Is there a better way to convert
["88 99", "20 99", "12 12"]
to a hashmap in the form
{"88": 1, "99": 2, "20": 1, "12": 1}
Using map or reduce?
Where in this case, a string with duplicate numbers only gets increases it's count by 1.
Currently I'm converting the above array into a 2d array using .split(' ')
and iterating over that 2d array in another for loop as so:
var counts = {}
for (let i = 0; i < logs.length; i++){
let ack = logs[i].split(' ');
if(ack[0]==ack[1]){
counts[ack[0]] = counts[ack[0]] ? counts[ack[0]] + 1 : 1;
}
else{
for(let j= 0; j < 2; j++){
counts[ack[j]] = counts[ack[j]] ? counts[ack[j]] + 1 : 1;
}
}
}
First I group by numbers, summing the appearances of each. This is using the reduce part. That's it. I used adaption of method by https://stackoverflow.com/a/62031473/3807365
var arr = ["88 99", "20 99", "12 12"]
var step1 = arr.reduce(function(agg, pair) {
pair.split(" ").forEach(function(item) {
agg[item] = (agg[item] || 0) + 1
})
return agg;
}, {})
console.log(step1)Yes. I'm assuming you want to write in a functional style, so I'm not worrying about efficiency, etc.
You can collapse this into a hairy one-liner but I wrote the intermediate steps and output them for illustration.
const input = ["88 99", "20 99", "12 12"];
const split = input.map( (string) => string.split(" ") );
console.log("split: " + JSON.stringify(split));
const flattened = split.reduce( (acc,array) => acc = acc.concat(array), []);
console.log("flattened: " + JSON.stringify(flattened));
const output = flattened.reduce( (byKey, item) => {
if (!byKey[item]) byKey[item] = 0;
byKey[item]++;
return byKey;
}, {});
console.log(JSON.stringify(output))