[R] loadings matrices in plsr vs pcr in pls pacakage

[Roy Little]

Dear list,
I have a question concerning the above mentioned methods in the pls 
package with respect to the loadings matrix produced by the call. In 
some work I am doing I have found that the values produced are nearly of 
the same magnitude but of opposite sign. When I use the example data 
(sensory) I find this result reproduced. I am prepared to work this 
through but I have a feeling that there could be a possible error in the 
code. (?!)



 > sens.pcr$loadings
            Comp 1      Comp 2     Comp 3    Comp 4
yellow  75.186621  -0.4780473   3.212149  1.750123
green  -90.490256   8.5880530   1.634961  1.042239
brown   -2.861241 -11.3600509 -15.920789 -1.105799
glossy  13.347090  19.3103902  -3.121693  2.781282
transp  20.126987  24.0653312  -6.656764 -1.842907
syrup   -7.199972  -5.3436196  -5.073675  5.620454
 > sens.pls$loadings

Loadings:
        Comp 1  Comp 2  Comp 3  Comp 4
yellow -74.448 -10.519   3.169  -1.056
green   88.299  21.627  -0.521  -0.976
brown    4.959 -14.253 -12.761  -0.371
glossy -15.798  15.914  -7.574   3.504
transp -23.049  18.673 -12.214  -2.068
syrup    8.045  -5.313  -3.698   2.181

Thank you for your help.

Roy Little
Dept. Chem.
Facultad de Ciencias
Universidad de los Andes
Mérida, Venezuela