Help in getting info from a DataFrame

Hi

r-help-bounces at r-project.org napsal dne 02.02.2011 11:14:18:
Hi

r-help-bounces at r-project.org napsal dne 31.01.2011 15:51:16:

<snip>

Hi

thanks. I am not sure if I have understood 100% but at least I know 
now
that
there's a diference.

About this: 

lapsales
     Store      Prod qtd
 5  Aveiro Lapiseira   3
 8 Coimbra Lapiseira   1
 9 Setubal Lapiseira   1
 > lapsales[max(lapsales$qtd),"Store"]
 [1] Setubal
 Levels: Aveiro Coimbra Evora lx Setubal

 why Setubal and not Aveiro?

Can you explain me the result?
Sorry I did not look to your code and used the code I sent you as a 
solution

What do you expect max(lapsales$qtg) give you as a result?
If you changed the number qtd to 4 instead of 3 you will get
lapsales[max(lapsales$qtd),"Store"]
[1] <NA>
Levels: Aveiro Coimbra Evora lx Setubal

So R give you what you ask for. You asked for third line and you got it.

If you asked for which position is the maximum number

lapsales[which.max(lapsales$qtd),"Store"]
[1] Aveiro
Levels: Aveiro Coimbra Evora lx Setubal

You will get desired result.

Regards
Petr
Probably qtd is not what you think it is. I get

dados<- data.frame(Store = c 

("Setubal","lx","Aveiro","Coimbra","Aveiro","Evora","Aveiro","Coimbra","Setubal"),Prod=c

("BlocoDesenho","BlocoDesenho","Tinteiro","R?gua","Lapiseira","Regua","Tinteiro","Lapiseira","Lapiseira"),qtd=c
(2,1,2,1,3,1,1,1,1))
lapsales <- dados[dados$Prod=="Lapiseira",  ]
lapsales[which.max(lapsales[ , "qtd" ]), "Store"]
[1] Aveiro
Levels: Aveiro Coimbra Evora lx Setubal

and

str(lapsales)
'data.frame':   3 obs. of  3 variables:
 $ Store: Factor w/ 5 levels "Aveiro","Coimbra",..: 1 2 5
 $ Prod : Factor w/ 5 levels "BlocoDesenho",..: 2 2 2
 $ qtd  : num  3 1 1

Maybe you get something different.

Regards
Petr

thanks
AD
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Help in getting info from a DataFrame

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