I see many people running into a similar issue with great answers but I believe this is an unanswered variation to this question!

I have a graph

g <- reactive(graph_from_dataframe(df))

Now I want to assign a degree property to this.

V(g())$degree <- degree(g())

This howevers throws the null assignment error but I don't know how to assign it without calling g. I avoided this by assigning the degree property inside an output$... however this heavily violates DRY and leads to double degree calculation.

CodePudding user response：

I guess the following syntax should work

V(g)$degree <- degree(g)

CodePudding user response：

I do not think that reactive(.) objects take assignments.

Two thoughts:

1. Use reactiveVal:

   g <- reactiveVal()
   observeEvent(df, {
     newg <- graph_from_dataframe(df)
     V(newg)$degree <- degree(new)
     g(newg)
   })
   

2. Handle the $degree assignment in the original reactive:

   g <- reactive({
     newg <- graph_from_dataframe(df)
     V(newg)$degree <- degree(newg)
     newg
   })