In-place assignment on subviews of bands

[miromarszal]

I was wondering what is the recommended way to modify subviews of a band. My first naive try, which perhaps shows that I don't know that much about how array indexing works in julia, was the following:

B = BandedMatrix{Float64}(undef, 5, 5, 0, 0)
B[band(0)] .= 1.0
B

5×5 BandedMatrix{Float64} with bandwidths (0, 0):
 1.0   ⋅    ⋅    ⋅    ⋅ 
  ⋅   1.0   ⋅    ⋅    ⋅ 
  ⋅    ⋅   1.0   ⋅    ⋅ 
  ⋅    ⋅    ⋅   1.0   ⋅ 
  ⋅    ⋅    ⋅    ⋅   1.0

B[band(0)][2:end-1] .= -1.0

 1.0   ⋅    ⋅    ⋅    ⋅ 
  ⋅   1.0   ⋅    ⋅    ⋅ 
  ⋅    ⋅   1.0   ⋅    ⋅ 
  ⋅    ⋅    ⋅   1.0   ⋅ 
  ⋅    ⋅    ⋅    ⋅   1.0

I can get this to work this way though:

view(B, band(0))[2:end-1] .= -1.0

 1.0    ⋅     ⋅     ⋅    ⋅ 
  ⋅   -1.0    ⋅     ⋅    ⋅ 
  ⋅     ⋅   -1.0    ⋅    ⋅ 
  ⋅     ⋅     ⋅   -1.0   ⋅ 
  ⋅     ⋅     ⋅     ⋅   1.0

which seems a bit verbose to me. Is there some shortcut I'm missing? Actually, I think being able to do the following would be very nice:

B[band(0), 2:end-1] .= -1.0

[jishnub]

You may use

julia> @views B[band(0)][2:end-1] .= -1.0
3-element view(reshape(::BandedMatrix{Float64, Matrix{Float64}, Base.OneTo{Int64}}, 25), [7, 13, 19]) with eltype Float64:
 -1.0
 -1.0
 -1.0

julia> B
5×5 BandedMatrix{Float64} with bandwidths (0, 0):
 1.0    ⋅     ⋅     ⋅    ⋅ 
  ⋅   -1.0    ⋅     ⋅    ⋅ 
  ⋅     ⋅   -1.0    ⋅    ⋅ 
  ⋅     ⋅     ⋅   -1.0   ⋅ 
  ⋅     ⋅     ⋅     ⋅   1.0