Efficiently Selecting Folders by Atom and Molecule Counts in SAMSON

When working with complex molecular models, navigating and organizing large datasets can feel overwhelming. For molecular modelers using SAMSON, one common challenge is finding folders that match specific criteria, such as the number of atoms, molecules, or specific types of atoms like carbons or hydrogens. The Node Specification Language (NSL) in SAMSON offers an elegant solution through its attribute-based filtering system for folder nodes. In this post, we’ll explore how you can use these attributes to streamline your molecular modeling workflow.

Why Filter by Atom and Molecule Counts?

Imagine you’re working on a protein model with thousands of folders, and each folder represents a different structural scenario. You might want to quickly identify folders meeting specific criteria, such as:

  • Containing a certain range of atoms, molecules, or chains.
  • Having a limited number of specific atoms, such as carbon, hydrogen, or oxygen.
  • Matching structural groups or segment counts.

This is where NSL’s folder attributes, like f.nat (number of atoms), f.nm (number of molecules), and f.nC (number of carbons), become incredibly useful. They allow you to express queries that fetch exactly the data you need, saving time and effort.

How to Use Folder Number Attributes: Practical Examples

SAMSON allows you to define filters using the NSL and target specific folder characteristics. Below are some of the key attributes:

1. numberOfAtoms (f.nat)

This specifies the number of atoms in a folder. For example:

  • folder.nat > 100 (or f.nat > 100): Finds folders with more than 100 atoms.
  • folder.nat 100:200 (or f.nat 100:200): Finds folders with 100–200 atoms.

2. numberOfMolecules (f.nm)

Targets folders containing specific numbers of molecules:

  • folder.nm < 3: Finds folders with less than 3 molecules.
  • folder.nm 2:5: Finds folders with a molecule count between 2 and 5.

3. Filtering Specific Atom Types

Additional number attributes allow you to filter based on specific atom types:

  • numberOfCarbons (f.nC) to filter by carbon atom count.
  • numberOfHydrogens (f.nH) to filter by hydrogen atom count.
  • numberOfOxygens (f.nO) to filter by oxygen atom count.

For example, f.nH > 10 finds folders with more than 10 hydrogens, while f.nO 5:15 targets folders containing between 5 and 15 oxygen atoms.

4. Segment and Chain Counts

Working with structural models often involves querying based on chains and segments. These attributes help:

  • numberOfChains (f.nc): Filters by chain count. E.g., f.nc < 3 looks for folders with fewer than 3 chains.
  • numberOfSegments (f.ns): Filters folders based on segment count. For instance, f.ns 2:4 finds folders with 2–4 segments.

Example Workflow

Let’s say you’re modeling a complex molecule and need to identify folders containing more than 100 atoms but fewer than 5 molecules. Here’s how you could express this using NSL:

  • f.nat > 100 && f.nm < 5

This single-line query eliminates manually sifting through folders and gives you the exact datasets you need in a fraction of the time.

Closing Thoughts

The ability to filter folders in SAMSON based on specific numerical attributes is a powerful tool for molecular modelers. By leveraging attributes such as f.nat, f.nm, and f.nC, you can quickly pinpoint the datasets you need and maintain focus on the scientific challenges at hand.

To learn more, see the full documentation at Folder Attributes Documentation.

SAMSON and all SAMSON Extensions are free for non-commercial use. Get it today at https://www.samson-connect.net.

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