I tried searching through previous questions but couldn't find the answer so here's a very generic question.
I have a multidimensional array like so:
array = [
[ "1", "2013-14" , 1234],
[ "2", "2013-14", 2345],
[ "1", "2014-15" , 5234],
[ "2", "2014-15", 7345],
]
I am trying to change it to a nested object based on the year:
obj = {
"2013-14": { 1: "1234", 2: "2345" },
"2014-15": { 2: "5234", 2: "7345" }
}
I tried this, which gave a similar but wrong solution:
let obj = {}
for (let i = 0; i < array.length; i++) {
obj[array[i][1]] = {
[array[i][0]]: array[i][2]
}
}
the solution I got:
obj = {
"2013-14": { 2: "2345" },
"2014-15": { 2: "7345" }
}
so instead of concatenating values under the same key, which in this case is the year, it is overriding it and saving the last one
You need to respect the object for ech date.
const
array = [["1", "2013-14", 1234], ["2", "2013-14", 2345], ["1", "2014-15", 5234], ["2", "2014-15", 7345]],
obj = {};
for (let i = 0; i < array.length; i++) {
obj[array[i][1]] ??= {};
obj[array[i][1]][array[i][0]] = array[i][2];
}
console.log(obj);A shorter approach with destructuring
const
array = [["1", "2013-14", 1234], ["2", "2013-14", 2345], ["1", "2014-15", 5234], ["2", "2014-15", 7345]],
obj = {};
for (const [inner, outer, value] of array) {
obj[outer] ??= {};
obj[outer][inner] = value;
}
console.log(obj);The problem I think is that you're trying to access objects within the key you just initialised. The code is writing the data you wanted but since you're accessing the same key multiple times, the data is being overwritten.
I tried the following approach in Python and it worked :
data = [
[ "1", "2013-14" , 1234],
[ "2", "2013-14", 2345],
[ "1", "2014-15" , 5234],
[ "2", "2014-15", 7345],
]
# EXTRACT KEYS TO INITIALIZE OBJECT AND INSERT VALUES LATER
keys=[]
for i in data :
if i[1] not in keys:
keys.append(i[1])
parsed_obj = {k:{} for k in keys}
for i in data :
parsed_obj[i[1]][i[0]] = i[2]
print(parsed_obj)
Output :
{'2013-14': {'1': 1234, '2': 2345}, '2014-15': {'1': 5234, '2': 7345}}
I know it's not ideal but maybe someone can help you translate this into JS.
you can use spread operator {...} to concat it.
Here is the code:
var array = [
["1", "2013-14", 1234],
["2", "2013-14", 2345],
["1", "2014-15", 5234],
["2", "2014-15", 7345],
];
let obj = {};
for (let i = 0; i < array.length; i++) {
obj[array[i][1]] = { ...obj[array[i][1]], [array[i][0]]: array[i][2] };
}
console.log(obj);