data.tree: Get – R documentation

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Get

Traverse a Tree and Collect Values

Description

The Get method is one of the most important ones of the data.tree package. It lets you traverse a tree and collect values along the way. Alternatively, you can call a method or a function on each Node.

Usage

# OO-style:
#node$Get(attribute, 
#        ..., 
#        traversal = c("pre-order", "post-order", "in-order", "level", "ancestor"), 
#        pruneFun = NULL, 
#        filterFun = NULL, 
#        format = FALSE, 
#        inheritFromAncestors = FALSE)
         
# traditional:
Get(nodes, 
    attribute, 
    ..., 
    format = FALSE, 
    inheritFromAncestors = FALSE, 
    simplify = c(TRUE, FALSE, "array", "regular"))

Arguments

`nodes`	The nodes on which to perform the Get (typically obtained via `Traverse`)
`attribute`	determines what is collected. The `attribute` can be a.) the name of a field or a property/active of each `Node` in the tree, e.g. `acme$Get("p")` or `acme$Get("position")` b.) the name of a method of each `Node` in the tree, e.g. `acme$Get("levelZeroBased")`, where e.g. `acme$levelZeroBased <- function() acme$level - 1` c.) a function, whose first argument must be a `Node` e.g. `acme$Get(function(node) node$cost * node$p)`
`...`	in case the `attribute` is a function or a method, the ellipsis is passed to it as additional arguments.
`format`	if `FALSE` (the default), no formatting is being used. If `TRUE`, then the first formatter (if any) found along the ancestor path is being used for formatting (see `SetFormat`). If `format` is a function, then the collected value is passed to that function, and the result is returned.
`inheritFromAncestors`	if `TRUE`, then the path above a `Node` is searched to get the `attribute` in case it is NULL.
`simplify`	same as `sapply`, i.e. TRUE, FALSE or "array". Additionally, you can specify "regular" if each returned value is of length > 1, and equally named. See below for an example.

Value

a vector containing the atrributes collected during traversal, in traversal order. NULL is converted to NA, such that length(Node$Get) == Node$totalCount

Examples

data(acme)
acme$Get("level")
acme$Get("totalCount")
 

acme$Get(function(node) node$cost * node$p,
         filterFun = isLeaf)

#This is equivalent:
nodes <- Traverse(acme, filterFun = isLeaf)
Get(nodes, function(node) node$cost * node$p)

   
#simplify = "regular" will preserve names
acme$Get(function(x) c(position = x$position, level = x$level), simplify = "regular")

data.tree

General Purpose Hierarchical Data Structure

v1.0.0

GPL (>= 2)

Authors

Russ Hyde [ctb] (improve dependencies), Chris Hammill [ctb] (improve getting), Facundo Munoz [ctb] (improve list conversion), Markus Wamser [ctb] (fixed some typos), Pierre Formont [ctb] (additional features), Kent Russel [ctb] (documentation), Noam Ross [ctb] (fixes), Duncan Garmonsway [ctb] (fixes), Christoph Glur [aut, cre] (R interface)

Initial release

2020-07-31

Get