Dear R users,
I have run into a problem using if...else and I hope you can shed some light on
it. I am using R version 2.2.0.1.
I have the following data frame:
> head(dat2f)
year tot_km3y
[1,] 1964 0.1876854
[2,] 1965 0.1835116
[3,] 1966 0.1915012
[4,] 1967 0.1869758
[5,] 1968 0.2249865
[6,] 1969 0.1916011
I need to pick out the median year, and since there are an even number of data,
I cannot use 'median' directly since it gives me a non-existent year/discharge.
I found a way to get around that with the following:
md <- dat2f[, list(med_year = max(year[which(abs(tot_km3y - median(tot_km3y))
== min(abs(tot_km3y - median(tot_km3y)))) ]), med_TotQ = median(tot_km3y))]
(I really only need the year, not the actual discharge with that year, which is
why I left med_TotQ as the true median)
However, I have some data sets that have an odd number of data for which the
following works perfectly:
md <-dat2f[, list(med_year = year[which(tot_km3y == median(tot_km3y))],
med_TotQ = median(tot_km3y))]
Thus, I would like to apply the above calculations depended on the condition of:
length(dat2f$year)%%2==0
I put it all together as below:
if (length(dat2f$year)%%2==0) {
md <-dat2f[, list(med_year = max(year[which(abs(tot_km3y - median(tot_km3y))
== min(abs(tot_km3y - median(tot_km3y)))) ]), med_TotQ = median(tot_km3y))] }
else {
md <-dat2f[, list(med_year = year[which(tot_km3y == median(tot_km3y))],
med_TotQ = median(tot_km3y))]
}
Each individual piece works perfectly on its own, but together I get the
following error:
> if (length(dat2f$year)%%2==0) {
+ md <-dat2f[, list(med_year = max(year[which(abs(tot_km3y -
median(tot_km3y)) == min(abs(tot_km3y - median(tot_km3y)))) ]), med_TotQ =
median(tot_km3y))] }
> else {
Error: unexpected 'else' in "else"
> md <-dat2f[, list(med_year = year[which(tot_km3y == median(tot_km3y))],
> med_TotQ = median(tot_km3y))]
> }
Error: unexpected '}' in " }"
>
When I tried to look up "else" I got this error:
> ?else
Error: unexpected 'else' in "?else"
I have used exactly the same set up with if...else in other code and it worked
fine then. I tried to run it again, and I got the same error as above. What is
the problem? I hope it isn't something simple and silly!
I realize that I can use the first line:
md <- dat2f[, list(med_year = max(year[which(abs(tot_km3y - median(tot_km3y))
== min(abs(tot_km3y - median(tot_km3y)))) ]), med_TotQ = median(tot_km3y))]
for all data sets and it will give me the median for both odd and even-length
data sets, but it is now about the principle; why won't the if...else work?
Thank you very much for your time!
Kara
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