[R] order intervals in a data.frame

[Peter Dalgaard]

Paul Smith wrote:
> On 9/6/07, João Fadista <Joao.Fadista at agrsci.dk> wrote:
>   
>> I would like to know how can I order a data.frame with increasing the dat$Interval (dat$Interval is a factor). There is an example below.
>>
>> Original data.frame:
>>
>>     
>>> dat
>>>       
>>                  Interval               Number_reads
>>                   0-100                         685
>>                200-300                         744
>>                100-200                        1082
>>                300-400                        4213
>>
>>
>>     
>>> Desired_dat:
>>>       
>>                  Interval               Number_reads
>>                   0-100                          685
>>                 100-200                       1082
>>                 200-300                         744
>>                 300-400                       4213
>>     
>
> What about
>
> Desired_dat <- dat[match(dat$Interval,sort(dat$Interval)),]
>   
dat[order(dat$Interval),]

would be more to the point, but it is a bit fortuitous that it works at
all (split the first group at 50 and you'll see).

This (or at least something like it) should sort according to left
endpoints:

o <- order(as.numeric(sub("-.*", "", dat$Interval)))
dat[o,]

> ?
>
> Paul
>
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>   


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