# groupby

Published articles for groupby.

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## Collections: Maps

DevFeed: [Collections: Maps](<https://devfeed.tech/articles/collections-maps-25060.md>)

Original publisher: [Read original article](<https://typealias.com/start/kotlin-maps/>)

Author: author@typealias.com (Dave Leeds)

Published: 2022-05-04T00:00:00Z

Content type: tutorial

Language: en

Sources: [Dave Leeds on Kotlin - typealias.com](<https://devfeed.tech/sources/dave-leeds-on-kotlin-typealias-com.md>)

Topics: [Kotlin](<https://devfeed.tech/topics/kotlin.md>), [data](<https://devfeed.tech/topics/data.md>)

Tags: [associate](<https://devfeed.tech/tags/associate.md>), [association](<https://devfeed.tech/tags/association.md>), [build](<https://devfeed.tech/tags/build.md>), [collections](<https://devfeed.tech/tags/collections.md>), [groupby](<https://devfeed.tech/tags/groupby.md>), [how-to](<https://devfeed.tech/tags/how-to.md>), [introduction](<https://devfeed.tech/tags/introduction.md>), [kotlin](<https://devfeed.tech/tags/kotlin.md>), [learn-to-program](<https://devfeed.tech/tags/learn-to-program.md>), [map](<https://devfeed.tech/tags/map.md>), [maps](<https://devfeed.tech/tags/maps.md>), [pair](<https://devfeed.tech/tags/pair.md>), [programming](<https://devfeed.tech/tags/programming.md>)

### AI overview

A tutorial chapter introduces maps as a Kotlin collection for storing associations between values. It explains the concept using a hardware-and-tools example and begins showing how to create associations with a class constructor.

### Source excerpt

In the last chapter, we saw how collections, such as lists and sets, can be used to do things that couldn't be done easily with separate, individual variables. In this chapter, we're going to look at another kind of collection--a map, which can hold many associations between values. Let's check it out! The Right Tool for the Job "You gotta use the right tool for the job." That's what Mr. Patchwell taught his young son, Jack, who was just starting to learn how to become a handyman like his old man.

## Effective Kotlin Item 56: Consider using groupingBy instead of groupBy

DevFeed: [Effective Kotlin Item 56: Consider using groupingBy instead of groupBy](<https://devfeed.tech/articles/effective-kotlin-item-56-consider-using-groupingby-instead-of-groupby-39280.md>)

Original publisher: [Read original article](<https://kt.academy/article/ek-grouping>)

Published: 2021-10-11T00:00:00Z

Content type: tutorial

Language: en

Sources: [Kt. Academy](<https://devfeed.tech/sources/kt-academy.md>)

Topics: [groupby](<https://devfeed.tech/topics/groupby.md>), [Kotlin](<https://devfeed.tech/topics/kotlin.md>), [Optimization](<https://devfeed.tech/topics/optimization.md>), [performance-optimization](<https://devfeed.tech/topics/performance-optimization.md>), [Collections](<https://devfeed.tech/topics/collections.md>)

Tags: [code](<https://devfeed.tech/tags/code.md>), [collections](<https://devfeed.tech/tags/collections.md>), [groupby](<https://devfeed.tech/tags/groupby.md>), [kotlin](<https://devfeed.tech/tags/kotlin.md>), [optimization](<https://devfeed.tech/tags/optimization.md>), [performance](<https://devfeed.tech/tags/performance.md>), [standard-library](<https://devfeed.tech/tags/standard-library.md>), [workshop-learning-programming](<https://devfeed.tech/tags/workshop-learning-programming.md>)

### AI overview

This tutorial explains how Kotlin's groupBy and groupingBy functions organize elements from an iterable by key. It describes groupBy as the simpler option that creates collections for each key, while groupingBy can reduce work and memory use in performance-critical code by processing groups through operations such as counting and aggregation.

### Source excerpt

What Grouping is, and how groupingBy instead of groupBy can be a performance optimization.