seed_prior: Seed Teleport Prior for Personalized PageRank

In pagerankr: Modular Toolkit for PageRank Calculation

Seed Teleport Prior for Personalized PageRank

Description

Build a teleport prior (a 'prior_df') concentrated on a set of **seed** pages. A seed prior is the teleportation vector that biases the random surfer toward the seeds instead of jumping uniformly, and it is the single ingredient shared by the seed-biased members of the PageRank family: [trustrank()] (trusted seeds) and [topic_feeder_pagerank()] (a target cluster) both build one and hand it to [pagerank()].

'seed_prior()' is **orientation-agnostic**: it does nothing but turn a seed set into a 'url'/'weight' prior. Whether teleport mass then flows *outward* from the seeds (trust) or is accumulated by pages that *point into* the seeds (feeders) is a property of the **graph**, chosen by the caller — not of this builder. [trustrank()] runs the prior on the forward graph; [topic_feeder_pagerank()] runs the identical prior on the reversed graph ('pagerank(reverse = TRUE)'). That is precisely why one builder serves both: the direction lives in the wrapper, not in the prior.

For the multi-topic case ([topic_sensitive_pagerank()]) the prior is built internally per topic from a named list; 'seed_prior()' covers the single-seed-set case that the two convenience wrappers share.

Usage

seed_prior(
  seeds,
  seed_weight = NULL,
  seed_url_col = "url",
  seed_weight_col = "weight"
)

Arguments

seeds	The seed set. Either a character vector of seed URLs (each gets equal weight unless 'seed_weight' is given), or a data frame with a URL column and a numeric weight column (see 'seed_url_col' / 'seed_weight_col') for unequal emphasis.
seed_weight	Optional numeric weight for a character-vector 'seeds': either one value per seed or a single value recycled to all seeds. Ignored when 'seeds' is a data frame. Default 'NULL' (every seed weight '1', i.e. a uniform distribution over the seed set).
seed_url_col, seed_weight_col	Column names used when 'seeds' is a data frame. Defaults '"url"' / '"weight"'. Ignored for a character vector.

Details

Seed weights are an **additive teleport budget**: when two seed URLs fold onto the same vertex (redirect / canonical variants) their weights sum, exactly as the [pagerank()] / [align_prior_to_vertices()] prior contract specifies. Equal weights give a uniform distribution over the seed set; unequal weights express graded emphasis (graded trust for [trustrank()], graded cluster importance for [topic_feeder_pagerank()]).

Value

A data frame with 'url' and 'weight' columns, suitable as the 'prior_df' argument to [pagerank()].

See Also

[trustrank()], [topic_feeder_pagerank()], [topic_sensitive_pagerank()], [pagerank()], [align_prior_to_vertices()]

Examples

# A trusted-seed prior for TrustRank: run on the FORWARD graph, trust flows
# outward from the seeds.
prior <- seed_prior(c("/", "/hub"))
prior

edges <- data.frame(
  from = c("/", "/hub", "/feeder"),
  to = c("/hub", "/ai", "/ai")
)
pagerank(edges, prior_df = prior, clean_edge_urls = FALSE)

# The SAME builder makes a cluster prior for feeder PageRank; the only
# difference is the graph orientation you run it on (reverse = TRUE).
cluster <- seed_prior("/ai")
pagerank(edges, prior_df = cluster, reverse = TRUE, clean_edge_urls = FALSE)

# Graded emphasis via a data frame.
seed_prior(data.frame(url = c("/a", "/b"), weight = c(3, 1)))

pagerankr documentation built on Oct. 1, 2026, 5:09 p.m.