From 5e958cca47fc4ea0a8cb0a0f920c1e6386b0f1f3 Mon Sep 17 00:00:00 2001
From: Colin DAMON <cdamon@ippon.fr>
Date: Mon, 6 Sep 2021 20:18:31 +0200
Subject: [PATCH] Markov chain implementation
---
.gitlab-ci.yml | 1 +
markov-chain/.gitlab-ci.yml | 11 ++
markov-chain/README.md | 9 ++
markov-chain/pom.xml | 29 +++++
.../java/fr/ippon/markov/MarkovChain.java | 39 +++++++
.../src/main/java/fr/ippon/markov/Stat.java | 5 +
.../main/java/fr/ippon/markov/WordStats.java | 28 +++++
.../java/fr/ippon/markov/MarkovChainTest.java | 106 ++++++++++++++++++
readme.md | 1 +
9 files changed, 229 insertions(+)
create mode 100644 markov-chain/.gitlab-ci.yml
create mode 100644 markov-chain/README.md
create mode 100644 markov-chain/pom.xml
create mode 100644 markov-chain/src/main/java/fr/ippon/markov/MarkovChain.java
create mode 100644 markov-chain/src/main/java/fr/ippon/markov/Stat.java
create mode 100644 markov-chain/src/main/java/fr/ippon/markov/WordStats.java
create mode 100644 markov-chain/src/test/java/fr/ippon/markov/MarkovChainTest.java
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0c16d1af..0b825bb3 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -40,3 +40,4 @@ include:
- local: "/java-diamond/.gitlab-ci.yml"
- local: "/diamond-ts/.gitlab-ci.yml"
- local: "/java-memoizers/.gitlab-ci.yml"
+ - local: "/markov-chain/.gitlab-ci.yml"
diff --git a/markov-chain/.gitlab-ci.yml b/markov-chain/.gitlab-ci.yml
new file mode 100644
index 00000000..47fe1677
--- /dev/null
+++ b/markov-chain/.gitlab-ci.yml
@@ -0,0 +1,11 @@
+package-markov-chain:
+ variables:
+ PROJECT_FOLDER: "markov-chain"
+ extends: .java
+ only:
+ refs:
+ - master
+ - merge_requests
+ changes:
+ - ".gitlab-common-ci.yml"
+ - "markov-chain/**/*"
diff --git a/markov-chain/README.md b/markov-chain/README.md
new file mode 100644
index 00000000..ba4c301c
--- /dev/null
+++ b/markov-chain/README.md
@@ -0,0 +1,9 @@
+# Markov Chain
+
+Découverte du kata [Markov Chain](https://codingdojo.org/kata/MarkovChain/)
+
+- **Auteurs** : Anthony REY et Colin DAMON
+- **Date** : 06/09/2021
+- **Langage** : Java
+- **Niveau** : Moyen
+- **Replay** : [Twitch](https://www.twitch.tv/videos/1140906031)
diff --git a/markov-chain/pom.xml b/markov-chain/pom.xml
new file mode 100644
index 00000000..dc530323
--- /dev/null
+++ b/markov-chain/pom.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+
+ <parent>
+ <version>1.0.0</version>
+ <groupId>fr.ippon.kata</groupId>
+ <artifactId>java-parent</artifactId>
+ <relativePath>../java-parent</relativePath>
+ </parent>
+
+ <version>1.0.0-SNAPSHOT</version>
+ <artifactId>markov-chain</artifactId>
+
+ <name>MarkovChain</name>
+
+ <developers>
+ <developer>
+ <email>arey@ippon.fr</email>
+ <name>Anthony REY</name>
+ </developer>
+ <developer>
+ <email>cdamon@ippon.fr</email>
+ <name>Colin DAMON</name>
+ </developer>
+ </developers>
+</project>
diff --git a/markov-chain/src/main/java/fr/ippon/markov/MarkovChain.java b/markov-chain/src/main/java/fr/ippon/markov/MarkovChain.java
new file mode 100644
index 00000000..439277f7
--- /dev/null
+++ b/markov-chain/src/main/java/fr/ippon/markov/MarkovChain.java
@@ -0,0 +1,39 @@
+package fr.ippon.markov;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class MarkovChain {
+
+ private final Map<String, WordStats> stats = new ConcurrentHashMap<>();
+
+ public void learn(String text) {
+ String[] words = text.split(" ");
+ for (int i = 0; i < words.length - 1; i++) {
+ String current = words[i];
+ String next = words[i + 1];
+
+ append(current, next);
+ }
+ }
+
+ private void append(String current, String next) {
+ stats
+ .computeIfAbsent(current.toLowerCase(),
+ this::newWordStats)
+ .add(next);
+ }
+
+ private WordStats newWordStats(String dummy) {
+ return new WordStats();
+ }
+
+ public WordStats stats(String word) {
+ return stats.getOrDefault(word.toLowerCase(),
+ new WordStats());
+ }
+
+ public Map<String, WordStats> stats() {
+ return stats;
+ }
+}
