Helper functions :

- get a raw object from its fullname
- get the printing name of an object
- get the fullname of an object from its base name and parent
- get the size of an object by its fullname
- get the type of an object by its fullname

functions.Rmd

@@ -4,6 +4,118 @@ title: R object browser functions
 
 # Description
 
+## Get object
+
+Get an object from its full qualifying name (*fullname*).
+
+```{r get object}
+##' Get an object
+##'
+##' Get an object from its fullname
+##' @title Get an object
+##' @param fullname A string with the fullname of an object
+##' @return The object
+get_object <- function(fullname)
+{
+  eval(parse(text = fullname))
+}
+```
+
+## Get name
+
+Get the printing name of an object given its identifier.
+Names come in quoted if the object is named, or as an index number.
+The return name is unquoted or surrounded with double brackets
+
+```{r get name}
+##' Get an object name
+##'
+##' Return the printing name of an object as given to print_object
+##' @title
+##' @param object A string with the name of an object within its parent
+##' @return The name of the object or its index in brackets
+get_name <- function(object)
+{
+  if (substr(object, 1, 1) == "\"")
+    substr(object, 2, nchar(object) - 1)
+  else
+    paste0("[[", object, "]]")
+}
+```
+## Get fullname
+
+Get the fullname of an object given its identifier and fullname of the parent
+
+```{r get fullname}
+##' Get an object fullname
+##'
+##' Get the fullname of an object
+##' by prepending its parent and indexing by name/position
+##' @title Get fullname
+##' @param object A string with the name of an object
+##' @param parent A string with the name of the parent
+##' @return The full object name
+get_fullname <- function(object, parent)
+{
+  if (parent == "")
+    fullname <- gsub("\"", "`", object)
+  else if (substr(parent, nchar(parent) - 1, nchar(parent)) == "::")
+    fullname <- paste0(parent, gsub("\"", "`", object))
+  else
+    fullname <- paste0(parent, "[[", object, "]]")
+
+  tryCatch(get_object(fullname),
+           error = function(e) fullname <<- gsub("::", ":::", fullname))
+
+  fullname
+}
+```
+
+## Get type
+
+Get the type / class / mode of an object from its fullname.
+
+```{r get type}
+##' Get type of an object
+##'
+##' Get the type of an object
+##' @title Get object type
+##' @param fullname A string with the fullname of an object
+##' @return The type of the object
+get_type <- function(fullname)
+{
+  class(get_object(fullname))[[1]]
+}
+```
+
+## Get size
+
+Get the size of an object given its fullname.
+
+```{r get size}
+##' Get an object size
+##'
+##' Get the size of an object:
+##' - list : length
+##' - dataframe : nrow × length
+##' -
+##' @title
+##' @param fullname A string with the fullname of an object
+##' @param type The type of the object
+##' @return The size of the object
+get_size <- function(fullname, type)
+{
+  object <- get_object(fullname)
+
+  switch(type,
+         "environment" = length(objects(object)),
+         "pkg" = length(objects(object)),
+         "data.frame" = paste0(ncol(object), " × ", nrow(object)),
+         "matrix" = paste0(ncol(object), " × ", nrow(object)),
+         "function" = length(formals(object)),
+         length(object))
+}
+```
 ## Print
 
 ### Package