Struct chemfiles::Selection

pub struct Selection { /* private fields */ }

A Selection allow to select atoms in a Frame, from a selection language. The selection language is built by combining basic operations. Each basic operation follows the <selector>[(<variable>)] <operator> <value> structure, where <operator> is a comparison operator in == != < <= > >=.

Implementations

impl Selection

pub fn new<'a, S: Into<&'a str>>(selection: S) -> Result<Selection, Error>

Create a new selection from the given selection string.

Errors

This function fails if the selection string is invalid.

Example

let selection = Selection::new("pairs: name(#1) H and name(#2) O").unwrap();

pub fn size(&self) -> usize

Get the size of the selection, i.e. the number of atoms we are selecting together.

This value is 1 for the ‘atom’ context, 2 for the ‘pair’ and ‘bond’ context, 3 for the ‘three’ and ‘angles’ context and 4 for the ‘four’ and ‘dihedral’ context.

Example

let selection = Selection::new("pairs: name(#1) H and name(#2) O").unwrap();
assert_eq!(selection.size(), 2);

pub fn string(&self) -> String

Get the selection string used to create this selection.

Example

let selection = Selection::new("name H").unwrap();
assert_eq!(selection.string(), "name H");

pub fn evaluate(&mut self, frame: &Frame) -> Vec<Match>

Evaluate a selection for a given frame, and return the corresponding matches.

Example

let mut frame = Frame::new();
frame.add_atom(&Atom::new("H"), [1.0, 0.0, 0.0], None);
frame.add_atom(&Atom::new("O"), [0.0, 0.0, 0.0], None);
frame.add_atom(&Atom::new("H"), [-1.0, 0.0, 0.0], None);

let mut selection = Selection::new("pairs: name(#1) H and name(#2) O").unwrap();
let matches = selection.evaluate(&frame);

assert_eq!(matches.len(), 2);

assert_eq!(matches[0].len(), 2);
assert_eq!(matches[0][0], 0);
assert_eq!(matches[0][1], 1);

assert_eq!(matches[1].len(), 2);
assert_eq!(matches[1][0], 2);
assert_eq!(matches[1][1], 1);

pub fn list(&mut self, frame: &Frame) -> Vec<usize>

Evaluates a selection of size 1 on a given frame. This function returns the list of atomic indexes in the frame matching this selection.

Panics

If the selection size is not 1

Example

let mut frame = Frame::new();
frame.add_atom(&Atom::new("H"), [1.0, 0.0, 0.0], None);
frame.add_atom(&Atom::new("O"), [0.0, 0.0, 0.0], None);
frame.add_atom(&Atom::new("H"), [-1.0, 0.0, 0.0], None);

let mut selection = Selection::new("name H").unwrap();
let matches = selection.list(&frame);

assert_eq!(matches.len(), 2);
assert_eq!(matches[0], 0);
assert_eq!(matches[1], 2);

Trait Implementations

impl Clone for Selection

fn clone(&self) -> Selection

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Selection

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for Selection

fn drop(&mut self)

Executes the destructor for this type.