Grouping Array Elements | Data Processing | JavaScript Techniques

Introduction

In this lab, we will be exploring how to group array elements based on their position in the original arrays. We will be using the zip() function which takes in multiple arrays and returns a new array containing sub-arrays of elements from each input array, grouped by their position. This is a useful technique in data processing and analysis, and can be used to combine data from multiple sources into a single data structure for further analysis.

Skills Graph

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Group Array Elements

To group elements of arrays based on their position in the original arrays, use the zip function provided below.

Open the Terminal/SSH and type node to start practicing coding.
The zip function uses Math.max() and Function.prototype.apply() to get the longest array in the arguments.
It creates an array with that length as the return value and uses Array.from() with a mapping function to create an array of grouped elements.
If the lengths of the argument arrays vary, undefined is used where no value could be found.

const zip = (...arrays) => {
  const maxLength = Math.max(...arrays.map((x) => x.length));
  return Array.from({ length: maxLength }).map((_, i) => {
    return Array.from({ length: arrays.length }, (_, k) => arrays[k][i]);
  });
};

Example usage:

zip(["a", "b"], [1, 2], [true, false]); // [['a', 1, true], ['b', 2, false]]
zip(["a"], [1, 2], [true, false]); // [['a', 1, true], [undefined, 2, false]]

Summary

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Group Data from Multiple Arrays

Introduction

Skills Graph

Group Array Elements

Summary

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