doc: simple examples and how to get ranked array of sentences

README.md

@@ -5,16 +5,44 @@
 [![SwiftFormat](https://img.shields.io/badge/SwfitFormat-enabled-A166E6)](https://github.com/nicklockwood/SwiftFormat)
 ![GitHub Actions CI](https://github.com/jhrcook/TextRank/workflows/GitHub%20Actions%20CI/badge.svg)
 
-A Swift package that implements the ['TextRank' algorithm](https://web.eecs.umich.edu/~mihalcea/papers/mihalcea.emnlp04.pdf) for summarization and keyword extraction.
-It is based off of the [original Python implementation](https://github.com/summanlp/textrank).
+A Swift package that implements the ['TextRank' algorithm](https://web.eecs.umich.edu/~mihalcea/papers/mihalcea.emnlp04.pdf) for summarization.
+This algorithm uses the [PageRank (PR) algorithm](https://en.wikipedia.org/wiki/PageRank) to rank nodes by centrality in a weighted, undirected network where the nodes are sentences and edges indicate the degree of similarity of two sentences.
 
 *This package is functional, but young. Please open an issue if you find any bugs or have any feature requests.*
 
 Stop words were acquired from [Ranks NL](https://www.ranks.nl/stopwords).
 Please open an issue to request additional language support.
 
+### Example
+
+```swift
+import TextRank
+
+let textRank = TextRank(text: myParagraph)
+let rankedResults = textRank.runPageRank()
+```
+
+The `rankedResults` is a `TextGraph.PageRankResult` struct with three properties:
+
+1. `didConverge`: whether or not the PR algorithm converged
+2. `iterations`: the number of iterations required for the PR algorithm to converge
+3. `results`: a `TextGraph.NodeList` which is a type alias for `[Sentence: Float]` that holds the final rankings from the PR algorithm
+
+The `PageRankResult.results` object holds the final node list after running PR.
+Under the hood, it is a dictionary mapping each sentence to a rank.
+The keys are of type `Sentence` which has properties for the original sentence `text` and the set of words in the sentence `words`.
+Below is an example of how to obtain an array of sentences sorted by their rankings in decreasing order.
+
+```swift
+let sortedSentences: [String] = rankedResults
+	.results
+	.sorted { $0.value < $1.value }
+	.map { $0.key }
+```
+
 ---
 
 ### Similar projects
 
+This code base is based off of the [original Python implementation](https://github.com/summanlp/textrank).
 These is another Swift package, ['SwiftTextRank'](https://github.com/goncharik/SwiftTextRank) that implements this algorithm.