Filtering Arrays of Person Objects

Oct 13, 2025 by wbrum.org 51 views

In the world of programming, challenges are an essential part of learning and growth. They help developers to improve their problem-solving skills, think critically, and develop a deeper understanding of programming concepts. In this article, we will explore some additional challenges that can help you improve your programming skills.

Filtering Arrays of Person Objects

Program to Filter an Array of Person Objects by ID

Filtering an array of person objects by ID is a common task in programming. It involves creating a function that takes an array of person objects and an ID as input, and returns a new array containing only the person objects with the specified ID.

Here is an example of how you can implement this function in JavaScript:

function filterById(persons, id) {
    return persons.filter(person => person.id === id);
}

This function uses the filter() method to create a new array containing only the person objects with the specified ID. The filter() method takes a callback function as an argument, which is called for each element in the array. If the callback function returns true, the element is included in the new array.

Program to Filter an Array of Person Objects where firstName is "John"

Filtering an array of person objects where the first name is "John" is similar to filtering by ID. However, instead of using the id property, we use the firstName property.

Here is an example of how you can implement this function in JavaScript:

function filterByFirstName(persons, firstName) {
    return persons.filter(person => person.firstName === firstName);
}

This function uses the filter() method to create a new array containing only the person objects with the specified first name.

Program to Filter an Array of Person Objects where lastName is "Doe"

Filtering an array of person objects where the last name is "Doe" is similar to filtering by first name. However, instead of using the firstName property, we use the lastName property.

Here is an example of how you can implement this function in JavaScript:

function filterByLastName(persons, lastName) {
    return persons.filter(person => person.lastName === lastName);
}

This function uses the filter() method to create a new array containing only the person objects with the specified last name.

Program to Filter an Array of Person Objects where gender is "Male"

Filtering an array of person objects where the gender is "Male" is similar to filtering by last name. However, instead of using the lastName property, we use the gender property.

Here is an example of how you can implement this function in JavaScript:

function filterByGender(persons, gender) {
    return persons.filter(person => person.gender === gender);
}

This function uses the filter() method to create a new array containing only the person objects with the specified gender.

Program to Filter an Array of Person Objects where age is 25

Filtering an array of person objects where the age is 25 is similar to filtering by gender. However, instead of using the gender property, we use the age property.

Here is an example of how you can implement this function in JavaScript:

function filterByAge(persons, age) {
    return persons.filter(person => person.age === age);
}

This function uses the filter() method to create a new array containing only the person objects with the specified age.

Listing Out All Keys of a Person Object

Sometimes, you may need to list out all the keys of a person object. This can be useful when you need to iterate over the properties of the object.

Here is an example of how you can list out all the keys of a person object in JavaScript:

function listKeys(person) {
    return Object.keys(person);
}

This function uses the Object.keys() method to return an array containing all the keys of the person object.

Adding Two Matrices Using Multi-Dimensional Arrays

Adding two matrices using multi-dimensional arrays is a common task in programming. It involves creating a function that takes two matrices as input, and returns a new matrix containing the sum of the two input matrices.

Here is an example of how you can implement this function in JavaScript:

function addMatrices(matrix1, matrix2) {
    const result = [];
    for (let i = 0; i < matrix1.length; i++) {
        result[i] = [];
        for (let j = 0; j < matrix1[i].length; j++) {
            result[i][j] = matrix1[i][j] + matrix2[i][j];
        }
    }
    return result;
}

This function uses two nested loops to iterate over the elements of the two input matrices. It then adds the corresponding elements of the two matrices and stores the result in a new matrix.

Multiplying Two Matrices Using Multi-Dimensional Arrays

Multiplying two matrices using multi-dimensional arrays is similar to adding two matrices. However, instead of adding the corresponding elements of the two matrices, we multiply them.

Here is an example of how you can implement this function in JavaScript:

function multiplyMatrices(matrix1, matrix2) {
    const result = [];
    for (let i = 0; i < matrix1.length; i++) {
        result[i] = [];
        for (let j = 0; j < matrix2[0].length; j++) {
            let sum = 0;
            for (let k = 0; k < matrix1[0].length; k++) {
                sum += matrix1[i][k] * matrix2[k][j];
            }
            result[i][j] = sum;
        }
    }
    return result;
}

This function uses three nested loops to iterate over the elements of the two input matrices. It then multiplies the corresponding elements of the two matrices and stores the result in a new matrix.

Finding the Transpose of a Matrix

Finding the transpose of a matrix is a common task in programming. It involves creating a function that takes a matrix as input, and returns a new matrix containing the transpose of the input matrix.

Here is an example of how you can implement this function in JavaScript:

function transposeMatrix(matrix) {
    const result = [];
    for (let i = 0; i < matrix[0].length; i++) {
        result[i] = [];
        for (let j = 0; j < matrix.length; j++) {
            result[i][j] = matrix[j][i];
        }
    }
    return result;
}

This function uses two nested loops to iterate over the elements of the input matrix. It then swaps the rows and columns of the input matrix and stores the result in a new matrix.

Finding the Frequency of Characters in a String

Finding the frequency of characters in a string is a common task in programming. It involves creating a function that takes a string as input, and returns an object containing the frequency of each character in the string.

Here is an example of how you can implement this function in JavaScript:

function frequencyOfCharacters(string) {
    const frequency = {};
    for (let i = 0; i < string.length; i++) {
        const char = string[i];
        if (frequency[char]) {
            frequency[char]++;
        } else {
            frequency[char] = 1;
        }
    }
    return frequency;
}

This function uses a loop to iterate over the characters of the input string. It then increments the frequency of each character in the frequency object.

Counting the Number of Vowels, Consonants in a String

Counting the number of vowels and consonants in a string is a common task in programming. It involves creating a function that takes a string as input, and returns an object containing the number of vowels and consonants in the string.

Here is an example of how you can implement this function in JavaScript:

function countVowelsConsonants(string) {
    const vowels = 'aeiou';
    const frequency = { vowels: 0, consonants: 0 };
    for (let i = 0; i < string.length; i++) {
        const char = string[i].toLowerCase();
        if (vowels.includes(char)) {
            frequency.vowels++;
        } else if (char.match(/[a-z]/)) {
            frequency.consonants++;
        }
    }
    return frequency;
}

This function uses a loop to iterate over the characters of the input string. It then increments the frequency of vowels and consonants in the frequency object.

Removing All Characters in a String Except Alphabet

Removing all characters in a string except alphabet is a common task in programming. It involves creating a function that takes a string as input, and returns a new string containing only the alphabet characters.

Here is an example of how you can implement this function in JavaScript:

function removeNonAlphabet(string) {
    return string.replace(/[^a-z]/gi, '');
}

This function uses the replace() method to remove all non-alphabet characters from the input string.

Finding the Length of a String

Finding the length of a string is a common task in programming. It involves creating a function that takes a string as input, and returns the length of the string.

Here is an example of how you can implement this function in JavaScript:

function lengthOfString(string) {
    return string.length;
}

This function uses the length property to return the length of the input string.

Concatenating Two Strings

In this article, we will answer some frequently asked questions related to the additional programming challenges we discussed earlier.

Q: How do I filter an array of person objects by ID?

A: You can use the filter() method to create a new array containing only the person objects with the specified ID. Here is an example of how you can implement this function in JavaScript:

function filterById(persons, id) {
    return persons.filter(person => person.id === id);
}

Q: How do I filter an array of person objects where the first name is "John"?

A: You can use the filter() method to create a new array containing only the person objects with the specified first name. Here is an example of how you can implement this function in JavaScript:

function filterByFirstName(persons, firstName) {
    return persons.filter(person => person.firstName === firstName);
}

Q: How do I filter an array of person objects where the last name is "Doe"?

A: You can use the filter() method to create a new array containing only the person objects with the specified last name. Here is an example of how you can implement this function in JavaScript:

function filterByLastName(persons, lastName) {
    return persons.filter(person => person.lastName === lastName);
}

Q: How do I filter an array of person objects where the gender is "Male"?

A: You can use the filter() method to create a new array containing only the person objects with the specified gender. Here is an example of how you can implement this function in JavaScript:

function filterByGender(persons, gender) {
    return persons.filter(person => person.gender === gender);
}

Q: How do I filter an array of person objects where the age is 25?

A: You can use the filter() method to create a new array containing only the person objects with the specified age. Here is an example of how you can implement this function in JavaScript:

function filterByAge(persons, age) {
    return persons.filter(person => person.age === age);
}

Q: How do I list out all the keys of a person object?

A: You can use the Object.keys() method to return an array containing all the keys of the person object. Here is an example of how you can implement this function in JavaScript:

function listKeys(person) {
    return Object.keys(person);
}

Q: How do I add two matrices using multi-dimensional arrays?

A: You can use two nested loops to iterate over the elements of the two input matrices. You then add the corresponding elements of the two matrices and store the result in a new matrix. Here is an example of how you can implement this function in JavaScript:

function addMatrices(matrix1, matrix2) {
    const result = [];
    for (let i = 0; i < matrix1.length; i++) {
        result[i] = [];
        for (let j = 0; j < matrix1[i].length; j++) {
            result[i][j] = matrix1[i][j] + matrix2[i][j];
        }
    }
    return result;
}

Q: How do I multiply two matrices using multi-dimensional arrays?

A: You can use three nested loops to iterate over the elements of the two input matrices. You then multiply the corresponding elements of the two matrices and store the result in a new matrix. Here is an example of how you can implement this function in JavaScript:

function multiplyMatrices(matrix1, matrix2) {
    const result = [];
    for (let i = 0; i < matrix1.length; i++) {
        result[i] = [];
        for (let j = 0; j < matrix2[0].length; j++) {
            let sum = 0;
            for (let k = 0; k < matrix1[0].length; k++) {
                sum += matrix1[i][k] * matrix2[k][j];
            }
            result[i][j] = sum;
        }
    }
    return result;
}

Q: How do I find the transpose of a matrix?

A: You can use two nested loops to iterate over the elements of the input matrix. You then swap the rows and columns of the input matrix and store the result in a new matrix. Here is an example of how you can implement this function in JavaScript:

function transposeMatrix(matrix) {
    const result = [];
    for (let i = 0; i < matrix[0].length; i++) {
        result[i] = [];
        for (let j = 0; j < matrix.length; j++) {
            result[i][j] = matrix[j][i];
        }
    }
    return result;
}

Q: How do I find the frequency of characters in a string?

A: You can use a loop to iterate over the characters of the input string. You then increment the frequency of each character in the frequency object. Here is an example of how you can implement this function in JavaScript:

function frequencyOfCharacters(string) {
    const frequency = {};
    for (let i = 0; i < string.length; i++) {
        const char = string[i];
        if (frequency[char]) {
            frequency[char]++;
        } else {
            frequency[char] = 1;
        }
    }
    return frequency;
}

Q: How do I count the number of vowels and consonants in a string?

A: You can use a loop to iterate over the characters of the input string. You then increment the frequency of vowels and consonants in the frequency object. Here is an example of how you can implement this function in JavaScript:

function countVowelsConsonants(string) {
    const vowels = 'aeiou';
    const frequency = { vowels: 0, consonants: 0 };
    for (let i = 0; i < string.length; i++) {
        const char = string[i].toLowerCase();
        if (vowels.includes(char)) {
            frequency.vowels++;
        } else if (char.match(/[a-z]/)) {
            frequency.consonants++;
        }
    }
    return frequency;
}

Q: How do I remove all characters in a string except alphabet?

A: You can use the replace() method to remove all non-alphabet characters from the input string. Here is an example of how you can implement this function in JavaScript:

function removeNonAlphabet(string) {
    return string.replace(/[^a-z]/gi, '');
}

Q: How do I find the length of a string?

A: You can use the length property to return the length of the input string. Here is an example of how you can implement this function in JavaScript:

function lengthOfString(string) {
    return string.length;
}

Q: How do I concatenate two strings?

A: You can use the + operator to concatenate two strings. Here is an example of how you can implement this function in JavaScript:

function concatenateStrings(string1, string2) {
    return string1 + string2;
}

Q: How do I sort string elements in lexicographical order?

A: You can use the sort() method to sort the string elements in lexicographical order. Here is an example of how you can implement this function in JavaScript:

function sortStringElements(strings) {
    return strings.sort();
}