From f40da8504eeff9ff9413bd2196fcb84e5ee6c5eb Mon Sep 17 00:00:00 2001
From: yukako <114702943+y-tom@users.noreply.github.com>
Date: Sat, 28 Jun 2025 15:06:09 +0900
Subject: [PATCH 1/2] =?UTF-8?q?=E3=83=A9=E3=83=B3=E3=82=AD=E3=83=B3?=
 =?UTF-8?q?=E3=82=B0=E3=81=AE=E5=AE=9F=E8=A3=85=E5=AE=8C=E4=BA=86?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 app.js | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/app.js b/app.js
index ad9a93a..8b695e3 100644
--- a/app.js
+++ b/app.js
@@ -1 +1,43 @@
 'use strict';
+const fs = require('node:fs');
+const readline = require('node:readline');
+const rs = fs.createReadStream('./popu-pref.csv');
+const rl = readline.createInterface({ input: rs });
+const prefectureDataMap = new Map(); // key: 都道府県 value: 集計データのオブジェクト
+rl.on('line', lineString => {
+  const columns = lineString.split(',');
+  const year = parseInt(columns[0]);
+  const prefecture = columns[1];
+  const popu = parseInt(columns[3]);
+  if (year === 2016 || year === 2021) {
+    let value = null;
+    if (prefectureDataMap.has(prefecture)) {
+      value = prefectureDataMap.get(prefecture);
+    } else {
+      value = {
+        before: 0,
+        after: 0,
+        change: null
+      };
+    }
+    if (year === 2016) {
+      value.before = popu;
+    }
+    if (year === 2021) {
+      value.after = popu;
+    }
+    prefectureDataMap.set(prefecture, value);
+  }
+});
+rl.on('close', () => {
+  for (const [key, value] of prefectureDataMap) {
+    value.change = value.after / value.before;
+  }
+    const rankingArray = Array.from(prefectureDataMap).sort((pair1, pair2) => {
+    return pair2[1].change - pair1[1].change;
+  });
+    const rankingStrings = rankingArray.map(([key, value]) => {
+    return `${key}: ${value.before}=>${value.after} 変化率: ${value.change}`;
+  });
+  console.log(rankingStrings);
+});

From 175a6060332c09c02d6eb42b74a38950e0fbf478 Mon Sep 17 00:00:00 2001
From: yukako <114702943+y-tom@users.noreply.github.com>
Date: Sat, 28 Jun 2025 15:16:01 +0900
Subject: [PATCH 2/2] =?UTF-8?q?=E6=B8=9B=E5=B0=91=E3=83=A9=E3=83=B3?=
 =?UTF-8?q?=E3=82=AD=E3=83=B3=E3=82=B0=E3=81=AE=E5=AE=9F=E8=A3=85?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 app.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/app.js b/app.js
index 8b695e3..9aa480d 100644
--- a/app.js
+++ b/app.js
@@ -34,10 +34,10 @@ rl.on('close', () => {
     value.change = value.after / value.before;
   }
     const rankingArray = Array.from(prefectureDataMap).sort((pair1, pair2) => {
-    return pair2[1].change - pair1[1].change;
+    return pair1[1].change - pair2[1].change;
   });
-    const rankingStrings = rankingArray.map(([key, value]) => {
-    return `${key}: ${value.before}=>${value.after} 変化率: ${value.change}`;
+      const rankingStrings = rankingArray.map(([key, value], i) => {
+    return `${i + 1}位 ${key}: ${value.before}=>${value.after} 変化率: ${value.change}`;
   });
   console.log(rankingStrings);
 });