I have an array of mode list e.g. as created from the following tapply code:

my.data <- data.frame(expand.grid(species = c(1:3), year = c(1972:2000), VA = c(1:10), SA=c(1:3)))

test <- tapply(my.data$SA, list(my.data$species,my.data$year, my.data$VA), as.character)

mode(test)
#> [1] "list"

is.array(test)
#> [1] TRUE

How do I use abind to add an additional dimension? Using abind will give me an error because of mode "list"

test2 <- abind(test, test[,,1])
#> Error in abind(test, test[, , 1]) : 
#>   can only supply one list-valued argument for ...

Thank you in advance.