Information Technology Reference
In-Depth Information
Orthogonal parallel translation is incorporated in several of the functions available in
UBbipl
. The two arguments
orthog.transx
and
orthog.transy
regulate the amount
of orthogonal parallel translation in a horizontal and vertical direction, respectively. The
argument
reflect
allows reflection about the x- and y-axes. Figure 2.12 is constructed
by the following call to function
PCAbipl
.
PCAbipl(X = aircraft.data[,2:5], pch.samples = 15,
pch.samples.size = 1.2, colours = "green", orthog.transx =
rep(1.75, 4), orthog.transy = rep(-4,4), rotate.degrees = 180,
offset = c(1.3, 0.5, 0.3, 0.5), n.int = c(5,3,5,3),
pos.m = c(1,4,4,4), offset.m = rep(-0.2, 4))
With two axes in two dimensions we would normally arrange that the origin corresponds
to simple values on both variables. With
p
axes in
r
p
dimensions, this cannot be done
for all variables, but we may ensure that the new origin corresponds to simple values
on
r
of the axes. This has been done in Figure 2.13, where the origin has been chosen
<
SLF
RGF
6
6
5
4
5
3
r
c
j
2
q
p
k
m
4
u
g
v
i
h
1
t
n
d
f
e
s
w
0
0
0.2
b
a
2
4
6
8
0.3
10
SPR
12
PLF
Figure 2.13
The biplot of the aircraft data with orthogonal parallel translation of the
axes, where the origin has been chosen as
SPR
=
0and
SLF
=
0.
