triSht

\(x\) coordinates of the triangulation nodes

\(y\) coordinates of the triangulation nodes

Matrix of indices which defines the triangulation,
 each row corresponds to a triangle.
Columns <code>i1</code>, <code>i2</code>, <code>i3</code> of the row \(i\) contain
 the node indices defining the \(i\)th triangle.
Columns <code>j1</code>, <code>j2</code>, <code>j3</code> of the row \(i\) contain
 the indices of neighbour triangles (or 0 if no neighbour available
 along the convex hull).
Columns <code>k1</code>, <code>k2</code>, <code>k3</code> of the row \(i\) contain
 the indices of the arcs of the \(i\)th triangle as returned by the
 <code><a rd-options="" href="/link/arcs?package=interp&version=1.0-33" data-mini-rdoc="interp::arcs">arcs</a></code> function.

trlist

Matrix describing the circumcircles and triangles.
Columns <code>x</code> and <code>y</code> contain coordinates of the
 circumcircle centers, <code>r</code> is the circumcircle radius.
<code>area</code> is the triangle area and <code>ratio</code> is the ratio of
 the radius of the inscribed circle to the circumcircle radius. It
 takes it maximum value 0.5 for an equilateral triangle.
The radius of the inscribed circle can be get via
 \(r_i=\frac{r}{ratio}\).

cclist

number of points on the convex hull

nchull

A vector containing the indices of nodes forming the convec hull (in
 counterclockwise ordering).

chull

number of arcs forming the triangulation

narcs

A matrix with node indices describing the arcs, contains
 two columns <code>from</code> and <code>to</code>.

arcs

call

R object that represents the triangulation of a set of 2D points,
 generated by <code><a rd-options="" href="/link/tri.mesh?package=interp&version=1.0-33" data-mini-rdoc="interp::tri.mesh">tri.mesh</a></code>.

spatial

Bivariate data interpolation on regular and irregular
grids, either linear or using splines are the main part of this
package.  It is intended to provide FOSS replacement functions for
the ACM licensed akima::interp and tripack::tri.mesh functions.
Currently the piecewise linear interpolation part of akima::interp
(and also akima::interpp) is implemented in interp::interp, this
corresponds to the call akima::interp(..., linear=TRUE) which is the
default setting and covers most of akima::interp use cases in
depending packages.  A re-implementation of Akimas spline
interpolation (akima::interp(..., linear=FALSE)) is currently under
development and will complete this package in a later
version. Estimators for partial derivatives are already available,
these are a prerequisite for the spline interpolation.  The basic
part is currently a GPLed triangulation algorithm (sweep hull
algorithm by David Sinclair) providing the starting point for the
piecewise linear interpolator. As side effect this algorithm is also
used to provide replacements for the basic functions of the tripack
package which also suffer from the ACM restrictions.  All functions
are designed to be backward compatible with their akima / tripack
counterparts.

Fortran code by R J Renka R functions by Albrecht Gebhardt  With contributions from Stephen Eglen stephenancedacuk

interp

Interpolation Methods

Albrecht Gebhardt

Roger Bivand

David Sinclair

triSht function

Matrix of indices which defines the triangulation,
 each row corresponds to a triangle.
Columns <code>i1</code>, <code>i2</code>, <code>i3</code> of the row \(i\) contain
 the node indices defining the \(i\)th triangle.
Columns <code>j1</code>, <code>j2</code>, <code>j3</code> of the row \(i\) contain
 the indices of neighbour triangles (or 0 if no neighbour available
 along the convex hull).
Columns <code>k1</code>, <code>k2</code>, <code>k3</code> of the row \(i\) contain
 the indices of the arcs of the \(i\)th triangle as returned by the
 <code><a rd-options='' href='arcs'>arcs</a></code> function.

R object that represents the triangulation of a set of 2D points,
 generated by <code><a rd-options='' href='tri.mesh'>tri.mesh</a></code>.

triSht: A triangulation object

Description

Arguments

See Also