Readme file
SERIES C
 Applied Statistics
Principal component analysis of landmarks from reversible images,
by C.M. Theobald et al.
Journal of the Royal Statistical Society,
Series C, Applied Statistics, Volume
53 (2004) part 1, 163-175
The file carrotcoords.txt is an ASCII file containing the data used
in Section 3.1 of the paper.
The columns include a header, and there is one row for each of the
660 carrots.
The columns contain vertical and horizontal coordinates of landmarks
on the boundaries of outlines of halved carrots, which were rotated
so that each major axis was vertical, and were measured relative to
the centroid of the outlines.
The analysis described in the final paragraph of Section 3.1 of the
paper is based on the following 12 coordinates. They are defined assuming
that the axis of the digitizer is vertical with the crown end of each
carrot at the top, and that horizontal coordinates are measured in a
common direction with the major axis at zero.
y4 vertical coordinate of the bottom-most position of the boundary
yl0 vertical coordinate of the left shoulder
yr0 vertical coordinate of the right shoulder
xl0 horizontal coordinate of the left shoulder
xl1 horizontal coordinate of the left boundary one quarter of the way
from the midpoint of the shoulders to the bottom
xl2 horizontal coordinate of the left boundary one half of the way
from the midpoint of the shoulders to the bottom
xl3 horizontal coordinate of the left boundary three quarters of the
way from the midpoint of the shoulders to the bottom
xr0, xr1, xr2, xr3 are defined similarly to xl0, xl1, xl2, xl3, but
'right' replaces 'left'.
x4 horizontal coordinate of the bottom-most position
The analysis shown in Table 1 of the paper uses the same vertical coordinates
as above, but the horizontal coordinates are adjusted so that the vertical
axis goes through the bottom-most position and the mid-point of the
left and right shoulders. The adjusted coordinates are labeled axl0
etc. Thus x4 is adjusted to zero (and ax4 is therefore omitted); also
axl0 and axr0 sum to zero.
Chris Theobald
Biomathematics and Statistics Scotland
James Clerk Maxwell Building
The King's Buildings
Edinburgh
EH9 3JZ
UK
E-mail cmt@bioss.ac.uk
|
