Assignment Branch Condition

method.rb

# Get Catalogue Sections
# Returns 3 arrays of resource objects (frontmatter, catalogue, backmatter)
def catalogue_sections
  contents    = sort_catalogue_contents
  frontmatter = contents.find_all { |p| p.data.sort_order <= 10 }
  backmatter  = contents.find_all { |p| p.data.sort_order > 100 }
  catalogue   = contents.find_all do |p|
    p.data.sort_order > 10 && p.data.sort_order <= 100
  end

  frontmatter.sort_by! { |p| p.data.sort_order }
  catalogue.sort_by! { |p| p.data.sort_order }
  backmatter.sort_by! { |p| p.data.sort_order }

  return frontmatter, catalogue, backmatter
end

I'm writing a Helper Method in the Middleman static site generator.
I've started using Rubocop in an attempt to write higher-quality code, and I keep getting the following warning:

Assignment Branch Condition size for catalogue_sections is too high. [25.34/15]

Can anyone explain (in non-computer science jargon) what this actually means?

It means that your method is too big, that it's doing too much. In this case one could argue that it contains too much duplication.

A bit computer sciency, but here's the definition: http://c2.com/cgi/wiki?AbcMetric