Dowle wrote:
> From: Matthew Dowle
> Subject: Re: [R] Simple order() data frame question.
> To: r-h...@stat.math.ethz.ch
> Received: Thursday, May 12, 2011, 11:23 AM
>
> With data.table, the following is routine :
>
> DT[order(a)] # ascending
> DT[order(-a)] # desc
With data.table, the following is routine :
DT[order(a)] # ascending
DT[order(-a)] # descending, if a is numeric
DT[a>5,sum(z),by=c][order(-V1)] # sum of z group by c, just where a>5,
then show me the largest first
DT[order(-a,b)] # order by a descending then by b ascending, if a and b are
I was wondering whether it would be possible to make a method for
data.frame with sort().
I think it would be more intuitive than using the complex construction
of df[order(df$a),]
Is there any reason not to make it?
Ivan
Le 5/12/2011 15:40, Marc Schwartz a écrit :
On May 12, 2011, at 8:09 AM
On May 12, 2011, at 8:09 AM, John Kane wrote:
> Argh. I knew it was at least partly obvious. I never have been able to read
> the order() help page and understand what it is saying.
>
> THanks very much.
>
> By the way, to me it is counter-intuitive that the the command is
>
>> df1[order(df1
it to be
order( , df1[,2],decreasing=TRUE)
So clearly I don't understand what is going on but at least I a lot better off.
I may be able to get this graph to work.
--- On Thu, 5/12/11, Patrick Breheny wrote:
> From: Patrick Breheny
> Subject: Re: [R] Simple order() data
Ah, this never would have occured to me. It's rather obvious now but of
course, I'll forget it again. Note to self: Put it in the cribsheet.
Thanks very mcuy
--- On Thu, 5/12/11, Nick Sabbe wrote:
> From: Nick Sabbe
> Subject: RE: [R] Simple order() data frame question.
&
Try
(df1[order(-df1[,2]),])
Adding the minus within the [ leaves out the column (in this case column 2).
See ?"[".
HTH.
Nick Sabbe
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On 05/12/2011 08:32 AM, John Kane wrote:
Clearly, I don't understand what order() is doing and as ususl the help for
order seems to only confuse me more. For some reason I just don't follow the
examples there. I must be missing something about the data frame sort there but
what?
I originally
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