I am working in Javascript with a .dat file with different data about English Soccer teams. I was able to obtain a Json that I transform in this array:
[{"team":"Arsenal","f":"79","a":"36"},
{"team":"Liverpool","f":"67","a":"30"},
{"team":"Manchester_U","f":"87","a":"45"},
{"team":"Newcastle","f":"74","a":"52"},
{"team":"Leeds","f":"53","a":"37"},
{"team":"Chelsea","f":"66","a":"38"},
{"team":"West_Ham","f":"48","a":"57"},
{"team":"Aston_Villa","f":"46","a":"47"},
{"team":"Tottenham","f":"49","a":"53"},
{"team":"Blackburn","f":"55","a":"51"},
{"team":"Southampton","f":"46","a":"54"},
{"team":"Middlesbrough","f":"35","a":"47"},
{"team":"Fulham","f":"36","a":"44"},
{"team":"Charlton","f":"38","a":"49"},
{"team":"Everton","f":"45","a":"57"},
{"team":"Bolton","f":"44","a":"62"},
{"team":"Sunderland","f":"29","a":"51"},
{"team":"Ipswich","f":"41","a":"64"},
{"team":"Derby","f":"33","a":"63"},
{"team":"Leicester","f":"30","a":"64"}]
This array contain the name of different soccer teams and two values: the number of the goal scored (F) and the number of goal conceded (A) by every team. I have to parse this Array to make the following operations:
- Add to the array (for very team) the value the difference between "a" and "f";
- Return the name of the team with the least difference between goals scored and conceded.
But I don't know how.
I arrived only to this point:
const myFrom = document.getElementById("myForm");
const datFile = document.getElementById("datFile");
function fileToArray(text) {
const lines = text.split(/\n/); // split on \n
const header = lines[0].trim().split(/\s /); // split on whitespace after trimming
return [...lines.slice(1).map(line => {
// ignore the number and the dash
const [number, team, p, w, l, d, f, ignore2, a, pts] = line.trim().split(/\s /);
let values={team, f, a};
return values;
})]
}
myForm.addEventListener("submit", function (e) {
e.preventDefault();
console.log("Form submitted");
const input = datFile.files[0];
const reader = new FileReader();
reader.onload = function (e){
const text= e.target.result;
const data = fileToArray(text);
const arr1 = data.slice(0,17);
const arr2 = data.slice(18,21);
let myArray = arr1.concat(arr2);
let myJSON = JSON.stringify(myArray);
let obj=JSON.parse(myJSON);
}
reader.readAsText(input);
}); <form id="myForm">
<input type="file" id="datFile" accept=".dat" />
<br />
<input type="submit" value="Submit" />
</form>At this point I am stopped.
CodePudding user response：
Thought these two operation can be done together for clean writing you can do the following.
map to add the difference between the two property in a new property called d
using Math.abs to keep the difference positive.
let teams = [{"team":"Arsenal","f":"79","a":"36"},
{"team":"Liverpool","f":"67","a":"30"},
{"team":"Manchester_U","f":"87","a":"45"},
{"team":"Newcastle","f":"74","a":"52"},
{"team":"Leeds","f":"53","a":"37"},
{"team":"Chelsea","f":"66","a":"38"},
{"team":"West_Ham","f":"48","a":"57"},
{"team":"Aston_Villa","f":"46","a":"47"},
{"team":"Tottenham","f":"49","a":"53"},
{"team":"Blackburn","f":"55","a":"51"},
{"team":"Southampton","f":"46","a":"54"},
{"team":"Middlesbrough","f":"35","a":"47"},
{"team":"Fulham","f":"36","a":"44"},
{"team":"Charlton","f":"38","a":"49"},
{"team":"Everton","f":"45","a":"57"},
{"team":"Bolton","f":"44","a":"62"},
{"team":"Sunderland","f":"29","a":"51"},
{"team":"Ipswich","f":"41","a":"64"},
{"team":"Derby","f":"33","a":"63"},
{"team":"Leicester","f":"30","a":"64"}];
teams.map((t) => t['d'] = Math.abs(t.f - t.a))
console.log(teams);To reduce to the team that has the lowest difference you can use the below code with reduce
let teams = [{"team":"Arsenal","f":"79","a":"36"},
{"team":"Liverpool","f":"67","a":"30"},
{"team":"Manchester_U","f":"87","a":"45"},
{"team":"Newcastle","f":"74","a":"52"},
{"team":"Leeds","f":"53","a":"37"},
{"team":"Chelsea","f":"66","a":"38"},
{"team":"West_Ham","f":"48","a":"57"},
{"team":"Aston_Villa","f":"46","a":"47"},
{"team":"Tottenham","f":"49","a":"53"},
{"team":"Blackburn","f":"55","a":"51"},
{"team":"Southampton","f":"46","a":"54"},
{"team":"Middlesbrough","f":"35","a":"47"},
{"team":"Fulham","f":"36","a":"44"},
{"team":"Charlton","f":"38","a":"49"},
{"team":"Everton","f":"45","a":"57"},
{"team":"Bolton","f":"44","a":"62"},
{"team":"Sunderland","f":"29","a":"51"},
{"team":"Ipswich","f":"41","a":"64"},
{"team":"Derby","f":"33","a":"63"},
{"team":"Leicester","f":"30","a":"64"}];
teams.map((t) => t['d'] = Math.abs(t.f - t.a))
// now finding the team with the lowsest
let result = teams.reduce((teamA,teamB) => teamA.d > teamB.d? teamB: teamA );
console.log(result);CodePudding user response：
Both using loop (e.g. for...of ) or array methods (e.g. map for the part 1 and filter for part 2) are valid approach.
I personally prefer loop because it is easier to read and debug and you can combine both steps into one loop. something like:
// use the first element as starter then update in the loop
let leastDiff = Math.abs(myArray[0].f - myArray[0].a);
let bestTeam = myArray[0].team;
for (let item of myArray) {
item.diff = Math.abs(item.f - item.a);
if (item.diff < leastDiff) {
leastDiff = item.diff;
bestTeam = item.team;
}
}
console.log(`Team with least difference is ${bestTeam} with ${leastDiff} goal difference`);
CodePudding user response：
A combination of map and reduce will do:
const teams= [{"team":"Arsenal","f":"79","a":"36"}, {"team":"Liverpool","f":"67","a":"30"}, {"team":"Manchester_U","f":"87","a":"45"}, {"team":"Newcastle","f":"74","a":"52"}, {"team":"Leeds","f":"53","a":"37"}, {"team":"Chelsea","f":"66","a":"38"}, {"team":"West_Ham","f":"48","a":"57"}, {"team":"Aston_Villa","f":"46","a":"47"}, {"team":"Tottenham","f":"49","a":"53"}, {"team":"Blackburn","f":"55","a":"51"}, {"team":"Southampton","f":"46","a":"54"}, {"team":"Middlesbrough","f":"35","a":"47"}, {"team":"Fulham","f":"36","a":"44"}, {"team":"Charlton","f":"38","a":"49"}, {"team":"Everton","f":"45","a":"57"}, {"team":"Bolton","f":"44","a":"62"}, {"team":"Sunderland","f":"29","a":"51"}, {"team":"Ipswich","f":"41","a":"64"}, {"team":"Derby","f":"33","a":"63"}, {"team":"Leicester","f":"30","a":"64"}]
let diff=Infinity;
console.log(
teams.map((t)=>(t.d=t.a-t.f, t))
.reduce((a,c)=>Math.abs(c.d)<=diff?(diff=Math.abs(c.d), c.team): a,'')
);