8.32. Scala Mapping

发布时间 : 2023-11-20 23:00:02 UTC      

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mapping is an iterative key-value pair (key/value) structure.

All values can be obtained by key.

The keys in Map are unique.

Map also known as Hash tables.

Map has two types, mutable and immutable, the difference is that a mutable object can modify it, while an immutable object cannot.

Scala usage is immutable by default Map . If you need to use mutable sets, you need to explicitly introduce import scala.collection.mutable.Map Class

In Scala, you can use both mutable and immutable. Map immutable direct use Map , variable use mutable.Map . The following example demonstrates immutability Map application:

// An empty hash table with keys as strings and values as integers
var A:Map[Char,Int] = Map()

// Map Key Value Pair Demonstration
val colors = Map("red" -> "#FF0000", "azure" -> "#F0FFFF")

Define Map you need to define a type for the key-value pair. If you need to add key-value , you can use the + sign, as follows:

Principles, Technologies, and Methods of Geographic Information Systems  102

In recent years, Geographic Information Systems (GIS) have undergone rapid development in both theoretical and practical dimensions. GIS has been widely applied for modeling and decision-making support across various fields such as urban management, regional planning, and environmental remediation, establishing geographic information as a vital component of the information era. The introduction of the “Digital Earth” concept has further accelerated the advancement of GIS, which serves as its technical foundation. Concurrently, scholars have been dedicated to theoretical research in areas like spatial cognition, spatial data uncertainty, and the formalization of spatial relationships. This reflects the dual nature of GIS as both an applied technology and an academic discipline, with the two aspects forming a mutually reinforcing cycle of progress.