How do I programmatically get a list of packages from apt?

Question

How can I use Python/python-apt to programmatically get the same result as "dpkg --get-selections"?

Answer 1

To display the first five packages:

import apt_pkg

apt_pkg.init()
cache = apt_pkg.Cache()

i = 5
for pkg in cache.Packages:
  print(pkg)
  i -= 1
  if i < 0:
    break

The output (when run on my Ubuntu system):

$ python apt_package_list.py
Reading package lists... Done
Building dependency tree       
Reading state information... Done
<apt_pkg.Package object: name:'tesseract-ocr-epo' section: 'universe/graphics' id:48834>
<apt_pkg.Package object: name:'omninotify' section: '' id:48674>
<apt_pkg.Package object: name:'pipenightdreams' section: 'universe/games' id:43500>
<apt_pkg.Package object: name:'mumudvb' section: 'universe/misc' id:41568>
<apt_pkg.Package object: name:'mpg123-alsa' section: '' id:41448>
<apt_pkg.Package object: name:'tbb-examples' section: 'universe/doc' id:38301>