I am having a hard time manipulating my data to be useful in a bar chart.
This is the data is ended up with after mapping it with only the properties i need:
const data = [
{
date: "2021-10-10",
serialNumber: "4A6211B92417A7DB"
},
{
date: "2021-10-11",
serialNumber: "5B6211B92417A7DB"
},
{
date: "2021-10-12",
serialNumber: "5B6211B92417A7DB"
},
{
date: "2021-10-12",
serialNumber: "4A6211B92417A7DB"
},
{
date: "2021-10-12",
serialNumber: "4A6211B92417A7DB"
},
{
date: "2021-10-12",
serialNumber: "4A6211B92417A7DB"
}
];
What i want to have is the following: a count of the duplicates based on the date per serialNumber. It would look like this:
const solution = [
{
serialNumber: "4A6211B92417A7DB",
count: 3,
date: "2021-10-12",
},
{
serialNumber: "5B6211B92417A7DB",
count: 1,
date: "2021-10-12",
},
{
serialNumber: "5B6211B92417A7DB",
count: 1,
date: "2021-10-11",
},
{
serialNumber: "5B6211B92417A7DB",
count: 1,
date: "2021-10-10",
},
]
What i came up with was the following:
array.forEach(function(obj: any) {
const key = JSON.stringify(obj.serialNumber)
counts[key] = (counts[key] || 0) + 1
});
but then it only count them based on 1 parameter and i also need the count per date aswel. How do you do this?
You can use a 'group-by' with a composite key formed of the date and serial number. Here using a for..of loop to accumulate into an object, creating the composite key using a template literal and then assigning the Object.values() as the result.
const data = [{ date: '2021-10-10', serialNumber: '4A6211B92417A7DB', }, { date: '2021-10-11', serialNumber: '5B6211B92417A7DB', }, { date: '2021-10-12', serialNumber: '5B6211B92417A7DB', }, { date: '2021-10-12', serialNumber: '4A6211B92417A7DB', }, { date: '2021-10-12', serialNumber: '4A6211B92417A7DB', }, { date: '2021-10-12', serialNumber: '4A6211B92417A7DB', },];
const counts = {};
for (const datum of data) {
const k = `${datum.date}_${datum.serialNumber}`;
// using OR short circuit
(counts[k] || (counts[k] = { ...datum, count: 0 })).count += 1;
// alternativley with logical nullish assignment if available
//(counts[k] ??= { ...datum, count: 0 }).count += 1;
}
const result = Object.values(counts);
console.log(result);