diff --git a/markov-chain/src/main/java/fr/ippon/markov/Stat.java b/markov-chain/src/main/java/fr/ippon/markov/Stat.java
new file mode 100644
index 00000000..92c0afaa
--- /dev/null
+++ b/markov-chain/src/main/java/fr/ippon/markov/Stat.java
@@ -0,0 +1,5 @@
+package fr.ippon.markov;
+
+public record Stat(String word, float percentage) {
+
+}
diff --git a/markov-chain/src/main/java/fr/ippon/markov/WordStats.java b/markov-chain/src/main/java/fr/ippon/markov/WordStats.java
new file mode 100644
index 00000000..a6549397
--- /dev/null
+++ b/markov-chain/src/main/java/fr/ippon/markov/WordStats.java
@@ -0,0 +1,28 @@
+package fr.ippon.markov;
+
+import java.util.Collection;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class WordStats {
+
+ private final AtomicInteger size = new AtomicInteger();
+ private final Map<String, AtomicInteger> stats = new ConcurrentHashMap<>();
+
+ public void add(String word) {
+ size.incrementAndGet();
+ stats.computeIfAbsent(word, key -> new AtomicInteger())
+ .incrementAndGet();
+ }
+
+ public Collection<Stat> get() {
+ return stats.entrySet()
+ .stream()
+ .map(entry -> new Stat(entry.getKey(),
+ entry.getValue()
+ .floatValue() / size.floatValue()))
+ .toList();
+ }
+
+}
diff --git a/markov-chain/src/test/java/fr/ippon/markov/MarkovChainTest.java b/markov-chain/src/test/java/fr/ippon/markov/MarkovChainTest.java
new file mode 100644
index 00000000..8c9ff21c
--- /dev/null
+++ b/markov-chain/src/test/java/fr/ippon/markov/MarkovChainTest.java
@@ -0,0 +1,106 @@
+package fr.ippon.markov;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+class MarkovChainTest {
+ private final MarkovChain markov = new MarkovChain();
+
+ @Test
+ void shouldGetStatsForOneWord() {
+ markov.learn("Les");
+
+ assertThat(markov.stats("Les")
+ .get()).isEmpty();
+ }
+
+ @Test
+ void shoulGetStatsForTwoWords() {
+ markov.learn("Les hommes");
+
+ assertThat(markov.stats("Les")
+ .get()).containsExactly(stat("hommes", 1f));
+ }
+
+ @Test
+ void shoulGetStatsWithMultipleFollowers() {
+ markov.learn("Les hommes les plus grands");
+
+ assertThat(markov.stats("Les")
+ .get()).containsExactly(stat("hommes", 0.5f),
+ new Stat("plus", 0.5f));
+ assertThat(markov.stats("hommes")
+ .get()).containsExactly(stat("les", 1f));
+ }
+
+ @Test
+ void shoulGetStats() {
+ markov.learn("Les hommes les plus grands");
+
+ assertThatStats(markov.stats()).hasWord("les")
+ .withStat("hommes", 0.5f)
+ .withStat("plus", 0.5f)
+ .and()
+ .hasWord("hommes")
+ .withStat("les", 1f);
+ }
+
+ private static Stat stat(String word, float stat) {
+ return new Stat(word, stat);
+ }
+
+ private static StatsAsserter assertThatStats(
+ Map<String, WordStats> stats) {
+ return new StatsAsserter(stats);
+ }
+
+ private static class StatsAsserter {
+
+ private final Map<String, WordStats> stats;
+
+ public StatsAsserter(Map<String, WordStats> stats) {
+ this.stats = stats;
+ }
+
+ public WordStatAsserter hasWord(String word) {
+ assertThat(stats).containsKey(word);
+
+ return new WordStatAsserter(stats.get(word), this);
+ }
+
+ }
+
+ private static class WordStatAsserter {
+
+ private final WordStats wordStats;
+ private final StatsAsserter source;
+
+ public WordStatAsserter(WordStats wordStats,
+ StatsAsserter source) {
+ this.wordStats = wordStats;
+ this.source = source;
+ }
+
+ public WordStatAsserter withStat(String word,
+ float percent) {
+ float result = wordStats.get()
+ .stream()
+ .filter(stat -> stat.word()
+ .equals(word))
+ .findFirst()
+ .orElseThrow(AssertionError::new)
+ .percentage();
+
+ assertThat(result).isEqualTo(percent);
+
+ return this;
+ }
+
+ public StatsAsserter and() {
+ return source;
+ }
+ }
+}
diff --git a/readme.md b/readme.md
index 92959e14..26510f98 100644
--- a/readme.md
+++ b/readme.md
@@ -44,6 +44,7 @@ Un kata de code est un petit exercice pensé pour s'entrainer jusqu'à maitriser
- [Tennis Refactoring kata](/tennis/refactoring)
- [Puzzles](java-puzzles)
- [Diamond](java-diamond)
+- [Markov chain](markov-chain)
### Énervé
--
GitLab