[R] group by function

[Ragia Ibrahim]

many thanks for replying,
yes I am kindly accept my pardon, I mistaken the rows from each other.... many thanks I will read them.
Ragia 

----------------------------------------
> Date: Sat, 7 Nov 2015 07:48:36 -0800
> Subject: Re: [R] group by function
> From: bgunter.4567 at gmail.com
> To: ragia11 at hotmail.com
> CC: r-help at r-project.org
>
> ??
> Row 4 has i = 2 and Measure_id =4 and therefore has value divided by
> the max of all values with that i and Measure_id, which is 1. Row 7
> has i =2 and Measure_id =2, and so is divided by the max value in all
> rows with those values of i and Measure_id, which is 2. etc. So either
> you do not understand ave() or you are incorrectly stating what you
> want.
>
> Incidentally, read ?ave, ?with and ?within. paste() is not needed and
> the call can be shortened to
>
> df <- within(df,newcol<-ave(value,i,Measure_id,FUN=function(x)x/max(x)))
>
> Finally, I suggest you learn to post in plain text (as the posting
> guide requests) to avoid possible mangling of your posts.
>
> Cheers,
> Bert
>
> Bert Gunter
>
> "Data is not information. Information is not knowledge. And knowledge
> is certainly not wisdom."
> -- Clifford Stoll
>
>
> On Sat, Nov 7, 2015 at 6:32 AM, Ragia Ibrahim <ragia11 at hotmail.com> wrote:
>> Dear group,
>> kindly, I have the following data frame
>>
>> structure(c(2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2,
>> 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1.5, 2, 1, 0, 2, 2, 1.5,
>> 0, 0, 1, 1, 2, 0, 1, 2), .Dim = c(15L, 3L), .Dimnames = list(
>> NULL, c("i", "Measure_id", "value")))
>>
>>
>>
>> it has 3 coulmns
>> I used
>> df$newcoulmn <- ave(df$value, paste( df$i, df$Measure_id), FUN= function(x) x/max(x) )
>>
>>
>> to get x /max(x) and calc probability.. but I want to do that for each source measure_id" separately that means that rows 4,7,13 ..their value should be divided by 1.5 not 2..
>>
>> rows 1,5,11 will be divided by 2 the max of their same group grouped by measure id
>> how to make such grouping
>>
>> thanks in advance
>> Ragia
>> [[alternative HTML version deleted]]
>>
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