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2010 年から 2015 年にかけて 15〜19 歳の人が減った割合の都道府県ランキング #431

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50 changes: 50 additions & 0 deletions app.js
Original file line number Diff line number Diff line change
@@ -1 +1,51 @@
'use strict';
const fs = require('fs');
const readline =require('readline');
const rs =fs.createReadStream('./popu-pref.csv');
const rl =readline.createInterface({input: rs, output: {} });
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===2010 ||year===2015){

let value =prefectureDataMap.get(prefecture);
if(!value){
value ={
popu10: 0,
popu15: 0,
change: null
};
}
if(year===2010){
value.popu10 =popu;
}
if(year===2015){
value.popu15 =popu;
}
prefectureDataMap.set(prefecture, value);
}
});
rl.on('close', () => {
for(let [key, value] of prefectureDataMap){
value.change =value.popu15 / value.popu10;
}

const rankingArray =Array.from(prefectureDataMap).sort((pair1, pair2) => {
return pair1[1].change - pair2[1].change;
});
const rankingString =rankingArray.map(([key, value],i) =>{
return ((i+1) + '位: '+key + ': ' + value.popu10 + '=>' + value.popu15 + ' 変化率: ' + value.change);
});

console.log(rankingString);
});