R help - Jun 2007 - Condensed PCA Results

Hello all,


I'm currently using R to do PCA Analysis, and was wondering if anyone knew
the
specific R Code that could limit the output of the PCA Analysis so that you
only get the Principal Component features as your output and none of the
extraneous words or numbers that you don't want.

If that was unclear, let me use linear regression as an example:

"lm(y~x)" is the normal command for linear regression, but it produces
other
text and string aside from the regression coefficients.

"lm(y~x)$coefficients" gives you just the regression coefficients when
you carry
out the command.


When I carry out PCA on R, typically I get:


Standard deviations:
[1] 83.732400 14.212402  6.489426  2.4827900

Rotation:
                PC1         PC2         PC3         PC4
Murder   0.04170432 -0.04482166  0.07989066 -0.99492173
Assault  0.99522128 -0.05876003 -0.06756974  0.03893830
UrbanPop 0.04633575  0.97685748 -0.20054629 -0.05816914
Rape     0.07515550  0.20071807  0.97408059  0.07232502


I want to get only:

                PC1         PC2         PC3         PC4
Murder   0.04170432 -0.04482166  0.07989066 -0.99492173
Assault  0.99522128 -0.05876003 -0.06756974  0.03893830
UrbanPop 0.04633575  0.97685748 -0.20054629 -0.05816914
Rape     0.07515550  0.20071807  0.97408059  0.07232502


I want to be able to do this because I am actually carrying out PCA in RExcel. 
I am able to do the PCA analysis using the "prcomp(data)" and
"GetArray"
commands, but doing that puts all of the aforementinoed output in a single row
of cells instead of assigning each word and number its own individual cell.

I figured this dealt more with R code than Excel, so I decided to post it here.

Can anyone help me out?  Is there a command that can carry out what I've
mentioned?


Wayne

if x is your matrix, then
prcomp(x)$rotation
gets you what you want

Katharina

Wayne Aldo Gavioli schrieb:
> Hello all,
>
>
> I'm currently using R to do PCA Analysis, and was wondering if anyone
knew the
> specific R Code that could limit the output of the PCA Analysis so that you
> only get the Principal Component features as your output and none of the
> extraneous words or numbers that you don't want.
>
> If that was unclear, let me use linear regression as an example:
>
> "lm(y~x)" is the normal command for linear regression, but it
produces other
> text and string aside from the regression coefficients.
>
> "lm(y~x)$coefficients" gives you just the regression coefficients
when you carry
> out the command.
>
>
> When I carry out PCA on R, typically I get:
>
>
> Standard deviations:
> [1] 83.732400 14.212402  6.489426  2.4827900
>
> Rotation:
>                 PC1         PC2         PC3         PC4
> Murder   0.04170432 -0.04482166  0.07989066 -0.99492173
> Assault  0.99522128 -0.05876003 -0.06756974  0.03893830
> UrbanPop 0.04633575  0.97685748 -0.20054629 -0.05816914
> Rape     0.07515550  0.20071807  0.97408059  0.07232502
>
>
> I want to get only:
>
>                 PC1         PC2         PC3         PC4
> Murder   0.04170432 -0.04482166  0.07989066 -0.99492173
> Assault  0.99522128 -0.05876003 -0.06756974  0.03893830
> UrbanPop 0.04633575  0.97685748 -0.20054629 -0.05816914
> Rape     0.07515550  0.20071807  0.97408059  0.07232502
>
>
> I want to be able to do this because I am actually carrying out PCA in
RExcel.
> I am able to do the PCA analysis using the "prcomp(data)" and
"GetArray"
> commands, but doing that puts all of the aforementinoed output in a single
row
> of cells instead of assigning each word and number its own individual cell.
>
> I figured this dealt more with R code than Excel, so I decided to post it
here.
>
> Can anyone help me out?  Is there a command that can carry out what
I've
> mentioned?
>
>
> Wayne
>
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