be constrained to be zero. Default uses unstructured weights, i.e., a p
x m
matrix of all TRUE values.
Inputs z
, df
, degree
, and intercept
are only applicable when using one of the 12 constraints that involves a spline basis, i.e., "smooth", "smonon", "smoper", "smpeno", "ortsmo", "orsmpe", "monsmo", "mosmno", "unismo", "unsmno", "unsmpe", "unsmpn".
Input mode.range
is only applicable when using one of the 8 constraints that enforces unimodality: "unimod", "uninon", "uniper", "unpeno", "unismo", "unsmno", "unsmpe", "unsmpn". Mode search ranges (mode.range
) should be specified with a 2 x p
matrix of integers such that
1 <= mode.range[1,j] <= mode.range[2,j] <= m
for all j = 1:p
.
Default is mode.range = matrix(c(1, m), 2, p)
.
Nathaniel E. Helwig <helwig@umn.edu>
Goldfarb, D., & Idnani, A. (1983). A numerically stable dual method for solving strictly convex quadratic programs. Mathematical Programming, 27, 1-33. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1007/BF02591962")}
Helwig, N. E. (in prep). Constrained multivariate least squares in R.
Ten Berge, J. M. F. (1993). Least Squares Optimization in Multivariate Analysis. Volume 25 of M & T Series. DSWO Press, Leiden University. ISBN: 9789066950832
Turlach, B. A., & Weingessel, A. (2019). quadprog: Functions to solve Quadratic Programming Problems. R package version 1.5-8. https://CRAN.R-project.org/package=quadprog
const
prints/returns the contraint options.
cv.cmls
performs k-fold cross-validation to tune the constraint options.
mlsei
and mlsun
are used to implement several of the constraints.
######***###### GENERATE DATA ######***######
# make X
set.seed(2)
n <- 50
m <- 20
p <- 2
Xmat <- matrix(rnorm(n*p), nrow = n, ncol = p)
# make B (which satisfies all constraints except monotonicity)
x <- seq(0, 1, length.out = m)
Bmat <- rbind(sin(2*pi*x), sin(2*pi*x+pi)) / sqrt(4.75)
struc <- rbind(rep(c(TRUE, FALSE), each = m / 2),
rep(c(FALSE, TRUE), each = m / 2))
Bmat <- Bmat * struc
# make noisy data
set.seed(1)
Ymat <- Xmat %*% Bmat + rnorm(n*m, sd = 0.25)
######***###### UNCONSTRAINED ######***######
# unconstrained
Bhat <- cmls(X = Xmat, Y = Ymat, const = "uncons")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unconstrained and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "uncons", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
######***###### NON-NEGATIVITY ######***######
# non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "nonneg")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "nonneg", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
######***###### PERIODICITY ######***######
# periodic
Bhat <- cmls(X = Xmat, Y = Ymat, const = "period")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# periodic and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "period", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# periodic and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "pernon")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# periodic and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "pernon", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
######***###### SMOOTHNESS ######***######
# smooth
Bhat <- cmls(X = Xmat, Y = Ymat, const = "smooth")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# smooth and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "smooth", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# smooth and periodic
Bhat <- cmls(X = Xmat, Y = Ymat, const = "smoper")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# smooth and periodic and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "smoper", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# smooth and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "smonon")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# smooth and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "smonon", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# smooth and periodic and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "smpeno")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# smooth and periodic and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "smpeno", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
######***###### ORTHOGONALITY ######***######
# orthogonal
Bhat <- cmls(X = Xmat, Y = Ymat, const = "orthog")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# orthogonal and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "orthog", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# orthgonal and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "ortnon")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# orthgonal and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "ortnon", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# orthogonal and smooth
Bhat <- cmls(X = Xmat, Y = Ymat, const = "ortsmo")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# orthogonal and smooth and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "ortsmo", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# orthogonal and smooth and periodic
Bhat <- cmls(X = Xmat, Y = Ymat, const = "orsmpe")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# orthogonal and smooth and periodic and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "orsmpe", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
######***###### UNIMODALITY ######***######
# unimodal
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unimod")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unimod", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "uninon")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "uninon", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and periodic
Bhat <- cmls(X = Xmat, Y = Ymat, const = "uniper")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and periodic and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "uniper", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and periodic and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unpeno")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and periodic and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unpeno", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
######***###### UNIMODALITY AND SMOOTHNESS ######***######
# unimodal and smooth
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unismo")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and smooth and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unismo", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and smooth and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unsmno")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and smooth and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unsmno", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and smooth and periodic
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unsmpe")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and smooth and periodic and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unsmpe", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and smooth and periodic and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unsmpn")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# unimodal and smooth and periodic and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "unsmpn", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
######***###### MONOTONICITY ######***######
# make B
x <- 1:m
Bmat <- rbind(1 / (1 + exp(-(x - quantile(x, 0.5)))),
1 / (1 + exp(-(x - quantile(x, 0.8)))))
struc <- rbind(rep(c(FALSE, TRUE), c(1 * m, 3 * m) / 4),
rep(c(FALSE, TRUE), c(m, m) / 2))
Bmat <- Bmat * struc
# make noisy data
set.seed(1)
Ymat <- Xmat %*% Bmat + rnorm(m*n, sd = 0.25)
# monotonic increasing
Bhat <- cmls(X = Xmat, Y = Ymat, const = "moninc")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# monotonic increasing and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "moninc", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# monotonic increasing and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "monnon")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# monotonic increasing and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "monnon", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# monotonic increasing and smooth
Bhat <- cmls(X = Xmat, Y = Ymat, const = "monsmo")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# monotonic increasing and smooth and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "monsmo", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# monotonic increasing and smooth and non-negative
Bhat <- cmls(X = Xmat, Y = Ymat, const = "mosmno")
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
# monotonic increasing and smooth and non-negative and structured
Bhat <- cmls(X = Xmat, Y = Ymat, const = "mosmno", struc = struc)
mean((Bhat - Bmat)^2)
attr(Bhat, "df")
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