Dear R Help,

I am attempting to write a function that  takes a list of variable groups and a vector of numbers (e.g., "jtsv" would indicate one group of variables, "jtsv1", "jtsv2", etc, each of which name a variable in a data frame), and returns a list of variable group sums. For example, given list("jtsv", "ptsv") and c(1:10), where jtsv1, etc, are all numeric vectors of the same length, the function should return a list of jtsv and ptsv, where
jtsv <- jtsv1 + jtsv2 + jtsv3 + jtsv4 + jtsv5 + jtsv6 + jtsv7 + jtsv8 + jtsv9 + jtsv10
ptsv <- ptsv1 + ptsv2 + ptsv3 + ptsv4 + ptsv5 + ptsv6 + ptsv7 + ptsv8 + ptsv9 + ptsv10

So far I've used a for loop to paste together the names of the variables as character vectors, so that I can at least name the variables that I want to get, but I'm stuck on how to add together the numeric vectors that those character vectors are ultimately supposed to name. It seems like I should be able to map the primitive "+" operator onto a list or vector that contains the variable names. If that's a good way to go, what would that look like? Or if that's not a good way to go, would someone please point me in a good direction?

Sincerely,
Frank Tamborello



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