Page tree

Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.
Comment: Published by Scroll Versions from space DEV and version next

D toc

Unlike other types of data, text data has very few restrictions on the kinds of values that appear in a cell. In the application, this data is typically inferred as String data type. As a result, finding string values that mean the same thing can be a challenge, as minor differences in their content or structure can invalidate a match.

This section provides some methods for comparing strings.

  • Some target systems may impose limits on the lengths of imported values. For more information on managing the lengths of your strings, see Manage String Lengths.

Find Substrings

You can use the following functions to locate sub-strings that are part of a column's value. 

Function NameDescription
LEFT Function

D excerpt include
pageLEFT Function
nopaneltrue

RIGHT Function

D excerpt include
pageRIGHT Function
nopaneltrue

FIND Function

D excerpt include
pageFIND Function
nopaneltrue

RIGHTFIND Function

D excerpt include
pageRIGHT Function
nopaneltrue

SUBSTRING Function

D excerpt include
pageSUBSTRING Function
nopaneltrue

The following transformation checks the left five values of the lowercase version of the ProdId column to see if it matches xxxx-. If the value is detected, then the ProdName value is set to NO_NAME:

 

D trans
Typestep
p01NameColumns
p01ValueProdName
p02NameFormula
p02ValueIF(LEFT(LOWER(ProdId,5))=='xxxx-','NO_NAME' ,ProdName)
SearchTermEdit with formula

Compare String Ends by Pattern

You can use the STARTSWITH and ENDSWITH functions to determine if a string begins or ends with a specified pattern.

Tip

Tip: These functions are most useful for performing pattern-based checks on strings. For string literals, you can use the LEFT and RIGHT functions. See below.

The following transformation inserts the value error in the custCodeStatus column if the custCode value begins with six digits in a row:

D trans
Typestep
p01NameColumns
p01ValuecustCodeStatus
p02NameFormula
p02ValueIF(STARTSWITH(custCode,`{digit}{6}`), 'error',custCodeStatus)
SearchTermEdit with formula

See STARTSWITH Function.

See ENDSWITH Function.

Match Strings

Exact matching

You can use the EXACT function to compare if two strings are exact matches. String inputs can be literals, column references, or expressions that evaluate to strings. 

Info

NOTE: The EXACT function evaluates for exact matches. Whitespace or capitalization differences return false.

You can nest function expressions inside of the EXACT reference to eliminate common and perhaps not useful differences between strings. In the following transformation, a value of true is inserted into the matches column, if colA and colB are exact matches, after whitespace and case differences have been removed:

D trans
Typestep
p01NameFormula
p01ValueIF(EXACT(LOWER(REMOVEWHITESPACE(colA)))==EXACT(LOWER(REMOVEWHITESPACE(colB))),'true','false')
p02NameNew column name
p02Valuematches
SearchTermNew formula

Doublemetaphone matching

The platform also supports the doublemetaphone algorithm for fuzzy matching. This algorithm provides mechanism for proximity matching; the DOUBLEMETAPHONEEQUALS function supports an optional second parameter to define the strength of the algorithm.

This algorithm works by generating two separate encodings for each string: a primary encoding and a secondary encoding. You can experiment with these encodings using the DOUBLEMETAPHONE function. See DOUBLEMETAPHONE Function.

This algorithm can be applied to compare two strings, as in the following transformation.

D trans
Typestep
p01NameFormula
p01ValueDOUBLEMETAPHONEEQUALS(colA,colB,'strong')
p02NameNew column name
p02Valuematches
SearchTermNew formula

  • The first two parameters of the function are the string literals, column references, or functions returning strings to compare.
  • The third parameter is optional. It determines the level of matching required to return true. Options:

    Match thresholdDescription
    'strong'Both primary encodings must match.
    'normal'At least one primary encoding must match either of the other string's encodings
    'weak'A primary or secondary encoding from each can match.
  • For more information, see DOUBLEMETAPHONEEQUALS Function.

Compare Strings

For string values, you can use the string comparison functions to check how strings compare using Latin collation settings.

Tip

Tip: Any column can be converted to String data type to use these functions.

Include Page
String Collation Rules
String Collation Rules

Available functions: