how to return a list of 10 objects selected randomly. The array should include at least 1 adjective, 1 adverb, 1 noun, and 1 verb

Question

[
  {
    "id": 1,
    "pos": "adverb"
  },
  {
    "id": 2,
    "pos": "verb"
  },
  {
    "id": 3,
    "pos": "noun"
  },
  {
    "id": 4,
    "pos": "verb"
  },
  {
    "id": 5,
    "pos": "noun"
  },
  {
    "id": 6,
    "pos": "verb"
  },
  {
    "id": 7,
    "pos": "adjective"
  },
  {
    "id": 8,
    "pos": "noun"
  },
  {
    "id": 9,
    "pos": "adjective"
  },
  {
    "id": 10,
    "pos": "noun"
  }
]

Return Random Array With 10 Items In JavaScript, The array should include at least 1 of each "pos"

want to return a random array that includes 10 items from the array above, which should have at least 1 of each pos.

I tried to do it but I'm getting random data and cannot control having at least 1 of each pos.

Answer 1

Make an array each for the parts of speech.

const allPos = p => bigArray.filter(word => word.pos === p);
const verbs = allPos("verb");
const nouns = //...

Borrow a shuffler function (like this)

shuffle(verbs);
shuffle(nouns);
//...

Build the result with a round-robin pop from each array...

let posGroups = [verbs, nouns, ...];
let posIndex = 0;
let count = 0
let result = [];

while (count++ < 10) {
  let word = posGroups[posIndex].pop();
  if (word) result.push(word);
  posIndex = posIndex < posGroups.length-1 ? posIndex+1 : 0;
}

Answer 2

Since you seem pretty new to this subject, here is a more lengthy way with comments to explain how to solve your problem. This is possible in a more concise way (see answer of danh), but I think that a step-by-step solution will be more readable for a beginner.

Note: This solution does not implement a shuffle algorithm. If you care about that, see answer of danh.

// Your array containing the mentioned objects.
const items = [
    {
        id: 1,
        word: 'slowly',
        pos: 'adverb',
    },
    {
        id: 2,
        word: 'ride',
        pos: 'verb',
    },
    {
        id: 3,
        word: 'bus',
        pos: 'noun',
    },
    {
        id: 4,
        word: 'commute',
        pos: 'verb',
    },
    {
        id: 5,
        word: 'emissions',
        pos: 'noun',
    },
    {
        id: 6,
        word: 'walk',
        pos: 'verb',
    },
    {
        id: 7,
        word: 'fast',
        pos: 'adjective',
    },
    {
        id: 8,
        word: 'car',
        pos: 'noun',
    },
    {
        id: 9,
        word: 'crowded',
        pos: 'adjective',
    },
    {
        id: 10,
        word: 'arrival',
        pos: 'noun',
    },
    {
        id: 11,
        word: 'emit',
        pos: 'verb',
    },
    {
        id: 12,
        word: 'independent',
        pos: 'adjective',
    },
    {
        id: 13,
        word: 'convenient',
        pos: 'adjective',
    },
    {
        id: 14,
        word: 'lane',
        pos: 'noun',
    },
    {
        id: 15,
        word: 'heavily',
        pos: 'adverb',
    },
];

// The function for selecting random elements from the array.
function getRandomItems(itemCount) {
    // The array we will use for our selected items.
    const selectedItems = [];

    // Get all unique values for property "pos".
    const distinctPos = [...new Set(items.map((item) => item.pos))];

    // Subtract the count of found distinct "pos" values from the item count.
    itemCount -= distinctPos.length;

    if (itemCount < 0) {
        // Implement proper error handling.
        throw "The count of items cannot be less than the amount of distinct pos!";
    }

    // Iterate through every found distinct "pos" value.
    for (i = 0; i < distinctPos.length; i++) {
        // Get all objects for the current distinct value of "pos".
        const itemsWithDistinctPos = items.filter(
            (item) => item.pos === distinctPos[i]
        );

        // Get a random item with the current "pos" value and add it to the result array.
        selectedItems.push(getRandomItemFromArray(itemsWithDistinctPos));
    }

    // Get the rest of the values without caring about the "pos" value.
    for (i = 0; i < itemCount; i++) {
        // Add a random object from the array to the result array.
        selectedItems.push(getRandomItemFromArray(items));
    }

    // Return the result array.
    return selectedItems;
}

function getRandomItemFromArray(array) {
    // Get a random element from the array.
    return array[Math.floor(Math.random() * array.length)];
}

// Now call the method like this.
const selectedItems = getRandomItems(10);