[R] Problems with principal components analysis PCA with prcomp

[Carlos Guerra]

Dear friends,

I am beginning to use R software in my academic research and I'm having some
problems regarding the use of PCA.
I have a table with 24445 rows and 9 columns, and I used the function
prcomp() to do the analysis.
Working with an example…:

x<-read.table("test.txt", header=T)
row.names(x)<-x[,1]
x<-x[,-1]
require(stats)
pca<-prcomp(x, scale=T)
names(pca)

## here begin my problems… know what…??##

My questions are:
1. How can I group my samples (rows) in a graphical way?
2. How can I extract the samples related to each group? …or… How can I
create a new column with "n" values corresponding to each group created?
3. Is it possible to extract/export the information in an object into a file
with a dbf extension (e.g. test.dbf)?

Best regards,
Carlos

+++++++++++++++++++++++++++++++
Carlos GUERRA

Instituto Politécnico de Viana do Castelo
Escola Superior Agrária de Ponte de Lima

Mosteiro de Refóios do Lima
4990-706 Ponte de Lima
PORTUGAL

MAIL: carlosguerra at esa.ipvc.pt
TEL: +351 912 407 109
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FID	ALTIM	TEMP	CLI	FAS
0	14	4	1	2
1	65	1	1	3
2	54	1	7	1
3	112	1	5	1
4	117	4	2	1
5	180	2	1	2
6	54	4	1	3
7	125	4	1	2
8	217	4	2	2
9	171	3	2	2
10	37	4	3	3
11	114	2	4	3
12	229	4	4	3
13	286	3	3	3
14	227	3	5	3
15	16	4	5	2
16	74	4	5	2
17	89	4	6	1
18	98	2	5	1
19	64	2	4	2
20	96	2	6	1
21	100	4	6	3
22	147	4	7	1
23	196	4	7	3
24	282	3	1	3
25	308	3	1	3