I kinda want to create a feature which is most often known in factories. Kind of rotation system, where people swap their station, while others are on break.
via DragnDrop I create/add/update a Map and convert this map to an array of arrays like this:
let example1 = [
['John', ['99', '1']],
['Jo', ["1", "3"]],
["Alpha", ["99", "4"]],
["Beta", ["3", "2"]],
["Gamma", ["2", "99"]],
["Delta", ["4", "5"]],
["Maria", ["5", "6"]],
["Epsilon", ["6", "99"]],
];
the first number is for the old Position, the second number is for the new position. The number 99 stands for beeing on break. the output for above example should be something like:
outputExample1 = [
["John", "1", "3", "2"],
["Alpha", "4, "5", "6"]
]
so every sequenze and recursion should start with a breaker (=number 99) and end with a breaker. in above example: after placing "john" at station one, it should "search" where the guy/ladie from station 1 is "now". in this example, he is on 3. now search again where the one from statin 3 is now. (=2) ... until the number is 99, which is the case at this example. thats why I started to filter the original array in 'activ'(<99) and 'breakers'(==99). I tried so many ways and fail continously ( while loops ends in an endless loop, outputs which are totally wrong), because i dont find a nice recursion.
Any hints are very preciated
PS: please consider that above array is "finished" to provide a good example and may not be completed on the fly (via drag and drop). Meaning: if I start to drag the sequenze is for sure not completed.
Edit: there will be for sure at least ONE '99'. if not no sequenze and no output. Also there are no duplicates on the 'new position' except 99er. (which are the starters anyway
You could take a sequential approach and visit all nodes in the order, you have. Then take a nested property for the most top items and keep the relation with the nodes. At the end return just top nodes.
If necessary take the entries of the result for an array of key/value pairs.
const
data = [['John', ['99', '1']], ['Jo', ["1", "3"]], ["Alpha", ["99", "4"]], ["Beta", ["3", "2"]], ["Gamma", ["2", "99"]], ["Delta", ["4", "5"]], ["Maria", ["5", "6"]], ["Epsilon", ["6", "99"]]],
relations = data
.reduce((r, [top, [from, to]]) => {
if (to === '99') return r;
if (from === '99') {
r[to] = r.top[top] = [to];
} else {
r[from].push(to);
r[to] = r[from];
}
return r;
}, { top: {} })
.top;
console.log(relations);.as-console-wrapper { max-height: 100% !important; top: 0; }Version without reduce.
const
data = [['John', ['99', '1']], ['Jo', ["1", "3"]], ["Alpha", ["99", "4"]], ["Beta", ["3", "2"]], ["Gamma", ["2", "99"]], ["Delta", ["4", "5"]], ["Maria", ["5", "6"]], ["Epsilon", ["6", "99"]]],
temp = {},
relations = {};
for (const [top, [from, to]] of data) {
if (to === '99') continue;
if (from === '99') {
temp[to] = relations[top] = [to];
} else {
temp[from].push(to);
temp[to] = temp[from];
}
}
console.log(relations);.as-console-wrapper { max-height: 100% !important; top: 0; }The answer from Nina is fine, so long as your data is always sorted as in the example. If not, then this might help:
const cycleUntil = (schedule, x, [_, [f, t]] = schedule .find (([_, [f]]) => x == f)) =>
f == 99 ? [] : [f, ... cycleUntil (schedule, t)]
const transform = (schedule) =>
schedule .filter (([n, [f]]) => f == '99')
.map (([n, [f, t]]) => [n, ... cycleUntil (schedule, t)])
const example1 = [['John', ['99', '1']], ['Jo', ["1", "3"]], ["Alpha", ["99", "4"]], ["Beta", ["3", "2"]], ["Gamma", ["2", "99"]], ["Delta", ["4", "5"]], ["Maria", ["5", "6"]], ["Epsilon", ["6", "99"]] ]
console .log (transform (example1))
const example2 = [...example1, ["Zeta", ["99", "7"]], ["Eta", ["7", "10"]], ["Theta", ["8", "99"]], ["Iota", ["9", "8"]], ["Kappa", ["10", "9"]]]
console .log (transform (example2)).as-console-wrapper {max-height: 100% !important; top: 0}Here our transform function finds all elements that start with '99' and returns the name associated with them alongside the result of calling the cycleUntil function, which takes a station and the entire schedule and returns an array including that station, and, recursively, the element with that to station in its from position.
This will fail if the data is not constructed properly. It would almost certainly need some error-checking to ensure that the data is complete. But I'll leave that as an exercise.