Avoid vcat

hw2.jl

# Esta opción es suficiente para pasar el ejercicio,
# pero abajo hay una opción aún más rápida

function remove_in_each_row_no_vcat(img, column_numbers)
	@assert size(img, 1) == length(column_numbers) # same as the number of rows
	m, n = size(img)
	local img′ = similar(img, m, n-1) # create a similar image with one less column

	for (i, j) in enumerate(column_numbers)
		# EDIT THE FOLLOWING LINE and split it into two lines
		# to avoid using `vcat`.
		img′[i, 1:j-1] .= img[i, 1:j-1]
		img′[i, j:end] .= img[i, j+1:end]
	end
	img′
end

# Esta opción es todavía más rápida, utiliza el macro @view
# @view evita hacer una copia del vector.

function remove_in_each_row_no_vcat(img, column_numbers)
	@assert size(img, 1) == length(column_numbers) # same as the number of rows
	m, n = size(img)
	local img′ = similar(img, m, n-1) # create a similar image with one less column

	for (i, j) in enumerate(column_numbers)
		# EDIT THE FOLLOWING LINE and split it into two lines
		# to avoid using `vcat`.
		img′[i, 1:j-1] .= @view img[i, 1:j-1]
		img′[i, j:end] .= @view img[i, j+1:end]
	end
	img′
end