Question

I am trying to write a loop that will summarize my set of matrices that all start with the same name plus a number (e.g. “day11”). However, in each run of the loop the number of matrices varies.

Without the loop it can be done once like this:

combmat<-(day1+day3+day4+day5+day6+day8+day9+day10+day11+day12+day13+day14+day15+day16+day17+day18+day19+day20+day22+day23+day24+day25+day26+day27+day28+day29)

I have tried

sum(list=ls(pattern="^day"))

without any luck …

Thank you!

Answer 1

Maybe something like

day1<-matrix(c(1:4),2,2)
day2<-matrix(c(1:4),2,2)
day3<-matrix(c(1:4),2,2)
day4<-matrix(c(1:4),2,2)

list=ls(pattern="^day")

res<-lapply(list,"get")

do.call("sum",res)

> do.call("sum",res)
[1] 40

will work for you

get returns the value of a named object. So get("x") would return the variable x