This is a beginners video developed to give new users to MarcEdit's regular expression syntax a primer and examples on how to use the language. It provides information on strategies, resources, and hopefully, some useful hints to help get people started. These slides accompanied a youtube video which is available at: https://youtu.be/7YXvS4xBEfw

1. Getting Started with
Regular Expressions
in MarcEdit
TERRY REESE
HEAD OF DIGITAL INITIATIVES, THE OHIO STATE
UNIVERSITY

2. Topics
MarcEdit Regular Expression Support Information
Understanding .NET Regular Expressions
◦ Major components of the language
◦ Understanding grouping mechanisms and references
How Does MarcEdit implement expressions
Getting Regular Expression Help

3. MarcEdit Regular Expression
Support
Functions that presently support regular expressions
◦ Delete Field
◦ Edit Field
◦ Copy Field
◦ Swap Field
◦ Build New Field
◦ Extract/Delete Records
◦ Validation Processing
◦ Linked Data tooling
◦ More…

4. MarcEdit Regular Expression
Support
When processing regular expressions with MarcEdit, MarcEdit makes
entire fields or subfields available for processing
◦ i.e., when processing a delete field function – all data from =[field number]
are part of the field that can be queried.
MarcEdit’s regular expression by default deals with one field at a time
(i.e., regular expressions do not allow you to find data across fields by
default)
MarcEdit’s Regular Expression Support is defined by Microsoft .NET’s
Regular Expression object
◦ This object uses a syntax that looks Perl-like, but has some differences.

5. Microsoft’s Regular Expression
language
Concepts:
◦ Character escapes
◦ Anchors
◦ Character classes
◦ Grouping
◦ Qualifiers
◦ Substitutions
MSDN Documentation: https://msdn.microsoft.com/en-
us/library/az24scfc(v=vs.110).aspx
PDF Quick Reference:
http://download.microsoft.com/download/D/2/4/D240EBF6-A9BA-4E4F-
A63F-AEB6DA0B921C/Regular%20expressions%20quick%20reference.pdf

6. How we use Regular
Expressions in MarcEdit
Your most important parts of the regular expression language are:
1. Character escapes: drn$x##
2. Character Classes [] & [^]
3. Grouping Elements ()
4. Anchors: ^$
5. Quantifiers: *?+{#}
6. Substitutions: $#

7. How Expressions Manifest in
MarcEdit
Part of understanding regular expressions in
MarcEdit, is understanding what data is exposed to
the Regular expression engine.
Each of MarcEdit’s global edit functions see different
levels of data
This is important to understand when:
 Creating processing strategies
 Knowing which global editing function to choose

8. Replace Function

9. Replace Function
Provides:
 Access to all field data
 Can be processed across fields
(lines)
 Can do preconditional
sorting/evaluation before
evaluating for replacement (can
search for data in one field, and
then perform and action on
another if true)
 Provides most access to record
data for evaluation

10. Add/Delete Function

11. Add/Delete Function
Provides:
 Access to all field data from the
equal sign to end of line
 No option to evaluate across fields
 Only available when deleting data

12. Edit Field Data

13. Edit Field Data Function
Provides:
 Access all data after the indicators
(no indicator or field data access)
 Can be used to break up fields into
new fields and do recursive
searching

14. Edit Subfield Data

15. Edit Subfield Data
Provides:
 Only provides access to the defined
subfield or control data positions

16. Regular Expression Basics
I like to think of regular expressions the same way as I think of
diagraming a sentence.
http://www.english-grammar-
revolution.com/images/puzzler_words_october_2012.jpg

17. Regular Expression Basics
I am trying to look at the data I want to replace and break it into its
component parts. For example if I wanted to add a period to the 500 if
it is missing
Source Fields:
=500 $aPrime meridians: Greenwich and Washington
=500 $aPrime meridians: Greenwich and Washington?
Structure:
Expression: (=500.*[^W])$

18. Examples
Looking at example.txt using the replace function:
◦ Add a period to the 500 if it is missing
◦ Add a $h of cartographic resources between the $a and $c .
◦ Split the 856 into two fields, breaking on the $u.

19. Examples 1
◦ Add a period to the 500 if it is missing
◦ Find What: (=500.*[^W])$
◦ Replace With: $1.
Explanation:
◦ (=500.*[^W])$
◦ Searches for the 500, then matches all data in the line, until you get to the final character. It
then evaluates the final character to see if it’s a not a word character

20. Example 2
◦ Add a $h of cartographic resources between the $a and $c .
Find What: (=245.{4})($a.*)(/.*)
◦ (=245.{4})
◦ Match the 245 field with any value in the next 4 characters being valid.
◦ ($a.*)
◦ Select everything within the subfield a
◦ (/$c.*)
◦ Select the / value and the subfield c (and other data)
Replace With: $1$2$$h[cartographic resource] $3

21. Example 3
Split the 856 into two fields, breaking on the $u.
◦ Find What: (=856.{4})($u.*[^$])($u.*)
◦ (=856.{4})
◦ Matches the 856 field
◦ ($u.*[^$])
◦ Match $u, but stop at the end of the subfield
◦ ($u.*)
◦ Match reminder of field
◦ Replace With: $1$2n=856 41$3

22. Lcase/ucase
MarcEdit’s regular expression engine includes to extension functions for
dealing with case switching of characters.
◦ lcase & ucase
◦ Usage: (=450.{4})($a.)(.*)
◦ $1$2lcase($3)
◦ Example: Find the 500 with all upper case characters and convert the case of
all values but the first letter in the sentence to lower case.

23. Multi-Field Replacements
By default, MarcEdit handles one field at a time when doing regular
expressions.
◦ However, when you need to do evaluations against multiple fields, you can
by adding /m to the end of your replacement in the Replace Function in the
MarcEditor
◦ This is a special function added to the MarcEdit regular expression engine

24. Delete Field Function
The delete field function exposes all the data in the field to be acted
upon as a regular expression.
◦ i.e. =856 .*
◦ So the first value in the Delete Field evaluation is an =, not the subfield data
◦ The reason to do this is to allow for explicit evaluations of indicators.

25. Getting Regular Expression
Help
The MarcEdit Listserv has a number of regular expression experts that
provide a lot of help to users looking for it
http://metis3.gmu.edu/cgi-bin/wa?A0=MARCEDIT-L

26. Questions