Scala中的序列

2024-04-18 13:39:04 334

Scala|顺序

Scala中的序列是一个集合，用于按确定的顺序存储元素。它是索引数据存储区，它允许使用基于0索引的元素的索引来顺序访问其元素。

它是可迭代类的可迭代集合，从中可获取其属性。该返回的有序列表或向量。=在插入顺序被保持。

在Scala中创建序列

首先了解如何在Scala中创建序列。以下语法用于在Scala中创建列表，

语法：

1)  Creating an empty sequence,
    var emptySeq: Seq[data_type] = Seq();
2)  Creating an Sequence with defining the data type,
    var mySeq: Seq[data_type] = Seq(element1, element2, ...)
3)  Creating an Sequence without defining the data type,
    var mySeq = Seq(element1, element2, ...)

演示如何在Scala中创建序列的程序

// Program to show how to create a list is Scala

object MyObject {
    def main(args: Array[String]) {
        // Creating an empty Sequence in Scala 
        println("Creating an Empty Sequence!")
        var empSeq: Seq[Int] = Seq();
        println("Empty Sequence : " + empSeq)
        
        // Creating a Sequence by defining its data type    
        println("\nCreating a Sequence by defining its data type ")
        var mySeq: Seq[String] = Seq("Scala", "JavaScript", "Python");
        println("Sequence of type 'String': " + mySeq)
        
        // Creating a Sequence without defining its data type    
        println("\nCreating a Sequence without defining its data type ")
        var mySeq2 = Seq(4 ,1 , 6, 7, 2)
        println("Sequence without defining its data type: " + mySeq2)
    }
}

输出：

Creating an Empty Sequence!
Empty Sequence : List()Creating a Sequence by defining its data type 
Sequence of type 'String': List(Scala, JavaScript, Python)Creating a Sequence without defining its data type 
Sequence without defining its data type: List(4, 1, 6, 7, 2)

Scala中的序列类型

在scala中使用了特征序列的两种类型或子特征。

他们是：

索引序列：索引序列或IndexedSeq返回一个向量，该向量允许对元素的随机和快速访问。

线性序列：线性序列或LinerSeq返回一个List，该List允许快速访问仅第一个和最后一个元素，其余按顺序访问。

程序来说明不同类型的序列

// Program to illustrate different types of Sequence

import scala.collection._

    object MyObject {
        def main(args: Array[String]) {
        
        // Creating a Indexed Sequence in Scala 
        val IndSeq = IndexedSeq(3, 6, 9, 12, 15, 18)
        println("Indexed Sequence: " + IndSeq)
        
        // Creating a Linear Sequence in Scala 
        val LinSeq = LinearSeq(2, 4, 6, 8, 10, 12, 14)
        println("Linear Sequence: " + LinSeq)
    }
}

输出：

Indexed Sequence: Vector(3, 6, 9, 12, 15, 18)
Linear Sequence: List(2, 4, 6, 8, 10, 12, 14)

常用的序列类型是线性序列。如果仅使用seq关键字初始化序列，则会创建LinerSeq。

Scala序列的操作

Scala中的序列具有许多预定义的功能和要在其上执行的操作。尽管元素不能更改，因为它是不可变的。但是可以执行提取给定索引的元素，查找长度等操作。

程序以给定序列索引访问元素

// Program to access element at a 
// given index of the sequence

object MyObject {
    def main(args: Array[String]) {
        // Creating a Sequence in Scala 
        val mySeq = Seq(3, 6, 9, 12, 15, 18)
        println("Sequence: " + mySeq)
        
        // Access elements at a specific index
        println("Element at index 0: " + mySeq(0))
        println("Element at index 4: "  + mySeq(4))
    }
}

输出：

Sequence: List(3, 6, 9, 12, 15, 18)
Element at index 0: 3
Element at index 4: 15

在Sequence上预定义的常用方法

length：定义序列长度的字段。length：定义序列长度的字段。
语法：
Sequence_name.length

reverse：用于返回新顺序的函数，该顺序为逆序。
语法：
Sequence_name.reverse

isEmpty：用于检查序列是否为空的函数。
语法：
Sequence_name.isEmpty

该程序演示了一些常用的Sequence方法的工作

// Program to access element at a given index of the sequence

object MyObject {
    def main(args: Array[String]) {
        // Creating a Sequence in Scala 
        val mySeq = Seq(3, 6, 9, 12, 15, 18)
        println("Sequence: " + mySeq)
        
        // Checking if the sequence is empty or not
        if(mySeq.isEmpty)
        println("\nThe given Sequence is empty")
        else
        println("\nThe given Sequence is not empty")  
        
        // Finding the length of sequence 
        val len = mySeq.length
        println("\nThe length of the seqeunce is " + len)
        
        // Reversing the sequence
        val revSeq = mySeq.reverse
        println("\nThe reverse of the seqeunce is " + revSeq)
    }
}

输出：

Sequence: List(3, 6, 9, 12, 15, 18)

The given Sequence is not empty

The length of the seqeunce is 6

The reverse of the seqeunce is List(18, 15, 12, 9, 6, 3)

Scala为序列定义了更多方法，这些方法将在以后的文章中看到。

Scala中的序列

Scala|顺序

在Scala中创建序列

演示如何在Scala中创建序列的程序

Scala中的序列类型

程序来说明不同类型的序列

Scala序列的操作

程序以给定序列索引访问元素

在Sequence上预定义的常用方法

该程序演示了一些常用的Sequence方法的工作

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