R help - Feb 2011 - Count factor if

Hi,

I have a data frame containing two columns:   

x<-as.factor(c('a','a','a','a','a','b','b','b','c','d','d','d'))
y<-c(1,3,6,8,12,3,4,7,5,6,7,10) 
X<-data.frame(x,y) 
X
   x  y
1  a  1
2  a  3
3  a  6
4  a  8
5  a 12
6  b  3
7  b  4
8  b  7
9  c  5
10 d  6
11 d  7
12 d 10

I would like to add a column that counts the number of occurences of x for
all y < focal y. So,

Xnew
   x  y  z
1  a  1  0
2  a  12  4
3  a  6  2
4  a  8  3
5  a 3  1
6  b  3  1
7  b  4  2
8  b  7  3
9  c  5  1
10 d  6  1
11 d  7  2
12 d 10  3

I guess this should be easy, but I have no clue on how to do it. Thanks very
much!
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Try this:

cbind(X, z = ave(X$y, X$x, FUN = order) - 1)


On Tue, Feb 15, 2011 at 12:33 PM, mathijsdevaan
<mathijsdevaan@gmail.com>wrote:
>
> Hi,
>
> I have a data frame containing two columns:
>
>
x<-as.factor(c('a','a','a','a','a','b','b','b','c','d','d','d'))
> y<-c(1,3,6,8,12,3,4,7,5,6,7,10)
> X<-data.frame(x,y)
> X
>   x  y
> 1  a  1
> 2  a  3
> 3  a  6
> 4  a  8
> 5  a 12
> 6  b  3
> 7  b  4
> 8  b  7
> 9  c  5
> 10 d  6
> 11 d  7
> 12 d 10
>
> I would like to add a column that counts the number of occurences of x for
> all y < focal y. So,
>
> Xnew
>   x  y  z
> 1  a  1  0
> 2  a  12  4
> 3  a  6  2
> 4  a  8  3
> 5  a 3  1
> 6  b  3  1
> 7  b  4  2
> 8  b  7  3
> 9  c  5  1
> 10 d  6  1
> 11 d  7  2
> 12 d 10  3
>
> I guess this should be easy, but I have no clue on how to do it. Thanks
> very
> much!
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Count-factor-if-tp3306856p3306856.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

	[[alternative HTML version deleted]]

>Here is a method that works despite generating a warning:
>cbind(X, z = ave(X$y, X$x, FUN = seq) - 1)
>
>David Winsemius, MD
>West Hartford, CT
I was happy a bit too early. There's still an error:

x<-as.factor(c('a','a','a','a','a','b','b','b','c','d','d','d'))
y<-c(1,3,6,8,8,3,4,7,5,6,7,10) 
X<-data.frame(x,y) 
X 
   x  y 
1  a  1 
2  a  3 
3  a  6 
4  a  8 
5  a  8 
6  b  3 
7  b  4 
8  b  7 
9  c  5 
10 d  6 
11 d  7 
12 d 10 

cbind(X, z = ave(X$y, X$x, FUN = seq) - 1)

   x  y z
1  a  1 0
2  a  3 1
3  a  6 2
4  a  8 3
5  a  8 4
6  b  3 0
7  b  4 1
8  b  7 2
9  c  5 0
10 d  6 0
11 d  7 1
12 d 10 2

Using this function provides a value of 4 in row 5, column c, while it
should be 3. Is there another way I can solve my problem? Thanks!

M
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