tree_sample: The function 'tree_sample' creates tree sample objects. Such...

In AWF-GAUG/fisim: Forest Inventory Simulator (fisim) is a package for simulating response and samplign designs common in forest inventories.

Description

The function tree_sample creates tree sample objects. Such objects assign individual tree information from the population to the sample locations following a particular response design. The function is only used internally by extract_data.

Usage

tree_sample(data, r_design, r_design_parm)

Arguments

data	A data.table object holding individual tree data together with identifiers that indicate the sample and the point location at which trees were selected.
r_design	A character string indicating the type of the response design. One of the following: "fixed_area", "k_tree", "angle_count".
r_design_parm	A response design specific parameter of type numeric. For "fixed_area" the plot radius in meter; for "k_tree" the number of trees closest to the sample location; for "angle_count" the basal area factor.

Details

The data.table object (data) should have the following columns:

• id_sample

• id_point

• id_tree

• id_stem

• x_tree

• y_tree

• is_dead

• dbh

• ba

• n

• f_edge

• ef

Some response designs (currently only k_tree), may have additional alternative expansion factors as optional approximations, where unbiased estimators are missing or difficult to derive. As the column names for these alternatives ef_alt1 and ef_alt2 are used.

Value

1. $data A data.table object as described above.

2. $r_design

3. $r_design_parm

AWF-GAUG/fisim documentation built on May 28, 2019, 11:02 a.m.