Dear R-User,
Appreciate any helps. It looks simple, but I don't have a clue.
Given that I have a dataframe of tree population with three variables:
sp=species ,
d0=initial_size
grow=growth increment from initial size per year
How can I calculate the future growth increment of each tree for the next 3
years.
The following Rscript was written,
#----------
a0 <- data.frame(d0=seq(5,50,5) , sp=gl(2,5,10),
grow=rep(0.5,10))
a2<- list()
for( i in 1:3){
a1 <- a0$d0+a0$grow
a2[[i]] <- cbind(sp=a0$sp,d0=a1+i,yr=i)
}
as.data.frame(do.call(cbind,a2))
> as.data.frame(do.call(cbind,a2))
sp d0 yr sp d0 yr sp d0 yr
1 1 6.5 1 1 7.5 2 1 8.5 3
2 1 11.5 1 1 12.5 2 1 13.5 3
3 1 16.5 1 1 17.5 2 1 18.5 3
4 1 21.5 1 1 22.5 2 1 23.5 3
5 1 26.5 1 1 27.5 2 1 28.5 3
6 2 31.5 1 2 32.5 2 2 33.5 3
7 2 36.5 1 2 37.5 2 2 38.5 3
8 2 41.5 1 2 42.5 2 2 43.5 3
9 2 46.5 1 2 47.5 2 2 48.5 3
10 2 51.5 1 2 52.5 2 2 53.5 3
#-----
but the results did not produce the expected future d0. I think its my R script
"d0=a1+i" in the " a2[[i]] <- cbind(sp=a0$sp,d0=a1+i,yr=i)". Interested to
know the correct way of writing the repeated loops in R.
The expected results is:
sp d0 yr sp d0 yr sp d0 yr
1 1 6.5 1 1 7.0 2 1 7.5 3
2 1 11.5 1 1 12.0 2 1 12.5 3
3 1 16.5 1 1 17.0 2 1 17.5 3
4 1 21.5 1 1 22.0 2 1 22.5 3
5 1 26.5 1 1 27.0 2 1 27.5 3
6 2 31.5 1 2 32.0 2 2 32.5 3
7 2 36.5 1 2 37.0 2 2 37.5 3
8 2 41.5 1 2 42.0 2 2 42.5 3
9 2 46.5 1 2 47.0 2 2 47.5 3
10 2 51.5 1 2 52.0 2 2 52.5 3
Thanking you in advance for any helps.
Abd Rahman
Note: the fixed grow value of 0.5 is only an example. The real data may use
growth equation to calculate the increment in a single year.
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