Struct chemfiles::Selection
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pub struct Selection { /* fields omitted */ }
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
== != < <= > >=
.
Methods
impl Selection
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pub fn new<'a, S: Into<&'a str>>(selection: S) -> Result<Selection>
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Create a new selection from the given selection string.
Example
let selection = Selection::new("pairs: name(#1) H and name(#2) O").unwrap();
pub fn size(&self) -> Result<u64>
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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' contextes and 4 for the 'four' and 'dihedral' contextes.
Example
let selection = Selection::new("pairs: name(#1) H and name(#2) O").unwrap(); assert_eq!(selection.size(), Ok(2));
pub fn string(&self) -> Result<String>
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Get the selection string used to create this selection.
Example
let selection = Selection::new("name H").unwrap(); assert_eq!(selection.string(), Ok(String::from("name H")));
pub fn evaluate(&mut self, frame: &Frame) -> Result<Vec<Match>>
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Evaluate a selection for a given frame, and return the corresponding matches.
Example
let mut frame = Frame::new().unwrap(); frame.add_atom(&Atom::new("H").unwrap(), [1.0, 0.0, 0.0], None).unwrap(); frame.add_atom(&Atom::new("O").unwrap(), [0.0, 0.0, 0.0], None).unwrap(); frame.add_atom(&Atom::new("H").unwrap(), [-1.0, 0.0, 0.0], None).unwrap(); let mut selection = Selection::new("pairs: name(#1) H and name(#2) O").unwrap(); let matches = selection.evaluate(&frame).unwrap(); 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) -> Result<Vec<u64>>
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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().unwrap(); frame.add_atom(&Atom::new("H").unwrap(), [1.0, 0.0, 0.0], None).unwrap(); frame.add_atom(&Atom::new("O").unwrap(), [0.0, 0.0, 0.0], None).unwrap(); frame.add_atom(&Atom::new("H").unwrap(), [-1.0, 0.0, 0.0], None).unwrap(); let mut selection = Selection::new("name H").unwrap(); let matches = selection.list(&frame).unwrap(); assert_eq!(matches.len(), 2); assert_eq!(matches[0], 0); assert_eq!(matches[1], 2);
Trait Implementations
impl Clone for Selection
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fn clone(&self) -> Selection
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Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
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Performs copy-assignment from source
. Read more