conect: Create ‘conect’ Object

Description

Creates an object of class ‘conect’ containing the IDs of bonded atoms defining the connectivity of a molecular system.

Usage

conect(...)
# S3 method for default
conect(eleid.1, eleid.2, ...)
# S3 method for coords
conect(x, radii = 0.75, safety = 1.2, by.block = FALSE, ...)
# S3 method for pdb
conect(x, safety = 1.2, by.block = FALSE, ...)
is.conect(x)

Value

conect returns a two-column data.frame of class ‘conect’ whose rows contain the IDs of bonded atoms. The columns of this data.frame are described below:

eleid.1: a integer vector containing the elements IDs defining the connectivity of the system.
eleid.2: a integer vector containing the elements IDs defining the connectivity of the system.

is.conect returns TRUE if x

is an object of class ‘coords’ and FALSE otherwise.

Arguments

...: arguments passed to methods.
eleid.1: a integer vector containing the IDs of bonded atoms.
eleid.2: a integer vector containing the IDs of bonded atoms.
x: an R object containing atomic coordinates.
radii: a numeric vector containing atomic radii used to find neigbours.
safety: a numeric value used to extend the atomic radii.
by.block: a logical value indicating whether the connectivity has to be determine by block (see details).

Details

conect is a generic function to create objects of class ‘conect’. The purpose of this class is to store CONECT records from PDB files, indicating the connectivity of a molecular system.
The default method creates a conect object from its different components, i.e.: eleid.1 and eleid.2. Both arguments have to be specified.
The S3 method for object of class ‘coords’ determine the connectivity from atomic coordinates. A distance matrix is computed, then, for each pair of atom the distance is compared to a bounding distance computed from atomic radii. If this distance is lower than the bounding distance then the atoms are assumed to be connected.
The S3 method for object of class ‘pdb’ first use element names to search for atomic radii in the elements data set. Then atomic coordinates and radii are passed to conect.coords.
If by.block == TRUE, a grid is defined to determined the connectivity by block. The method is slow but allow to deal with very large systems.
is.conect tests if an object of class ‘conect’, i.e. if it has a “class” attribute equal to conect.

Examples

Run this code

# If atom 1 is connected to atom 2, 3, 4 and 5
# then we can prepare the following 'conect' object:
x <- conect(rep(1,4), 2:5)
print(x)
is.conect(x)

# Compute conectivity from coordinates
x <- read.pdb(system.file("examples/PCBM_ODCB.pdb", package="Rpdb"), CONECT = FALSE)
x$conect
x$conect <- conect(x)
x$conect