CODEWITHSUNDEEP
rlistlapplysapplytapply
forecaster
forecaster

Reputation: 1159

R programming how to apply individual elements in list to a function

I have a list with multiple elements, I need to apply ets function from forecast using two elements from each list.

Below is the list dat.list each list has time series called z and a lam

## Create Dummy list
##Time series -> z, lambda - > lam
z <- ts(matrix(rnorm(30,10,10), 100, 3), start = c(1961, 1), frequency = 12)
lam <- 0.8
ap <- list(z=z,lam=lam)


z <- ts(matrix(rnorm(30,10,10), 100, 3), start = c(1971, 1), frequency = 12)
lam <- 0.5
zp <- list(z=z,lam=lam)

dat.list <- list(ap=ap,zp=zp)

Now I need take each time series z and take lam and apply it with ets function from forecast package. I used the following code.

library("forecast")
library("plyr")   
ets.f <- function(x) {
      forecast(ets(x$z, lambda = x$lam),h=12)$mean ## I need to apply lambda from list lam
    }

    ens.f <- function(x){
      mm <- llply(x,ets.f)
      tq <- matrix(unlist(mm), ncol = 12, byrow = TRUE)
      tq
    }

    fore <- llply(dat.list, ens.f)

When I run the program i get the following error "Error in x$z : $ operator is invalid for atomic vectors".

I'm not sure how to apply individual elements of a list and apply it to a function. Any help would be greatly appreciated.

Thanks so much

Also, I also tried to separate z and lam in the list and was stuck on how to apply this. I'm apoen to using the code below as well. Thanks much appreciated.

ts.l <- lapply(dat.list,'[[','z')
lam.l <- lapply(dat.list,'[[','lam')

Upvotes: 1

Views: 586

Answers (1)

akrun
akrun

Reputation: 887901

May be this helps:

lapply(dat.list, function(x) matrix(unlist(lapply(x$z,
           function(y) forecast(ets(y, lambda=x$lam), 
                        h=12)$mean)), ncol=12, byrow=TRUE))

Upvotes: 1

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