How can I switch from array to object data type in pipeline using ramda's reduce in point-free style?
I would like to achieve this:
(nodes) => nodes.reduce((acc, node: any) => {
acc[node.id] = {
out: node.outgoing_explicit,
in: node.incoming_explicit
};
return acc;
}, {})
Index the nodes by id, and the map them and use R.applySpec to change to the in/out format:
const { pipe, indexBy, map, applySpec, prop } = R
const fn = pipe(
indexBy(prop('id')),
map(applySpec({
out: prop('outgoing_explicit'),
in: prop('incoming_explicit'),
}))
)
const nodes = [{ id: 1, outgoing_explicit: 'abc1', incoming_explicit: 'xyz1' }, { id: 2, outgoing_explicit: 'abc2', incoming_explicit: 'xyz2' }, { id: 3, outgoing_explicit: 'abc3', incoming_explicit: 'xyz3' }]
const result = fn(nodes)
console.log(result)<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.min.js" integrity="sha512-rZHvUXcc1zWKsxm7rJ8lVQuIr1oOmm7cShlvpV0gWf0RvbcJN6x96al/Rp2L2BI4a4ZkT2/YfVe/8YvB2UHzQw==" crossorigin="anonymous"></script>this could also be a solution:
const spec = {
in: R.prop('incoming_explicit'),
out: R.prop('outgoing_explicit'),
}
const fn = R.reduceBy(
R.flip(R.applySpec(spec)),
null,
R.prop('id'),
);
const data = [
{ id: 'a', incoming_explicit: 'Hello', outgoing_explicit: 'World' },
{ id: 'b', incoming_explicit: 'Hello', outgoing_explicit: 'Galaxy' },
{ id: 'c', incoming_explicit: 'Hello', outgoing_explicit: 'Universe' },
{ id: 'd', incoming_explicit: 'Hello', outgoing_explicit: 'Dimension' },
];
console.log(
fn(data),
);<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.js" integrity="sha512-3sdB9mAxNh2MIo6YkY05uY1qjkywAlDfCf5u1cSotv6k9CZUSyHVf4BJSpTYgla+YHLaHG8LUpqV7MHctlYzlw==" crossorigin="anonymous"></script>The solutions involving applySpec are probably best, but just for variety, here's an alternative:
const convert = pipe (
map (juxt ([prop('id'), props(['incoming_explicit', 'outgoing_explicit'])])),
fromPairs,
map (zipObj (['in', 'out']))
)
const nodes = [{id: 'foo', outgoing_explicit: 43, incoming_explicit: 42}, {id: 'bar', outgoing_explicit: 20, incoming_explicit: 10}, {id: 'baz', outgoing_explicit: 309, incoming_explicit: 8675}]
console .log (convert (nodes))<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.min.js"></script>
<script>const {pipe, map, juxt, prop, props, fromPairs, zipObj} = R </script>`juxt' is a bit of an oddball function. It works like this:
juxt([f, g, h, ...]) //=> (a, b, ...) -> [f(a, b, ...), g(a, b, ...), h(a, b, ...), ...]
