Chartjs-Count the duplicates in a string array using React JS

by

1👍

✅

This could be done as follows:

const res = {
  data: [
    { time: 1, destination: 'A'},
    { time: 3, destination: 'A'},
    { time: 2, destination: 'B'}    
  ]
};

let tmp4 = [];
res.data.map((o, i) => {
  const existing = tmp4.find(e => e.destination == o.destination);
  if (existing) {
    existing.time += o.time;
  } else {
    tmp4.push({time: o.time, destination: o.destination});
  }
})

this.setState({
  data4: tmp.map(o => o.time);
  labels4: tmp.map(o => o.destination);
});

Above code could further be optimized by using Array.reduce() instead of Array.map().

1👍

I would make the code more efficient. Instead of dataArrayY4 being an array, I would make it an object that has a key of value and the number of occurrence of each value. This way, you can count all the number of occurrences of the all items in res.data

const dataArrayY4 = {};
res.data.map(item => {
     dataArrayY4[item.destination] = (dataArrayY4[item.destination] || 0) + 1
 })
 
const dataArrayX4 = []
 res.data.forEach(item => {
    dataArrayX4.push(item.destination)
 })
this.setState({
    data4: dataArrayY4,
      labels4: dataArrayX4,
 });

Then if you want to look for the occurrence of a particular value you
use this eg. Sri Lanka

this.state.data4['Sri Lanka']

Leave a comment