[Excel] Convert a string into an alphabet (A) & numeric (N) map

[Excel] ANNA_MAP

Function ANNA_MAP(anna_text As String) As String
    Dim map As String
    Dim RegExp As Object
    Set RegExp = CreateObject("VBScript.RegExp")
    Dim aPattern As String
    Dim nPattern As String
    Dim cPattern As String
    
    aPattern = "[a-zA-Z]"
    nPattern = "[0-9]"
    cPattern = "[^a-zA-Z0-9]"
  
    For I = 1 To Len(anna_text)
        RegExp.Pattern = aPattern
        If RegExp.Test(Mid(anna_text, I, 1)) Then
            map = map & "A"
        End If
        RegExp.Pattern = nPattern
        If RegExp.Test(Mid(anna_text, I, 1)) Then
            map = map & "N"
        End If
        RegExp.Pattern = cPattern
        If RegExp.Test(Mid(anna_text, I, 1)) Then
            map = map & Mid(anna_text, I, 1)
        End If
        
    Next

    ANNA_MAP = map
    
    Set RegExp = Nothing
    
End Function