[R] Accessing the elements of summary(prcomp(USArrests))

[Prof Brian Ripley]

Hints:

(i) List the function by stats:::summary.prcomp . You will see that 
the table is component 'importance' of the list result. So take a look 
at summary(prcomp(USArrests))$importance[2, ]

(ii) This looks a lot like screeplot().

(iii) prcomp(USArrests) is inappropriate, as the help file for 
prcomp stresses.

On Wed, 16 Jun 2010, Josh B wrote:

> Hello again,
>
> I was hoping one of you could help me with this problem. Consider the sample data from R:
>
>> summary(prcomp(USArrests))
> Importance of components:
>                          PC1     PC2    PC3     PC4
> Standard deviation     83.732 14.2124 6.4894 2.48279
> Proportion of Variance  0.966  0.0278 0.0058 0.00085
> Cumulative Proportion   0.966  0.9933 0.9991 1.00000
>
> How do I access the information contained within this summary? For instance, let's say I wanted to make a graph based on the second row ("Proportion of Variance").
>
> Please rest assured this is not a homework assignment. I'm just a relatively novice R user trying to do stuff that's often over my head.
>
> Thanks in advance,
> -----------------------------------
> Josh Banta, Ph.D
> Center for Genomics and Systems Biology
> New York University
> 100 Washington Square East
> New York, NY 10003
> Tel: (212) 998-8465
> http://plantevolutionaryecology.org
>
>
>
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>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595