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
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