如何使用正则表达式匹配不连续的字符串

Question

This question is probably simple for others, but I'm new to RegEx and to this forum, and haven't been able to find an answer anywhere.

I have emails coming into Microsoft Outlook that generally look like this:

---

Patient: SMITH, JANE

MRN: 12345678

EncounterID: 1234567890

EncounterDate: Apr 11 2017 12:00AM

Department: NEUROLOGY

Center: Headache

Location: Main Campus

Visit Type: NEW NEUR HEADACHE

Attending Phys: JONES, MARY

---

I want to have Outlook examine each email as it arrives, select those whose subject line indicates that they have relevant information, then extract the MRN, Last Name of patient, First Name of patient, and Encounter Date.

When a new email arrives, my module runs the following Sub:

Public Sub ProcessImatchKpEmails(item As Outlook.MailItem)
Dim LastName As String
Dim FirstName As String
Dim EncounterDate As String
Dim MRN As String
Dim Body As String

On Error Resume Next

'   Check to make sure it is an Outlook mail message.
    If TypeName(item) <> "MailItem" Then Exit Sub
    Body = item.Body

'   Exract data from the email
    If item.Subject =  _
        gImatchKpEmailSubjectNo Or item.Subject = _ 
        gImatchKpEmailSubjectYes Or _
        item.Subject=_gImatchKpEmailSubjectMaybe Then
           MRN = ExtractText(Body, RegPattern("MRN"))
           LastName = ExtractText(Body, RegPattern("LastName"))
           FirstName = ExtractText(Body, RegPattern("FirstName"))
           EncounterDate = ExtractText(Body, RegPattern("EncounterDate"))
    End If
End Sub

The RegPattern function looks like this:

Public Function RegPattern(Lookup As String) As String 'Creates a 
  regPattern for each type of lookup

On Error Resume Next

    Select Case Lookup
        Case "LastName"
            RegPattern = "Patient\s*[:]+\s*(\w*)\s*"
        Case "FirstName"
            RegPattern = "Patient\s*[:]+\s*(\w*)[,](\w*)\s*"
        Case "EncounterDate"
            RegPattern = "EncounterDate\s*[:]+\s*(\w*)\s*" 
        Case "MRN"
            RegPattern = "MRN\s*[:]+\s*(\d*)\s*"
    End Select

    Debug.Print Lookup, RegPattern

End Function

The ExtractText Function looks like this:

Public Function ExtractText(Str As String, RegPattern As String) As 
   String
Dim regEx As New RegExp
Dim numMatches As MatchCollection
Dim M As Match

On Error Resume Next

regEx.Pattern = RegPattern

Set numMatches = regEx.Execute(Str)
If numMatches.Count = 0 Then
    ExtractText = "missing"
Else
    Set M = numMatches(0)
    ExtractText = M.SubMatches(0)
End If

Debug.Print ExtractText
End Function

When I run this, the code picks up the new email, and it manages to pull the MRN (12345678) and Last Name of Patient (Smith) accurately.

However, it also pulls the First Name of Patient as (Smith). Similarly, it pulls the Encounter Date as (Apr), but loses the rest.

Can anybody tell me what the appropriate RegEx code would be to get the patient's first name, as well as the entire Encounter Date?

Thanks for your help.

Answer 1

"Patient\\s*[:]+\\s*(\\w*)[,](\\w*)\\s*"

The core problem is that you always extract the 0th submatch; but you have two sets of capturing parentheses. Changing the first set of parentheses into non-capturing ones should help:

"Patient\s*[:]+\s*(?:\w*)[,](\w*)\s*"

Or even having no parentheses for the first name, as there's no reason why you should need grouping there.

Also note that [:] is identical to : , and you probably want to capture at least one character for names, which is \\w+ instead of \\w* .