Get upstream targets from a specified target — tar

Find all targets that a given target depends on, either directly or indirectly. This is useful for understanding the dependencies and requirements of a target.

Usage

tar_upstream(target_name, immediate = FALSE)

Arguments

target_name: Symbol or character. Name of the target to find upstream targets from.
immediate: Logical. If `TRUE`, return only first-degree dependencies (targets that `target_name` directly depends on). If `FALSE` (default), return all upstream targets, including indirect dependencies.

Value

Character vector of upstream target names (excluding the target itself). Returns an empty character vector if there are no upstream targets (i.e., the target has no dependencies).

Details

This function is the inverse of [tar_downstream()]. While `tar_downstream()` shows what depends on a target, `tar_upstream()` shows what a target depends on.

This function requires the `igraph` package, which is listed in Imports. It queries the current targets pipeline via `targets::tar_network()` and traverses the dependency graph to find all targets that the specified target depends on.

Examples

if (FALSE) { # \dontrun{
# After tar_make(), show what 'final_output' depends on
tar_upstream(final_output)

# Only direct dependencies
tar_upstream("analysis", immediate = TRUE)
} # }