R help - May 2011 - Zero counts in an aggregate function

Dear R-users,
 
I've searched for an answer to my question, but so far haven't been able
to
find a solution. Its likely a simple issue, but have no idea how to do this.

A simplified version my (very large) data set looks like
this:
>
> bugs
   FRUIT SEED_ID SURVIVE
1      1       A       1
2      1       B       1
3      1       C       1
4      1       D       0
5      1       E       1
6      1       F       0
7      2       A       1
8      2       B       1
9      2       C       1
10     2       D       1
11     2       E       1
12     2       F       1
13     3       A       0
14     3       B       0
15     3       C       0
16     3       D       0
17     3       E       0
18     3       F       0

What I would like to do is aggregate seeds per fruit and reorganize the
SURVIVE data into counts.
I would like to add columns with counts of the number of 1s (alive) and 0s
(dead) in each so that my data looks like this:


   FRUIT  ALIVE  DEAD
1     1        4         2
2     2        6         0
3     3        0         6

I have managed do do this using "aggregate" with FUN=sum for the 1
values...

bugsALIVE<-aggregate(bugs$SURVIVE,by=list(bugs$FRUIT),FUN=sum,na.rm=TRUE)

 ...but am having trouble figuring out how to get counts of the 0 values
since there is no built-in "count" function.
I have tried to write my own function but I am fairly new to R and writing
functions and have not figured out how to only count 0s within each value of
"FRUIT"
Something like...

count<-function(x){length(x==0)}

However, when I try this it still counts all 6 seeds per fruit. How can I
write a function to only count zero values for each value of "FRUIT"?
Or is
there a better/simpler way than using the aggregate function?

Any help is appreciated!
Thanks,
Noelle


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On Mon, May 16, 2011 at 11:56 PM, Jorge Ivan Velez  wrote:

    Hi Noelle,

    Try using 

    count2 <- function(x)  sum(x == 0)

    or, for all at once (untested),

    foo <- function(x) c( alive = sum(x == 1), dead = sum(x == 0))
    with(bugs, tapply(SURVIVE, FRUIT, foo))

    HTH,
    Jorge

Hi Jorge,

The first bit of code didn't seem to work, but the second one did!

tapply worked but I also inserted "foo" into the aggregate code and
was also
able to add the "alive" and "dead" columns to my data.

Thanks very much for your help!

Noelle
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