Clear the list without affecting the trees in the list. Note that explcitly clearing the list is usually not necessary (e.g. when using load() )

Apply a filter on the list. Only trees for which the filter condition filter is true, remain in the list.

See also: simulate

filterRandom() selects randomly n_trees from the list and removes all other trees.

See also: filterRandomExclude

filterRandomExclude() excludes randomly n_trees trees from the list, i.e. the number of trees after execution in the list is n_trees_before - n_trees (the number of trees before the call minus the trees excluded). This is useful when you want to keep a number of trees remaining on the stand (i.e., not harvested). Note that the exclusion is relative to the current content of the list (e.g., filtered).

A typical use is to reduce the number of trees on a stand to a given number of stems (e.g., from a yield table).

See also: filterRandom

Remove the fraction of all trees [0..1] for which filter evalulates to true. Return number of removed trees. When trees are harvested, the biomass is removed from the system (compare kill/cut). When harvest() is called without parameters, then all trees that are currently in the list are removed (see also load()).

See also: simulate, kill

Kill (i.e., cut down and do not remove from the forest) the trees in the list, filtered with filter.

See also: simulate

killSaplings() provides an access to the cohorts of the sapling layer in iLand https://iland-model.org/sapling+growth+and+competition . https://iland-model.org/sapling+variables provides a list of available variables. The function removes all sapling cohorts for which expr returns true.

Note: The interface to saplings currrently much simpler compared to the interface for trees >4m.

The load() method is the main means to get all the trees of a forest stand into the list. Per default, all trees (i.e. trees>4m height) that are located on the forest stand are loaded. If filter is provided, only a subset of the trees are loaded. filter can either be a probability (between 0..1) for selecting individual trees, or an Expression using tree variables.

trees.load(0.2); // load (randomly selected) 20% of all trees
                    trees.load("rnd(0,1)<0.2)"); // the same as above, but using an Expression
                    // load a subset of trees (for which the given Expression evalulates to true):
                    trees.load("species=piab and dbh>20");

Load all trees (living trees, >4m height) of the current stand into the internal list.

The loadFromList() method is a way to copy tree list data from a different TreeList object. A typical use case is when you need to process parts of a tree lists (e.g., based on location). Per default, all trees (i.e. trees>4m height) that are located in other_listare loaded. If filter is provided, only a subset of the trees are loaded. filter can either be a probability (between 0..1) for selecting individual trees, or an Expression using tree variables. Note also, that the linked forest stand is copied as well, i.e. a later call to loadAll() would load all trees of that stand.

var my_list = new TreeList;
                    stand.trees.load('dbh > 20');
                    // loop over three species and count for each species the number of trees >20cm
                    // (note that this would have been also possible with the sum() function)
                    for (s of ['piab', 'fasy', 'lade']) {
                       const n = my_list.loadFromList(stand.trees, 'species=' + s);
                       console.log(Species '${s}' has ${n} trees >20cm.);
                    }

Calculates the mean value of a given expr that can contain any of the available tree variables. The optional filter is another expression that filters the trees that are processed. Return the mean value.

See also: sum

Return the perc th percentile (0..100) value from the list of trees. The function requires that a sort operation has been executed before this function is called. The sort() function assigns to each tree in the list a value (e.g., the dbh). The percentile function accesses those value. Without a call to sort the function returns 0 for all values. The percentile 100 returns the maximum value within the list (i.e., the value last attached to the last tree in the list).

See also:sort

Randomly shuffles the list of trees. Trees in a newly refreshed list (e.g., loadAll()) have a non-random spatial pattern. When randomness is wanted (e.g., to select randomly N trees), then randomize should be used.

Note: randomize overwrites the values of a sort call.

See also: loadAll

Check all trees of the stand and either kill or harvest those trees that are marked for that operation.

See also: simulate, harvest

sort() sorts the tree list according to the numeric value of the expression sort_expr. The sort order is ascending, i.e., after sorting the tree with the smallest value is at the beginning of the list. Descending order can be achieved by inverting the sign of the expression. A sorted list is useful for extracting percentile values or for using the incsum function of expressions [iland-model.org/Expression].

See also: percentile

spatialFilter() filters the tree that are currently in the list based on their spatial location and the content of the grid. The function checks for every tree the corresponding pixel of grid and evaluates the filter function. If the function returns true, the tree is kept (if the tree is outside of the grid the tree is removed).

Note that when not otherwise altered, the default name of a grid is simply 'x', so filtering for a certain value could be achieved by using 'x=1' as a filter.

See also: create, setOrigin

Calculates the sum of a given expr that can contain any of the available tree variables. The optional filter is another expression that filters the trees that are processed. Returns the sum of expr.

Note: counting trees that fulfill the filter expression can be expressed as: sum('1', '<filter-expr>').

See also:mean

tree(index) returns the tree with index index (index is 0-based) from the current list. The returned Javascript object is a reference to the represented tree in iLand. See Tree for more details.

See also: treeObject

treeObject(index) returns the tree with index index (index is 0-based) from the current list. A new Javascript object is created for the tree. See Tree for more details.

See also: tree