The d3.group documentation says:
d3.group(iterable, ...keys)
For example, if I have the following:
data = [
{name: "jim", amount: "34.0", date: "11/12/2015"},
{name: "carl", amount: "120.11", date: "11/12/2015"},
{name: "stacy", amount: "12.01", date: "01/04/2016"},
{name: "stacy", amount: "34.05", date: "01/04/2016"}
]
But instead of:
d3.group(data, d => d.name, d => d.date)
I want to do something like:
d3.group(data, ['name', 'date'])
How should I do it? The reason is that I might not know the keys in advance and will have to do the grouping programatically.
Thank you!
...keys can be a map which itself returns a function e.g. ...keys.map(k => d => d[k]).
See below - this uses groups instead of group as it's readable in the console output - but this works for group as well.
const data = [
{name: "jim", amount: "34.0", date: "11/12/2015"},
{name: "carl", amount: "120.11", date: "11/12/2015"},
{name: "stacy", amount: "12.01", date: "01/04/2016"},
{name: "stacy", amount: "34.05", date: "01/04/2016"}
];
const keys = ["name", "date"];
const grps = d3.groups(
data,
...keys.map(k => d => d[k])
);
console.log(grps);<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/7.6.1/d3.min.js"></script>