Editing PatternQuery:Principles (section)

==Example, Revised==
Now that we know the basic building blocks of the language, let’s go back to our original example and analyze it:

<syntaxhighlight lang="python">
HetResidues()
  .AmbientAtoms(3.0)
  .Filter(lambda m: m.Count(Atoms('Ca')) >= 1)
</syntaxhighlight>

This corresponds to the following process.

# A generator query <code>[[PatternQuery:Language_Reference#HetResidues | HetResidues()]]</code> is executed that produces a sequence of patterns that are composed of atoms corresponding to HET residues.
# Next, the original sequence is modified by adding atoms within 3 angstrom from any original atom to each pattern.
# Finally, each pattern in the modified sequence is examined: all “calcium atom patterns” are identified and counted. Only these patterns that contain at least 1 Ca atom are kept.

Graphically:

<code>[[PatternQuery:Language_Reference#HetResidues | HetResidues()]]</code>
[[Image:PatternQuery-Principles-HetResidues.png|none|500px]]


<code>[[PatternQuery:Language_Reference#AmbientAtoms | .AmbientAtoms(3)]]</code>
[[Image:PatternQuery-Principles-AmbientAtoms.png|none|500px]]


<code>[[PatternQuery:Language_Reference#Filter | .Filter(lambda l: l.Count(Atoms('Ca')) > 0)]]</code>
[[Image:PatternQuery-Principles-AmbientAtoms-filter.png|none|500px]]