Re: [R] apply with a division

From: Abhijit Dasgupta <adasgupt_at_mail.jci.tju.edu>
Date: Thu, 03 Jul 2008 22:34:20 -0400

Won't scale(x,center=F, scale=x[1,]) do the trick?

--

  Abhijit

Quoting Gabor Grothendieck <ggrothendieck_at_gmail.com>:


> This should work whether your data, x, is a data frame or a matrix:
>
> x / x[rep(1, nrow(x)),]
>
>
> On Thu, Jul 3, 2008 at 6:04 PM, Greg Kettler <gkettler_at_gmail.com>
wrote:
>> Hi,
>> I'd like to normalize a dataset by dividing each row by the first
row.
>> Very simple, right?
>> I tried this:
>>
>>> expt.fluor
>>   X1  X2  X3
>> 1 124 120 134
>> 2 165 163 174
>> 3  52  51  43
>> 4 179 171 166
>> 5 239 238 235
>>
>>> first.row <- expt.fluor[1,]
>>> normed <- apply(expt.fluor, 1, function(r) {r / first.row})
>>> normed
>> [[1]]
>>   X1 X2 X3
>> 1  1  1  1
>>
>> [[2]]
>>         X1       X2       X3
>> 1 1.330645 1.358333 1.298507
>>
>> [[3]]
>>          X1    X2        X3
>> 1 0.4193548 0.425 0.3208955
>>
>> [[4]]
>>         X1    X2       X3
>> 1 1.443548 1.425 1.238806
>>
>> [[5]]
>>         X1       X2       X3
>> 1 1.927419 1.983333 1.753731
>>
>> Ugly! The values are right, but why didn't I get another 2D array
>> back? Shouldn't the division in my inline function return a
vector?
>>
>> Thanks,
>> Greg
>>
>> ______________________________________________
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http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help_at_r-project.org mailing list
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> and provide commented, minimal, self-contained, reproducible code.
>
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Received on Fri 04 Jul 2008 - 02:54:10 GMT

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