Begin modifications for beta profiles

src/MixedModels.jl

@@ -87,5 +87,6 @@ include("pls.jl")
 include("simulate.jl")
 include("PIRLS.jl")
 include("mixedmodel.jl")
+include("profile.jl")
 
 end # module

src/modelterms.jl

@@ -30,6 +30,12 @@ function reweight!(A::MatrixTerm{T}, sqrtwts::Vector{T}) where T
     A
 end
 
+function dropcolumn(A::MatrixTerm, i::Integer)
+    n, p = size(A)
+    inds = deleteat!(collect(1:p), i)
+    MatrixTerm(A.x[:, inds], A.cnames[inds])
+end
+
 eltype(A::MatrixTerm) = eltype(A.wtx)
 
 Base.size(A::MatrixTerm) = size(A.wtx)

src/profile.jl

@@ -0,0 +1,20 @@
+"""
+    dropXcolumn!(m::LinearMixedModel, i::Integer)
+
+Return `m` with column `i` of the fixed-effects model matrix, `X`, dropped
+
+This operation changes dimensions of some blocks in `m.A` and `m.L`
+FIXME: It looks as if A and L need to be generated anew.
+"""
+function dropXcolumn!(m::LinearMixedModel, i::Integer)
+    trms = m.trms
+    xpos = length(trms) - 1
+    xtrm = trms[xpos] = reweight!(dropcolumn(trms[xpos], i), m.sqrtwts)
+    for j in 1:xpos
+        Axj = m.A[Block(xpos, j)] = xtrm'trms[j]
+        m.L[Block(xpos, j)] = deepcopy(Axj)
+    end
+    Axp1x = m.A[Block(xpos + 1, xpos)] = trms[xpos + 1]'xtrm
+    m.L[Block(xpos + 1, xpos)] = deepcopy(Axp1x)
+    m
+end