30. 使用LotusScript排序
排序是计算机编程中最常见的任务之一,排序算法也是最基本和常用的算法。存在许多种排序算法,它们的效率和复杂性各不相同。在LotusNotes中,公式语言里有@Sort函数,对List排序。LotusScript里没有类似的可以用作容器的数据结构,也就没有提供针对它们的排序功能。另外,使用LotusScript开发时,主要的数据对象是NotesDocument,而它们的排序都已经在视图里完成了,所以需
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排序是计算机编程中最常见的任务之一,排序算法也是最基本和常用的算法。存在许多种排序算法,它们的效率和复杂性各不相同。在LotusNotes中,公式语言里有@Sort函数,对List排序。LotusScript里没有类似的可以用作容器的数据结构,也就没有提供针对它们的排序功能。另外,使用LotusScript开发时,主要的数据对象是NotesDocument,而它们的排序都已经在视图里完成了,所以需要排序的情况并不多。但是有时候,我们也会遇到排序的需求,比如针对列表字段里的多值或是没有存在于文档中的数据。这时就需要我们在LotusScript里实现排序算法。这并不是特别困难的事,不过如果你想省事(像我一样),也可以使用现成的代码,比如下面的这几个用于排序的函数就来自于LotusNotes自带的模版数据库:
Public Function QuickSort(sArray As Variant) As Variant
Dim sA() As String
Dim j As Long
Dim bottom As Long
Dim top As Long
Dim vA As Variant
bottom = LBound ( sArray )
top = UBound ( sArray )
ReDim sA( bottom To top ) As String
For j = bottom To top
sA ( j ) = sArray ( j )
Next
' DoQS does a QuickSort if the Sublist is longer than 10 elements
' Thus, when DoQS finishes, all elements are within 10 spots of their correct location.
' For lists that are close to being in order, an Insertion Sort is much faster than a QuickSort, so we
' run through the whole thing once doing an Insertion Sort to finish tidying up the order.
Call DoQS( sA, bottom, top )
Call DoInsertSort ( sA, bottom, top )
ReDim vA(bottom To top) As Variant
For j = bottom To top
vA ( j ) = sA ( j )
Next
QuickSort = vA
End Function
Sub DoInsertSort ( sA() As String, ByVal bottom As Long, ByVal top As Long )
Dim i As Long
Dim x As Long
Dim v As String
Dim Found As Integer
For i = bottom+1 To top
x = i
v = sA (i )
Do While (sA(x-1) > v)
sA ( x ) = sA ( x-1 )
x = x - 1
If x=0 Then
Exit Do
End If
Loop
sA (x) = v
Next
End Sub
Sub DoQS( sA() As String, bottom As Long, top As Long )
' Called by QuickSort
Dim length As Long
Dim i As Long
Dim j As Long
Dim Pivot As Long
Dim PivotValue As String
Dim t As String
Dim LastSmall As Long
length = top - bottom + 1
' Only do the QuickSort if the sublist is at least 10 items long
If length > 10 Then
' Pivot is chosen approx. halfway through sublist.
' This gives us best speed if list is almost sorted already, and is no worse than any
' other choice if the list is in random order.
Pivot = bottom + (length \ 2)
' Move PivotValue out of the way
PivotValue = sA( Pivot )
sA ( Pivot ) = sA ( bottom )
sA ( bottom ) = PivotValue
' LastSmall is the location of the last value smaller than PivotValue
LastSmall = bottom
For i = bottom + 1 To top
If sA ( i ) < PivotValue Then
LastSmall = LastSmall + 1
t = sA ( i )
sA ( i ) = sA ( LastSmall )
sA ( LastSmall ) = t
End If
Next
' Move the PivotValue back
t = sA ( LastSmall )
sA ( LastSmall ) = sA ( bottom )
sA ( bottom ) = t
Pivot = LastSmall
' Now sort each side
Call DoQS ( sA, bottom, Pivot - 1 )
Call DoQS ( sA, Pivot + 1, top )
End If
End Sub
只需要调用QuickSort函数,它会对参数中的数组排序然后返回。它根据数组的大小采用快速排序和插入排序两种不同的算法。
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