Identification of a Collection of Arrays

Question

Identification of a Collection of Arrays

My JSON data may have different formats. For example, it could look like this:

"coordinates":
  [
    [[100.0,0.0],[101.0,0.0],[101.0,1.0],[100.0,1.0],[100.0,0.0]],
    [[100.2,0.2],[100.8,0.2],[100.8,0.8],[100.2,0.8],[100.2,0.2]]
  ]

This format appears as an array of arrays and needs to be handled differently from something like this:

"coordinates":[30.0,10.0]

I was previously making decisions based on the length of the coordinates array (which is always 2 in these cases). However, I now need to ensure that it's not an array of arrays before taking certain actions.

javascript arrays json

Answer 1

Answer №1

Perhaps you could try implementing it this way?

if (Array.isArray(coordinates)) {
  // check if coordinates is an array
  if (Array.isArray(coordinates[0])) {
    // check if first element in coordinates is also an array
    // handle polyline data
  } else {
    // handle single point data
  }
}

Answer 2

Perhaps you could try implementing it this way?

if (Array.isArray(coordinates)) {
  // check if coordinates is an array
  if (Array.isArray(coordinates[0])) {
    // check if first element in coordinates is also an array
    // handle polyline data
  } else {
    // handle single point data
  }
}

Answer 3

Answer №2

But I want to ensure that it is not an array containing arrays

What if we create a simple check function:

var arr1=[1,2,3,4];
var arr2=[[1],[2]];

function checkArrayForArrays(arr){
    return arr.every(function(item){ return Array.isArray(item); });
}

console.log(checkArrayForArrays(arr1));
console.log(checkArrayForArrays(arr2));

JSBIN for testing. MDN documentation on Array.prototype.every().

Edit: Keep in mind that there may be cases where you have a mix of data types, which would result in false. In such scenarios, using Array.prototype.some() can help.

Answer 4

But I want to ensure that it is not an array containing arrays

What if we create a simple check function:

var arr1=[1,2,3,4];
var arr2=[[1],[2]];

function checkArrayForArrays(arr){
    return arr.every(function(item){ return Array.isArray(item); });
}

console.log(checkArrayForArrays(arr1));
console.log(checkArrayForArrays(arr2));

JSBIN for testing. MDN documentation on Array.prototype.every().

Edit: Keep in mind that there may be cases where you have a mix of data types, which would result in false. In such scenarios, using Array.prototype.some() can help.

Answer 5

Answer №3

Consider the following:

bar = {"coordinates":[30.0,10.0]}

typeof bar.coordinates[0]
"number"

foo = {"coordinates":
  [
    [[100.0,0.0],[101.0,0.0],[101.0,1.0],[100.0,1.0],[100.0,0.0]],
    [[100.2,0.2],[100.8,0.2],[100.8,0.8],[100.2,0.8],[100.2,0.2]]
  ]}

typeof foo.coordinates[0]
"object"

Then you could proceed with:

foo = (parse your JSON data here)
if (typeof foo.coordinates[0] == "object") {
   // processing polyline
}
else {
   // handling point
}

Answer 6

Consider the following:

bar = {"coordinates":[30.0,10.0]}

typeof bar.coordinates[0]
"number"

foo = {"coordinates":
  [
    [[100.0,0.0],[101.0,0.0],[101.0,1.0],[100.0,1.0],[100.0,0.0]],
    [[100.2,0.2],[100.8,0.2],[100.8,0.8],[100.2,0.8],[100.2,0.2]]
  ]}

typeof foo.coordinates[0]
"object"

Then you could proceed with:

foo = (parse your JSON data here)
if (typeof foo.coordinates[0] == "object") {
   // processing polyline
}
else {
   // handling point
}

Answer 7

Answer №4

This code snippet examines whether an array is a nested array:

let numbers = [10, 20, 30];
let nestedNumbers = [
  [1, 2, 3]
];

function checkArray(obj) {
  // In ES5 you could use obj.isArray
  return toString.call(obj) === "[object Array]";
}

function checkNestedArray(arr) {
  // Is it really an array?
  // If not, then it can't be a nested array
  if (!checkArray(arr)) {
    return false;
  }

  // Is the first element also an array?
  if (checkArray(arr[0])) {
    return true;
  }

  // Nope, not a nested array in this case
  return false;
}

console.log(checkNestedArray(numbers));
console.log(checkNestedArray(nestedNumbers));
console.log(checkNestedArray(null));

Answer 8

This code snippet examines whether an array is a nested array:

let numbers = [10, 20, 30];
let nestedNumbers = [
  [1, 2, 3]
];

function checkArray(obj) {
  // In ES5 you could use obj.isArray
  return toString.call(obj) === "[object Array]";
}

function checkNestedArray(arr) {
  // Is it really an array?
  // If not, then it can't be a nested array
  if (!checkArray(arr)) {
    return false;
  }

  // Is the first element also an array?
  if (checkArray(arr[0])) {
    return true;
  }

  // Nope, not a nested array in this case
  return false;
}

console.log(checkNestedArray(numbers));
console.log(checkNestedArray(nestedNumbers));
console.log(checkNestedArray(null));

Answer 9

Answer №5

Is there a simple way to determine whether the item being processed is an array?

Array.isArray(coordinates[0]); can be used to check if the first element in the coordinates array is actually an array (assuming that coordinates points to the value of the coordinates property).

You could also verify if the first element is a number instead.

function arePointCoords(coords) {
    return Array.isArray(coords) && typeof coords[0] === 'number';
}


arePointCoords([30.0,10.0]); //true
arePointCoords([
    [[100.0,0.0],[101.0,0.0],[101.0,1.0],[100.0,1.0],[100.0,0.0]],
    [[100.2,0.2],[100.8,0.2],[100.8,0.8],[100.2,0.8],[100.2,0.2]]
]); //false

It's worth mentioning that using domain-specific names rather than technical terms like arePointCoords(coords) instead of !isArrayOfArrays(coords) can improve code readability. Nonetheless, arePointCoords may internally rely on a more general function like isArrayOfArrays.

Answer 10

Is there a simple way to determine whether the item being processed is an array?

Array.isArray(coordinates[0]); can be used to check if the first element in the coordinates array is actually an array (assuming that coordinates points to the value of the coordinates property).

You could also verify if the first element is a number instead.

function arePointCoords(coords) {
    return Array.isArray(coords) && typeof coords[0] === 'number';
}


arePointCoords([30.0,10.0]); //true
arePointCoords([
    [[100.0,0.0],[101.0,0.0],[101.0,1.0],[100.0,1.0],[100.0,0.0]],
    [[100.2,0.2],[100.8,0.2],[100.8,0.8],[100.2,0.8],[100.2,0.2]]
]); //false

It's worth mentioning that using domain-specific names rather than technical terms like arePointCoords(coords) instead of !isArrayOfArrays(coords) can improve code readability. Nonetheless, arePointCoords may internally rely on a more general function like isArrayOfArrays.

Identification of a Collection of Arrays

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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