# Functions to Access and Edit the Main netsim_dat Object in Network Models These `get_`, `set_`, `append_`, and `add_` functions allow a safe and efficient way to retrieve and mutate the main `netsim_dat` class object of network models (typical variable name `dat`). ```r get_attr_list(dat, item = NULL) get_attr(dat, item, posit_ids = NULL, override.null.error = FALSE) add_attr(dat, item) set_attr(dat, item, value, posit_ids = NULL, override.length.check = FALSE) append_attr(dat, item, value, n.new) remove_node_attr(dat, posit_ids) get_epi_list(dat, item = NULL) get_epi(dat, item, at = NULL, override.null.error = FALSE) add_epi(dat, item) set_epi(dat, item, at, value) get_param_list(dat, item = NULL) get_param(dat, item, override.null.error = FALSE) add_param(dat, item) set_param(dat, item, value) get_control_list(dat, item = NULL) get_control(dat, item, override.null.error = FALSE) get_network_control(dat, network, item, override.null.error = FALSE) add_control(dat, item) set_control(dat, item, value) get_init_list(dat, item = NULL) get_init(dat, item, override.null.error = FALSE) add_init(dat, item) set_init(dat, item, value) append_core_attr(dat, at, n.new) ``` ## Arguments - `dat`: Main `netsim_dat` object containing a `networkDynamic` object and other initialization information passed from `netsim`. - `item`: A character vector containing the name of the element to access (for `get_` functions), create (for `add_` functions), or edit (for `set_` and `append_` functions). Can be of length > 1 for `get_*_list` functions. - `posit_ids`: For `set_attr` and `get_attr`, a numeric vector of posit_ids to subset the desired `item`. - `override.null.error`: If TRUE, `get_` will return NULL if the `item` does not exist instead of throwing an error. (default = FALSE). - `value`: New value to be attributed in the `set_` and `append_` functions. - `override.length.check`: If TRUE, `set_attr` allows the modification of the `item` size. (default = FALSE). - `n.new`: For `append_core_attr`, the number of new nodes to initiate with core attributes; for `append_attr`, the number of new elements to append at the end of `item`. - `at`: For `get_epi`, the timestep at which to access the specified `item`; for `set_epi`, the timestep at which to add the new value for the epi output `item`; for `append_core_attr`, the current time step. - `network`: index of network for which to get control ## Returns A vector or a list of vectors for `get_` functions; the main list object for `set_`, `append_`, and `add_` functions. ## Core Attribute The `append_core_attr` function initializes the attributes necessary for EpiModel to work (the four core attributes are: "active", "unique_id", "entrTime", and "exitTime"). These attributes are used in the initialization phase of the simulation, to create the nodes (see `initialize.net`); and also used when adding nodes during the simulation (see `arrivals.net`). ## Mutability The `set_`, `append_`, and `add_` functions DO NOT modify the `netsim_dat` object in place. The result must be assigned back to `dat` in order to be registered: `dat <- set_*(dat, item, value)`. ## `set_` and `append_` vs `add_` The `set_` and `append_` functions edit a pre-existing element or create a new one if it does not exist already by calling the `add_` functions internally. ## Examples ```r dat <- create_dat_object(control = list(nsteps = 150)) dat <- append_core_attr(dat, 1, 100) dat <- add_attr(dat, "age") dat <- set_attr(dat, "age", runif(100)) dat <- set_attr(dat, "status", rbinom(100, 1, 0.9)) dat <- append_attr(dat, "status", 1, 10) dat <- append_attr(dat, "age", NA, 10) get_attr_list(dat) get_attr_list(dat, c("age", "active")) get_attr(dat, "status") get_attr(dat, "status", c(1, 4)) dat <- add_epi(dat, "i.num") dat <- set_epi(dat, "i.num", 150, 10) dat <- set_epi(dat, "s.num", 150, 90) get_epi_list(dat) get_epi_list(dat, c("i.num", "s.num")) get_epi(dat, "i.num") get_epi(dat, "i.num", c(1, 4)) dat <- add_param(dat, "x") dat <- set_param(dat, "x", 0.4) dat <- set_param(dat, "y", 0.8) get_param_list(dat) get_param_list(dat, c("x", "y")) get_param(dat, "x") dat <- add_init(dat, "x") dat <- set_init(dat, "x", 0.4) dat <- set_init(dat, "y", 0.8) get_init_list(dat) get_init_list(dat, c("x", "y")) get_init(dat, "x") dat <- add_control(dat, "x") dat <- set_control(dat, "x", 0.4) dat <- set_control(dat, "y", 0.8) get_control_list(dat) get_control_list(dat, c("x", "y")) get_control(dat, "x") ```

net-accessor function