triangles.RdThis function extracts a list of triangles
from an triangulation object created by tri.mesh.
triangles(tri.obj)object of class triSht
The vertices in the returned matrix (let's denote it with
retval) are ordered counterclockwise. The columns tr\(x\)
and arc\(x\), \(x=1,2,3\) index the triangle and arc, respectively,
which are opposite (not shared by) node node\(x\), with
tri\(x=0\) if arc\(x\) indexes a boundary arc. Vertex indexes
range from 1 to \(n\), the number of nodes, triangle indexes from 0
to \(nt\), and arc indexes from 1 to \(na = nt+n-1\).
A matrix with columns node1, node2, node3,
representing the vertex nodal indexes,
tr1, tr2, tr3, representing neighboring triangle
indexes and arc1, arc2, arc3 reresenting arc
indexes.
Each row represents one triangle.
triSht, print.triSht,
plot.triSht, summary.triSht,
triangles
# use the smallest Franke data set
data(franke)
fr3.tr<-tri.mesh(franke$ds3$x, franke$ds3$y)
triangles(fr3.tr)
#> node1 node2 node3 tr1 tr2 tr3 arc1 arc2 arc3
#> [1,] 1 11 4 2 3 0 1 2 3
#> [2,] 12 4 11 1 7 5 1 4 5
#> [3,] 8 1 4 1 9 0 2 6 7
#> [4,] 10 4 6 5 15 9 8 9 10
#> [5,] 4 12 6 8 4 2 11 8 5
#> [6,] 12 5 16 13 8 7 12 13 14
#> [7,] 5 12 11 2 0 6 4 15 14
#> [8,] 12 16 6 11 5 6 16 11 13
#> [9,] 10 8 4 3 4 14 6 10 17
#> [10,] 13 3 6 15 18 24 18 19 20
#> [11,] 21 6 16 8 17 18 16 21 22
#> [12,] 16 22 17 19 17 13 23 24 25
#> [13,] 22 16 5 6 20 12 12 26 25
#> [14,] 3 8 10 9 15 23 17 27 28
#> [15,] 6 3 10 14 4 10 27 9 18
#> [16,] 15 21 17 17 22 21 29 30 31
#> [17,] 16 17 21 16 11 12 29 21 24
#> [18,] 13 6 21 11 21 10 22 32 19
#> [19,] 19 17 22 12 31 28 23 33 34
#> [20,] 25 22 5 13 30 31 26 35 36
#> [21,] 15 13 21 18 16 26 32 31 37
#> [22,] 17 23 15 27 16 28 38 30 39
#> [23,] 2 8 3 14 34 0 28 40 41
#> [24,] 9 3 13 10 25 34 20 42 43
#> [25,] 9 13 14 26 35 24 44 45 42
#> [26,] 13 15 14 32 25 21 46 44 37
#> [27,] 15 23 18 39 32 22 47 48 38
#> [28,] 19 23 17 22 19 33 39 34 49
#> [29,] 25 7 19 40 31 30 50 51 52
#> [30,] 7 25 5 20 0 29 35 53 52
#> [31,] 19 22 25 20 29 19 36 51 33
#> [32,] 15 18 14 36 26 27 54 46 48
#> [33,] 24 23 19 28 40 39 49 55 56
#> [34,] 9 2 3 23 24 0 40 43 57
#> [35,] 14 20 9 38 25 36 58 45 59
#> [36,] 14 18 20 37 35 32 60 59 54
#> [37,] 18 24 20 38 36 39 61 60 62
#> [38,] 24 9 20 35 37 0 58 61 63
#> [39,] 24 18 23 27 33 37 47 56 62
#> [40,] 24 19 7 29 0 33 50 64 55