[R] MDS: Sample in one group appears twice. Why?

[A Ezhil]

Hi All,

I am trying to apply MDS for 4 groups in my data. The
groups are:  

groups = list( Day1C=c(9), Day1T=c(7,8,10),
Day2C=c(1,2,3,6,11,13,14,15), Day2T=c(4,5,12,16,17,18)
)

When I do the MDS plot the group1 member appears twice
instead of one time in the plot. I don't know why this
is happening.

I would greatly appreciate your help in fixing this
problem.

Thanks in Advance.
Ezhil