[R] What an element in loading is missing? (princomp)

Kingsford Jones kingsfordjones at gmail.com
Mon Oct 19 21:35:18 CEST 2009


Peng,

It's generally useful to know the class of the object you are working
with, and the methods available for that class.  This would have led
you to the 'loadings' help page.

> class(pca_result$loadings)
[1] "loadings"
> methods(class='loadings')
[1] print.loadings*

   Non-visible functions are asterisked
> ?print.loadings

and notice the cutoff argument...

hth,

Kingsford


On Mon, Oct 19, 2009 at 12:25 PM, Peter Ehlers <ehlers at ucalgary.ca> wrote:
> You misunderstood my comment; perhaps I was too cryptic.
> I intended you to look up help(loadings) where the
> argument "cutoff" is pretty clearly indicated to default
> to 0.1.
>
>  -Peter Ehlers
>
> Peng Yu wrote:
>>
>> On Mon, Oct 19, 2009 at 1:58 AM, Peter Ehlers <ehlers at ucalgary.ca> wrote:
>>>
>>> Peng Yu wrote:
>>>>
>>>> Please see below that [3,1] of loadings is not printed. I am wondering
>>>> what the problem is?
>>>
>>> Not trying ?loadings, perhaps??
>>
>> 'loadings' gives me the same thing.
>>
>>> pca_result$loadings
>>
>> Loadings:
>>     Comp.1 Comp.2 Comp.3 Comp.4
>> [1,]  0.556  0.378 -0.467 -0.574
>> [2,] -0.511  0.266 -0.761  0.299
>> [3,]        -0.887 -0.425 -0.169
>> [4,] -0.651         0.152 -0.744
>>
>>               Comp.1 Comp.2 Comp.3 Comp.4
>> SS loadings      1.00   1.00   1.00   1.00
>> Proportion Var   0.25   0.25   0.25   0.25
>> Cumulative Var   0.25   0.50   0.75   1.00
>>>
>>> loadings(pca_result)
>>
>> Loadings:
>>     Comp.1 Comp.2 Comp.3 Comp.4
>> [1,]  0.556  0.378 -0.467 -0.574
>> [2,] -0.511  0.266 -0.761  0.299
>> [3,]        -0.887 -0.425 -0.169
>> [4,] -0.651         0.152 -0.744
>>
>>
>>
>>
>>
>>>>> set.seed(0)
>>>>> m=10
>>>>> n=4
>>>>> X=replicate(n,rnorm(m))
>>>>> pca_result=princomp(X)
>>>>> svd_result=svd(apply(X,2,function(x){x-mean(x)}))
>>>>> pca_result$loadings
>>>>
>>>> Loadings:
>>>>    Comp.1 Comp.2 Comp.3 Comp.4
>>>> [1,]  0.867  0.306 -0.281 -0.275
>>>> [2,] -0.215  0.532 -0.614  0.541
>>>> [3,]        -0.682 -0.713 -0.155
>>>> [4,] -0.448  0.397 -0.186 -0.780
>>>>
>>>>              Comp.1 Comp.2 Comp.3 Comp.4
>>>> SS loadings      1.00   1.00   1.00   1.00
>>>> Proportion Var   0.25   0.25   0.25   0.25
>>>> Cumulative Var   0.25   0.50   0.75   1.00
>>>>>
>>>>> svd_result$v
>>>>
>>>>           [,1]       [,2]      [,3]       [,4]
>>>> [1,] -0.86704537 -0.3060826 0.2810007 -0.2749261
>>>> [2,]  0.21540928 -0.5321956 0.6144209  0.5411595
>>>> [3,]  0.03936291  0.6823365 0.7134127 -0.1546279
>>>> [4,]  0.44752846 -0.3968605 0.1859243 -0.7795205
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>>
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>




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