[R] Question about rank() function

[Moshe Olshansky]

Hi,

I believe that the reason is that even though the first 4 elements of your fmodel look equal (when rounded to 4 decimal places) they are actually not.
To check this try
fmodel[1:4]-fmodel[1]

--- On Thu, 11/2/10, Something Something <mailinglists19 at gmail.com> wrote:

> From: Something Something <mailinglists19 at gmail.com>
> Subject: [R] Question about rank() function
> To: r-help at r-project.org
> Received: Thursday, 11 February, 2010, 6:23 PM
> Hello,
> 
> I am trying to get the 'rank' function to work for me, but
> not sure what I
> am doing wrong.  Please help.
> 
> I ran the following commands:
> 
> data = read.table("test1.csv", head=T, as.is=T,
> na.string=".", row.nam=NULL)
> X1 = as.factor(data[[3]])
> X2 = as.factor(data[[4]])
> X3 = as.factor(data[[5]])
> Y = data[[2]]
> model = lm(Y ~ X1*X2*X3, na.action = na.exclude)
> fmodel = fitted(model)
> fmodel
> (First line is shown below.....)
> 
> 
>        1     
>   2        3     
>   4        5     
>   6        7     
>   8
>    9       10 
>      11   
>    12       13 
>      14   
>    15       16
> 17
> 180.3763 180.3763 180.3763 180.3763 180.4546 180.3763
> 177.9245 177.9245
> 181.3859 180.3763       NA
> 180.4546 180.3763 180.4546 180.3763 180.3763
> 180.4546
> 
> Then I run:
> fmodel.rank = rank(fmodel)
> fmodel.rank
> (First line is shown below....)
> 
>     1     2 
>    3     4 
>    5     6 
>    7     8 
>    9    10    11 
>   12
>  13    14    15    16 
>   17    18    19   
> 20    21    22    23 
>   24    25
>    26
> 375.0 222.0  68.5  68.5 402.5 222.0 
> 33.5  33.5 465.5 222.0 500.0 402.5
> 222.0 402.5 222.0 222.0 378.5 222.0 222.0 222.0 222.0 222.0
> 402.5 222.0
>  33.5 222.0
> 
> 
> As you can see, first 4 values of 'fmodel' are 180.3763, so
> after running
> rank(fmodel) I expected the ranks of first 4 to be the
> same, but they are
> not.  What am I doing wrong?  Please let me
> know.  Thanks.
> 
>     [[alternative HTML version deleted]]
> 
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