Hi,
I am trying to get percentages in a more elegant way. I have a data.frame with
locations and values (counts) of species at that location. Each location is
repeated for each species i have values for and i would like to get percentages
of each species at that location. I am not sure if i am clear in my
explanations so i will paste my code below:
#####################
> x
locat val
1 a 5
2 b 5
3 b 15
4 c 5
5 c 20
6 c 5
7 c 10
8 d 5
9 d 15
10 d 10
> loc1 <- x$locat
> n <- length(loc1)
> locuniq1 <- unique(loc1)
> m <- length(locuniq1)
> counts <- seq(1:m)
>
> for (i in 1:m) {
+ count <- 0
+ for (j in 1:n) {
+ if (loc1[j]==locuniq1[i]) count <- count+1
+ counts[i] <- count
+ }
+ }
>
> percent1 <- rep(0,n)
> j <- 0
> for (i in 1:m) {
+
+ b <- x[(j+1):(j+counts[i]),]
+ total <- sum(b$val)
+ percent1[(j+1):(j+counts[i])] <- round(apply(as.matrix(b$val), 1, function(x)
{x*100/total}),2)
+ j = j+counts[i]
+ }
> x1 <- cbind(x, percent1) # this is the result i want
> x1
locat val percent1
1 a 5 100.00
2 b 5 25.00
3 b 15 75.00
4 c 5 12.50
5 c 20 50.00
6 c 5 12.50
7 c 10 25.00
8 d 5 16.67
9 d 15 50.00
10 d 10 33.33
>
################
I am wondering if there is any way to do it more efficiently, much more that
the first loop which gives how many times each location is present in the
data.frame is slow if you have a larger data.frame and not only 10 rows.
Thanks for any input and sorry if the email is on the long side,
Monica
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