subset in dataframes

Thank you very much.

My dataframe has thousands of firms, how can I delete all of those with x<0
and keep another dataframe with firms where all x>0?

Thank you again.

Cec?lia Carmo
(Universidade de Aveiro - Portugal)

-----Mensagem original-----
De: Sarah Goslee [mailto:sarah.goslee at gmail.com]
Enviada: domingo, 2 de Outubro de 2011 13:01
Para: Cecilia Carmo
Cc: r-help at r-project.org
Assunto: Re: [R] subset in dataframes

Hi,

On Sun, Oct 2, 2011 at 7:48 AM, Cecilia Carmo <cecilia.carmo at ua.pt> wrote:

I need help in subseting a dataframe:



data1<-data.frame(year=c(2001,2002,2003,2004,2001,2002,2003,2004,

2001,2002,2003,2004,2001,2002,2003,2004),

firm=c(1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4),x=c(11,22,-32,25,-26,47,85,98,

101,14,87,56,12,43,67,54),

y=c(110,220,302,250,260,470,850,980,1010,140,870,560,120,430,670,540))

Thank you for providing a reproducible example.

data1



I want to keep the firms where all x>0 (where there are no negative values
in x)

So my output should be:

? year firm ? x ? ?y

1 ?2001 ? ?3 101 1010

2 2002 ? ?3 ?14 ?140

3 2003 ? ?3 ?87 ?870

4 2004 ? ?3 ?56 ?560

5 2001 ? ?4 ?12 ?120

6 2002 ? ?4 ?43 ?430

7 2003 ? ?4 ?67 ?670

8 2004 ? ?4 ?54 ?540



So I'm doing:

data2<-data1[data1$firm%in%subset(data1,data1$x>0),]

data2

What about finding which ones have negative values and should be deleted,

unique(data1$firm[data1$x <= 0])

[1] 1 2

And then deleting them?

data1[!(data1$firm %in% unique(data1$firm[data1$x <= 0])),]

? year firm ? x ? ?y
9 ?2001 ? ?3 101 1010
10 2002 ? ?3 ?14 ?140
11 2003 ? ?3 ?87 ?870
12 2004 ? ?3 ?56 ?560
13 2001 ? ?4 ?12 ?120
14 2002 ? ?4 ?43 ?430
15 2003 ? ?4 ?67 ?670
16 2004 ? ?4 ?54 ?540

But the result is

[1] year firm x ? ?y

<0 rows> (or 0-length row.names)

If you look at just the result of part of your code,
subset(data1,data1$x>0)
it isn't giving at all what you need for the next step: the entire
data frame for x>0.