The nl class (nested logit) is derived from the mnl class, and retains all that class' methods, in addition to the ones listed here.

The nnnl class (non-normalized nested logit) is derived from the nl class, but adds no new methods, and can be operated in the same way as the nl class. However, the non-normalized nested logit is not consistent with utility maximization theory, and ELMWorks does not recommend that you use this model unless you fully understand what you are doing and have a good reason to want this particular model structure.

Constructor

nl(ec as core, model_name as string)

nnnl(ec as core, model_name as string)

ec

The core object from which to derive this model.

model_name

The name of the model. Using an existing name will automatically load the existing model.

Methods

node (logsum_name as string, logsum_code as string, nest_members as list of strings, optional parameter_value as float, optional constraint as int, optional std_err as float, optional bind_variable_name as string, optional bind_ratio as float) → status as string

node (logsum_name as string, logsum_code as int, nest_members as list of ints, optional parameter_value as float, optional constraint as int, optional std_err as float, optional bind_variable_name as string, optional bind_ratio as float) → status as string

item_name

this is a string describing the variable, in the format of [table_name.]variable_name[@alternative_name]

logsum_name

the name of the nest

logsum_code

The code number of the nest, which is added to the set of alternative codes. You may alternatively use strings as node codes, but it is best not to mix-and-match in one model.

nest_members

the code numbers of nest members, which can be an elemental alternative or another nest

parameter_value

an initial value for the logsum parameter (default=1)

constraint

a 1 to indicate the parameter is constrained to the initial value, 0 otherwise (default=0)

std_err

the standard error of the initial parameter (assumes that parameter was estimated already)

bind_variable_name

where a parameter is constrained equal to another in the same model uses table_name.variable_name[@alternative_name] format of the other parameter if the other parameter is another logsum parameter, use just the logsum_name of that parameter

bind_ratio

the multiplier on the free-floating parameter's value used to create this parameter (default=1)

status

returns OK on success, OOPS on error.

connect_nodes (upper_node_code as string, lower_node_code as string) → status as string

connect_nodes (upper_node_code as int, lower_node_code as int) → status as string

upper_node_code

The code of the upper (closer to root, farther from elemental alternatives) node.

lower_node_code

The code of the lower (closer to elemental alternatives, farther from root) node.

disconnect_nodes (upper_node_code as string, lower_node_code as string) → status as string

disconnect_nodes (upper_node_code as int, lower_node_code as int) → status as string

upper_node_code

The code of the upper (closer to root, farther from elemental alternatives) node.

lower_node_code

The code of the lower (closer to elemental alternatives, farther from root) node.

print_node (node_code as string) → node_description as string

print_node (node_code as int) → node_description as string

print_node () → node_description as string

node_code

The code of the relevant node. If omitted, will return a decription of all nodes in the model.