[R] Find max of a row in data frame (like Excel)

[jim holtman]

Is this what you want:

> x <- read.table(textConnection("       probe_id f1 f2 f3 f4          M        A  f
+ 1 A_68_P20002076  2 58  0  0 1.51778114 6.344453 59
+ 2 A_68_P20002775 22  8 15  0 0.43419304 5.488819 59
+ 3 A_68_P20005791 43  3  0  0 0.05698666 9.830594 59
+ 4 A_68_P20005805 11 34  0  0 1.71076835 6.624038 59
+ 5 A_68_P20006729 16 44  0  0 0.85498261 6.044229 59"), header=TRUE)
> closeAllConnections()
> # 'apply' to the rows; need to convert to numeric since it is coersed to character
> x$f <- apply(x, 1, function(a) max(as.numeric(a[c('f1','f2','f3','f4')])))
> x
        probe_id f1 f2 f3 f4          M        A  f
1 A_68_P20002076  2 58  0  0 1.51778114 6.344453 58
2 A_68_P20002775 22  8 15  0 0.43419304 5.488819 22
3 A_68_P20005791 43  3  0  0 0.05698666 9.830594 43
4 A_68_P20005805 11 34  0  0 1.71076835 6.624038 34
5 A_68_P20006729 16 44  0  0 0.85498261 6.044229 44
>



On Tue, Jun 24, 2008 at 6:41 PM, Anh Tran <popophobia at gmail.com> wrote:
> Hi,
> Here's the data we have:
>
>> rs[1:5,]
>        probe_id f1 f2 f3 f4          M        A  f
> 1 A_68_P20002076  2 58  0  0 1.51778114 6.344453 59
> 2 A_68_P20002775 22  8 15  0 0.43419304 5.488819 59
> 3 A_68_P20005791 43  3  0  0 0.05698666 9.830594 59
> 4 A_68_P20005805 11 34  0  0 1.71076835 6.624038 59
> 5 A_68_P20006729 16 44  0  0 0.85498261 6.044229 59
>
> I want rs$f be the max of f1, f2, f3, f4 like a function in excel (=max(f1,
> f2, f3, f4)).
>
> How should we do it in R? I'm not familiar with programing with list. So
> please be patient
>  Thanks
> --
> Regards,
> Anh Tran
>
>        [[alternative HTML version deleted]]
>
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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?