Initialize a Multi-Source Flow

Entry point for flows that begin with multiple parallel identification streams, such as systematic review diagrams. Each named argument defines a source group (column). Individual databases or registers within each group are listed as sub-items inside a single box, mirroring the format of exclusion reasons.

Usage

sources(..., headers = NULL)

Arguments

...

Named integer vectors specifying sources. Each argument name identifies a group and its named elements are individual sources (e.g., databases = c("PubMed" = 1234, "Embase" = 567)). Scalar named arguments are treated as individual sources in a single default group.

headers

Named character vector mapping group names to column header labels. For example, headers = c(databases = "Databases and registers", other = "Other methods"). If omitted, the argument names are title-cased and used as headers.

Value

An object of class "selecta" with a sources step pre-loaded. The total starting count is the sum of all source counts across all groups.

Details

sources() initializes a multi-source flow of the kind used in the identification stage of systematic-review diagrams (PRISMA, MOOSE), where records arrive from several origins and are pooled. Counts are supplied as named numeric values; passing named vectors instead of scalars groups the sources into labeled columns, and at most three groups are supported, matching the standard PRISMA layout. A sources() flow is operated in manual mode and is normally followed by combine() to merge the streams into a single downstream node. For a conventional single-entry study, use enroll() instead.

See also

enroll for single-source entry, combine to merge parallel streams into a single flow

Other flow construction functions: assess(), combine(), endpoint(), enroll(), exclude(), phase(), stratify()

Examples

# Simple multi-source (one column, no header)
sources(PubMed = 1234, Embase = 567, CENTRAL = 89)
#> selecta flow (manual mode)
#>   Starting N: 1.890
#>   Steps: 1
#>   [1] sources:
#>          PubMed (n = 1.234)
#>          Embase (n = 567)
#>          CENTRAL (n = 89)

# Grouped sources (PRISMA two-column layout)
sources(
  databases = c("PubMed" = 1234, "Embase" = 567, "CENTRAL" = 89),
  other     = c("Citation search" = 55, "Websites" = 34)
)
#> selecta flow (manual mode)
#>   Starting N: 1.979
#>   Steps: 1
#>   [1] sources (Databases):
#>          PubMed (n = 1.234)
#>          Embase (n = 567)
#>          CENTRAL (n = 89)
#>   [1] sources (Other):
#>          Citation search (n = 55)
#>          Websites (n = 34)

# Three columns with custom headers
sources(
  previous  = c("Previous review" = 12, "Previous reports" = 15),
  databases = c("PubMed" = 1234, "Embase" = 567, "CENTRAL" = 89),
  other     = c("Citation search" = 55, "Websites" = 34),
  headers   = c(previous  = "Previous studies",
                databases = "Databases and registers",
                other     = "Other methods")
) |>
  combine("Records after deduplication") |>
  exclude("Records removed", n = 352, show_count = FALSE,
          reasons = c("Duplicates" = 340,
                      "Marked ineligible" = 12))
#> selecta flow (manual mode)
#>   Starting N: 2.006
#>   Steps: 3
#>   [1] sources (Previous studies):
#>          Previous review (n = 12)
#>          Previous reports (n = 15)
#>   [1] sources (Databases and registers):
#>          PubMed (n = 1.234)
#>          Embase (n = 567)
#>          CENTRAL (n = 89)
#>   [1] sources (Other methods):
#>          Citation search (n = 55)
#>          Websites (n = 34)
#>   [2] combine: "Records after deduplication"
#>   [3] exclude: "Records removed" (n = 352)
#>          • Duplicates = 340
#>          • Marked ineligible = 12
#>