Re: [R] about sorting table

From: Martin Maechler <maechler_at_stat.math.ethz.ch>
Date: Thu 01 Dec 2005 - 20:05:52 EST

>>>>> "UweL" == Uwe Ligges <ligges@statistik.uni-dortmund.de> >>>>> on Thu, 01 Dec 2005 08:37:37 +0100 writes:

    UweL> herodote@oreka.com wrote:
>> hi all,
>>
>> I load a table with headers that enable me to acces it by the column names:
>>
>> tab<-read.table("blob/data.dat",h=T)
>> attach(tab)
>>
>> everythings are OK, but i try to sort this table against one of his column like this:
>>
>> tab<-tab[order(tab$IndexUI),];
>>
>> It is still ok, the table is sorted, if i type "tab" i see a sorted table.
>>
>> but, when i call the column by their names, it appears that the column isn't sorted...
>>
>> I believe that, is there a solution to attach column names another time, to reflect the effect of sorting this table?
>>
>> thks all for your answers

    UweL> see ?colnames

eehm, that won't really help here.

The problem is that Guillaume

- first attach()ed the data frame
- then changed the data frame itself,
- and then erronously assumed that the *attached* data would change.

In general, we nowadays recommend quite often against using attach() but rather use the 'data = ' argument where applicable and use with( <data frame> , <......> )
otherwise.

Martin Maechler, ETH Zurich



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