improve and simplify [h/v]cat

Author: dkarrasch

src/blockmap.jl

@@ -84,17 +84,13 @@ function Base.hcat(As::Union{LinearMap, UniformScaling, AbstractVecOrMat}...)
     T = promote_type(map(eltype, As)...)
     nbc = length(As)
 
-    nrows = -1
     # find first non-UniformScaling to detect number of rows
-    for A in As
-        if !(A isa UniformScaling)
-            nrows = size(A, 1)
-            break
-        end
-    end
-    @assert nrows != -1
+    j = findfirst(x -> !isa(x, UniformScaling), As)
     # this should not happen, function should only be called with at least one LinearMap
-    return BlockMap{T}(promote_to_lmaps(ntuple(i->nrows, nbc), 1, 1, As...), (nbc,))
+    @assert !isnothing(j)
+    nrows = size(As[j], 1)
+    
+    return BlockMap{T}(promote_to_lmaps(ntuple(_ -> nrows, Val(nbc)), 1, 1, As...), (nbc,))
 end
 
 ############
@@ -126,18 +122,14 @@ function Base.vcat(As::Union{LinearMap,UniformScaling,AbstractVecOrMat}...)
     T = promote_type(map(eltype, As)...)
     nbr = length(As)
 
-    ncols = -1
-    # find first non-UniformScaling to detect number of columns
-    for A in As
-        if !(A isa UniformScaling)
-            ncols = size(A, 2)
-            break
-        end
-    end
-    @assert ncols != -1
+    # find first non-UniformScaling to detect number of rows
+    j = findfirst(x -> !isa(x, UniformScaling), As)
     # this should not happen, function should only be called with at least one LinearMap
-    rows = ntuple(i->1, nbr)
-    return BlockMap{T}(promote_to_lmaps(ntuple(i->ncols, nbr), 1, 2, As...), rows)
+    @assert !isnothing(j)
+    ncols = size(As[j], 2)
+
+    rows = ntuple(i->1, Val(nbr))
+    return BlockMap{T}(promote_to_lmaps(ntuple(_ -> ncols, Val(nbr)), 1, 2, As...), rows)
 end
 
 ############