One of the most challenging aspects of molecular modeling is navigating large data associated with molecular conformations—especially when selecting or filtering conformations based on specific criteria. Thankfully, SAMSON’s Node Specification Language (NSL) offers tools for precisely this kind of task. In this post, we’ll focus on the ‘conformation’ attribute space and provide you with a practical introduction to efficiently filter molecular conformations by leveraging its key attributes, such as numberOfAtoms, selected, and selectionFlag.
Why Use Conformation Filters?
Let’s imagine you’re working on a molecular system with hundreds or thousands of conformations and need to identify subsets for analysis or optimization. Without robust filtering options, manually identifying the right conformations can be highly inefficient and error-prone. The conformation attribute space in SAMSON allows you to write simple queries that can target specific properties of conformations, freeing time to focus on the science rather than data wrangling.
Overview of Key Attributes
The conformation attribute space includes several attributes inherited from the general node attributes, as well as attributes unique to conformations. Let’s explore two of these key attributes:
1. numberOfAtoms (Short name: co.nat)
This attribute allows you to filter conformations based on the number of atoms they contain. Whether you’re targeting very small or very large conformations, this feature helps isolate what you need. It supports conditions such as equalities, inequalities, and range-based filtering.
Examples:
co.nat > 100: Matches all conformations with more than 100 atoms.co.nat 100:200: Matches all conformations with atom counts between 100 and 200.
Hands-free browsing through your complex molecular datasets becomes easier with well-constructed queries like these.
2. selected and selectionFlag
Inherited from nodes, the selected attribute (no short name available) and its companion, selectionFlag (short name: sf), provide filtering functionality based on logical selection states.
For example:
co.selected: Matches conformations that are currently selected.not co.selected: Matches conformations that are not selected.co.sf false: Matches conformations where the selection flag isfalse.
These attributes are particularly useful when working iteratively—first selecting conformations meeting certain criteria as part of workflows and then narrowing focus further.
Step Into Practical Examples
Imagine you’re working on a molecular docking project involving conformations for a small organic molecule. Your dataset contains conformations with varying atom counts, and you want to filter those that:
- Have between 50 and 150 atoms.
- Are currently flagged as not selected.
By combining the attributes above, you could write:
|
1 |
co.nat 50:150 and not co.selected |
This query isolates the subset you need instantly, saving hours of manual work.
Where to Start?
Getting started is simple. Refer to the SAMSON documentation for detailed guidelines, and practice writing small queries to test out its capabilities. With time, you’ll find these tools indispensable for tackling various challenges in molecular modeling.
To learn more about the conformation attribute space and its attributes, visit the original documentation page.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get started by downloading SAMSON at https://www.samson-connect.net.