Reordering Symbols

In order to write the contents of the Container, it is required that the symbols are sorted such that, for example, a Set used as a domain of another symbol appears before that symbol. The Container will try to establish a valid ordering when writing the data. This type of situation could be encountered if the user is adding and removing many symbols (and perhaps rewriting symbols with the same name). Users should attempt to only add symbols to a Container once, and care must be taken when naming. The method reorderSymbols attempts to fix symbol ordering problems. The following example shows how this can occur:

Example Symbol reordering

library(gamstransfer)
m <- Container$new()
i <- Set$new(m, "i", records = paste0("i", 1:5))
j <- Set$new(m, "j", i, records = paste0("i", 1:3))

> m$listSymbols()
[1] "i" "j"

# now we remove the set i and recreate the data
m$removeSymbols("i")
i = Set$new(m, "i", records = paste0("i", 1:5))

> m$isValid()
[1] TRUE

Since the link to i is broken, Set j is now invalid. The user has to manually set the domain again.

# fix the domain reference in the set j
j$domain <= i

> m$listSymbols()
[1] "j" "i"

Now even though j is valid, the symbols are out of order. The order can be fixed as follows.

# calling reorderSymbols() will order the list properly,
# but the domain reference in j is now broken

m$reorderSymbols()

> m$listSymbols()
[1] "i" "j"

> m$isValid()
[1] TRUE