tar_igraph: Get the igraph.
In targets: Dynamic Function-Oriented 'Make'-Like Declarative Pipelines

tar_igraph

R Documentation

Get the igraph.

Description

Return an igraph object with the dependency graph of the pipeline.

Usage

tar_igraph(
  targets_only = FALSE,
  callr_function = callr::r,
  callr_arguments = targets::tar_callr_args_default(callr_function),
  envir = parent.frame(),
  script = targets::tar_config_get("script")
)

Arguments

`targets_only`	`TRUE` to restrict the output to just the actual targets in the pipeline, `FALSE` to include imported global functions and objects as well.
`callr_function`	A function from `callr` to start a fresh clean R process to do the work. Set to `NULL` to run in the current session instead of an external process (but restart your R session just before you do in order to clear debris out of the global environment). `callr_function` needs to be `NULL` for interactive debugging, e.g. `tar_option_set(debug = "your_target")`. However, `callr_function` should not be `NULL` for serious reproducible work.
`callr_arguments`	A list of arguments to `callr_function`.
`envir`	An environment, where to run the target R script (default: `⁠_targets.R⁠`) if `callr_function` is `NULL`. Ignored if `callr_function` is anything other than `NULL`. `callr_function` should only be `NULL` for debugging and testing purposes, not for serious runs of a pipeline, etc. The `envir` argument of `tar_make()` and related functions always overrides the current value of `tar_option_get("envir")` in the current R session just before running the target script file, so whenever you need to set an alternative `envir`, you should always set it with `tar_option_set()` from within the target script file. In other words, if you call `tar_option_set(envir = envir1)` in an interactive session and then `tar_make(envir = envir2, callr_function = NULL)`, then `envir2` will be used.
`script`	Character of length 1, path to the target script file. Defaults to `tar_config_get("script")`, which in turn defaults to `⁠_targets.R⁠`. When you set this argument, the value of `tar_config_get("script")` is temporarily changed for the current function call. See `tar_script()`, `tar_config_get()`, and `tar_config_set()` for details about the target script file and how to set it persistently for a project.

Details

If you have igraph >= 2.2.0 installed, then you can debug cycles in your pipeline by running igraph::find_cycle(tar_igraph()). This helps detect cycles in the dependency graph of the pipeline. A cycle happens when a target directly or indirectly depends on itself, which is not allowed. igraph::find_cycle() returns a character vector of the names of the targets and objects involved in the cycle (if a cycle exists).

Value

An igraph object with the dependency graph.

Examples

if (identical(Sys.getenv("TAR_EXAMPLES"), "true")) { # for CRAN
  tar_dir({ # tar_dir() runs code from a temp dir for CRAN.
    tar_script(
      list(
        tar_target(x, 1),
        tar_target(y, 2)
      ),
      ask = FALSE
    )
    tar_igraph()
  })
}

targets documentation built on Feb. 10, 2026, 1:07 a.m.