Get children values — children • XploRer

Get attribute values from the children of a node.

children(
  attribute,
  node = NULL,
  scale = NULL,
  symbol = NULL,
  link = NULL,
  filter_fun = NULL,
  continue = TRUE
)

Arguments

attribute	Any node attribute (as a character)
node	The MTG node
scale	An integer vector for filtering the `.scale` of the children (i.e. the SCALE column from the MTG classes).
symbol	A character vector for filtering the children by the name of their `.symbol` (i.e. the SYMBOL column from the MTG classes).
link	A character vector for filtering the `.link` with the children
filter_fun	Any filtering function taking a node as input, e.g. `data.tree::isLeaf()`
continue	If a child is not of the right `scale`, continue until the `scale` required is met if `TRUE`, or returns `NA` if `FALSE`.

Value

The attribute values from the children of the node

Details

This function is mainly intended to be used with mutate_mtg(). In this case, the node argument can be left empty (or you can put node = node equivalently).

Examples

filepath= system.file("extdata", "simple_plant.mtg", package = "XploRer")
MTG = read_mtg(filepath)
#> Warning: the condition has length > 1 and only the first element will be used
#> Warning: the condition has length > 1 and only the first element will be used
#> Warning: the condition has length > 1 and only the first element will be used
#> Warning: the condition has length > 1 and only the first element will be used

# node_6 has one child:
children("Length", node = extract_node(MTG, "node_6"))
#> node_7 
#>     12 

# Using node 4 as reference now:
node_4 = extract_node(MTG, "node_4")
# node_4 has two children, returns two values:
children("Length", node = node_4)
#> node_5 node_6 
#>     10      6 
# To get the names of those children:
children("name", node = node_4)
#>   node_5   node_6 
#> "node_5" "node_6" 

# The width is not available for one child ("node_6"):
children("Width", node = node_4)
#> node_5 node_6 
#>      6     NA 

# We can filter by scale if we need to return the values for some scales only:
children("Width", node = node_4, symbol = "Leaf")
#> node_5 node_7 
#>      6      7 
# Here we get the value of node_7 also, because its parent "node_6" is not of scale
# "Leaf", so it was filtered out. It you need the values for one scale, but not
# making a recursive search from one scale to another until finding the required scale,
# you can put the `continue` argument to `FALSE`:

children("Width", node = node_4, symbol = "Leaf", continue = FALSE)
#> node_5 
#>      6 

# To get the values of the children of each node:
mutate_mtg(MTG, children_width = children("Width"))
print(MTG, "Width", "children_width")
#>                    levelName Width children_width
#> 1 node_1                        NA               
#> 2  °--node_2                    NA               
#> 3      °--node_3                NA              1
#> 4          °--node_4             1          6, NA
#> 5              ¦--node_5         6               
#> 6              °--node_6        NA              7
#> 7                  °--node_7     7               

# And using only the bodes with symbol "Leaf":
mutate_mtg(MTG, children_width2 = children("Width", symbol = "Leaf", continue = FALSE))
print(MTG, "Width", "children_width2")
#>                    levelName Width children_width2
#> 1 node_1                        NA              NA
#> 2  °--node_2                    NA              NA
#> 3      °--node_3                NA              NA
#> 4          °--node_4             1               6
#> 5              ¦--node_5         6              NA
#> 6              °--node_6        NA               7
#> 7                  °--node_7     7              NA