CODEWITHSUNDEEP
rlapply
Sebastian Zeki
Sebastian Zeki

Reputation: 6874

Limit recursive function based on number of recursions completed

I have a recursive function that extracts data from a database. The database is huge and the recursion takes a while and eventually ends in an Error as I have exceeded the stack. I am trying to debug the function so I would like to limit the recursion so I can look at the result before the stack error occurs.

Here is the function. How can I put a recursion limit on it? (df$relatedIdEx is just a character string from the dataframe that is used as the string to lookup a new dataframe with). If the string has already been looked up then it is skip- this is to prevent infinite loops

get_all_dfs <- function(df) {
  lapply(df$relatedIdEx, function(elem) {
    if (as.character(unlist(elem)) %in% already_lookedup) {
      print(paste("Already looked up ",elem," and skipping!"))
      return (NULL)
    } else {
      already_lookedup <<- c(already_lookedup,as.character(unlist(elem)))
    }
    next_df <- myGIConcepts(elem)

    #next_df_list<-list(next_df,my_env)
    if (nrow(next_df)>1) {
      get_all_dfs(next_df)
    } else {
      thelist<-df
    }
  })
}

Upvotes: 0

Views: 65

Answers (1)

Soren
Soren

Reputation: 2425

You can pass the counter to the function, which is a bit more clean, such as get_all_dfs <- function(df,counter). But your question implies a quick solution will do. A counter is added as follows. Note you could move it within the lapply as well, potentially, depending on where you want the counter to be or where to break.

counter <- 0
get_all_dfs <- function(df) {
  counter <<- counter+1
  if (counter > 100) return (NULL)

  lapply(df$relatedIdEx, function(elem) {
    if (as.character(unlist(elem)) %in% already_lookedup) {
      print(paste("Already looked up ",elem," and skipping!"))
      return (NULL)
    } else {
      already_lookedup <<- c(already_lookedup,as.character(unlist(elem)))
    }
    next_df <- myGIConcepts(elem)

    #next_df_list<-list(next_df,my_env)
    if (nrow(next_df)>1) {
      get_all_dfs(next_df)
    } else {
      thelist<-df
    }
  })
}

Upvotes: 1

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