cmap {bio3d} | R Documentation |
Construct a Contact Map for a Given Protein Structure.
cmap(xyz, grpby=NULL, dcut = 4, scut = 3, mask.lower = TRUE)
xyz |
numeric vector of xyz coordinates. |
grpby |
a vector counting connective duplicated elements that
indicate the elements of xyz that should be considered as a group
(e.g. atoms from a particular residue). |
dcut |
a cuttoff distance value below which atoms are considered in contact. |
scut |
a cuttoff neighbour value which has the effect of excluding atoms that are sequentially within this value. |
mask.lower |
logical, if TRUE the lower matrix elements (i.e. those below the diagonal) are returned as NA. |
A contact map is a simplified distance matrix. See the distance matrix
function dm
for further details.
Returns a N by N numeric matrix composed of zeros and ones, where one indicates a contact between selected atoms.
Barry Grant
Grant, B.J. et al. (2006) Bioinformatics 22, 2695–2696.
##- Read PDB and Traj files pdb <- read.pdb( system.file("examples/hivp.pdb", package="bio3d") ) ##trj <- read.dcd( system.file("examples/hivp.dcd", package="bio3d") ) ## Atom Selection indices inds <- atom.select(pdb, "calpha") ## Reference contact map ref.cont <- cmap( pdb$xyz[inds$xyz], dcut=6, scut=3 ) plot.dmat(ref.cont) ## Not run: ## For each frame of trajectory sum.cont <- NULL for(i in 1:nrow(trj)) { ## Contact map for frame 'i' cont <- cmap(trj[i,inds$xyz], dcut=6, scut=3) ## Product with reference prod.cont <- ref.cont * cont sum.cont <- c(sum.cont, sum(prod.cont,na.rm=TRUE)) } plot(sum.cont, typ="l") ## End(Not run)