[R] data frame search

[Bart Joosen]

Thanks, couldn't find this function,

Best regards

Bart

----- Original Message ----- 
From: "Gabor Grothendieck" <ggrothendieck at gmail.com>
To: "Bart Joosen" <bartjoosen at hotmail.com>
Cc: <r-help at stat.math.ethz.ch>
Sent: Saturday, June 24, 2006 1:15 PM
Subject: Re: [R] data frame search


> Try this:
>
> which(DF1 == 4, arr.ind = TRUE)
>
>
> On 6/24/06, Bart Joosen <bartjoosen at hotmail.com> wrote:
>> Hi,
>>
>> I want to make a data frame which contains the positions of some searched 
>> values in another data frame.
>>
>> Like:
>> Dataframe 1:
>>
>> 1  2  3  4  1  2  3  4
>> 2  3  4  1  2  3  4  2
>> 4  1  2  3  2  3  4  1
>>
>> Let's say I searched on "4", then Dataframe 2 should contain:
>> x  y
>> 1  4
>> 1  8
>> 2  3
>> 2  7
>> 3  1
>> 3  7
>>
>> I have written a routine, but it seems to me that it isn't that perfect:
>> x<- 0
>>
>> y<- 0
>>
>> for (j in 1:ncol(df)) {
>>
>> for (i in 1:nrow(df)) {
>>
>> if (df[i,j] == 3) {
>>
>> x <- c(x,i)
>>
>> y <- c(y,j)
>>
>> }
>>
>> }
>>
>> }
>>
>> df2 <- data.frame(x,y)
>>
>> df2 <- df2[-1,]
>>
>> Can someone come up with an elegant/faster solution, because the ultimate 
>> goal of this routine is to analyze an jpg image.
>>
>> Kind regards
>>
>> Bart
>