Wildcard search Leave feedback
Wildcard search allows you to search for words with unknown letters or ranges of letters.
In a search query in text form, there are 2 forms of wildcard characters:
- ? for a single character;
- ?(n~m) for a group of characters, where n and m are numbers from 0 to 255, and n <= m.
Wildcard search is similar to regular expression search, but it works significantly faster when there are fewer groups of wildcard characters and they are closer to the end of a search query.
Wildcard search is flexible enough to be used for prefix queries, since a prefix query is a special case of a wildcard query. Since version 26.10, wildcard search uses as many threads as there are processor cores by default.
Examples of wildcard search with queries in text form are presented below.
import os
from groupdocs.search import Index
# Creating an index in the specified folder
index = Index("./index")
# Indexing documents from the specified folder
index.add("./documents")
# Search in the index
result1 = index.search("m?rry") # Search for 'merry', 'marry', etc.
result2 = index.search("card?(1~6)") # Search for 'cardiff', 'cardinal', 'cardio', 'cards', etc.
# Printing the words found
for query, result in (("m?rry", result1), ("card?(1~6)", result2)):
print(query, "- documents found:", result.document_count)
for document in result:
print(" ", os.path.basename(document.document_info.file_path), document.terms)
The following sample files are used in this example: documents/word-games.txt, documents/zoo-guide.txt
m?rry - documents found: 1
word-games.txt ['marry', 'merry']
card?(1~6) - documents found: 1
word-games.txt ['cardiff', 'cardinal', 'cardio', 'cards']
To build a query for the wildcard search in object form, use the WordPattern class. This class contains the following methods for adding known parts of a word and wildcards to a pattern:
- append_string appends a string of known characters.
- append_character appends a known character.
- append_one_character_wildcard appends a wildcard for exactly one character (? in text form).
- append_zero_or_one_character_wildcard appends a wildcard for zero or one character (?(0~1) in text form).
- append_zero_or_more_characters_wildcard appends a wildcard for zero to 255 characters (?(0~255) in text form).
- append_one_or_more_characters_wildcard appends a wildcard for one to 255 characters (?(1~255) in text form).
- append_wildcard appends a wildcard for the specified minimum and maximum numbers of characters (?(min~max) in text form). Both values must be in the range from 0 to 255, and the minimum must not be greater than the maximum; otherwise, ArgumentOutOfRangeException is thrown (ValueError in Python).
The known characters are converted to lower case, since words are stored in the index in lower case. An example of constructing a query in object form is presented below.
import os
from groupdocs.search import Index, SearchQuery
from groupdocs.search.common import WordPattern
# Creating an index in the specified folder
index = Index("./index")
# Indexing documents from the specified folder
index.add("./documents")
# Search with pattern "m?rry"
# Search for 'merry', 'marry', etc.
pattern1 = WordPattern()
pattern1.append_string("m")
pattern1.append_one_character_wildcard()
pattern1.append_string("rry")
query1 = SearchQuery.create_word_pattern_query(pattern1)
result1 = index.search(query1)
# Search with pattern "card?(1~6)"
# Search for 'cardiff', 'cardinal', 'cardio', 'cards', etc.
pattern2 = WordPattern()
pattern2.append_string("card")
pattern2.append_wildcard(1, 6)
query2 = SearchQuery.create_word_pattern_query(pattern2)
result2 = index.search(query2)
# Printing the words found
for pattern, result in ((pattern1, result1), (pattern2, result2)):
print(pattern.to_string(), "- documents found:", result.document_count)
for document in result:
print(" ", os.path.basename(document.document_info.file_path), document.terms)
The following sample files are used in this example: documents/word-games.txt, documents/zoo-guide.txt
m?rry - documents found: 1
word-games.txt ['marry', 'merry']
card?(1~6) - documents found: 1
word-games.txt ['cardiff', 'cardinal', 'cardio', 'cards']
You may easily run the code from documentation articles and see the features in action in our GitHub examples:
Along with the full-featured library, we provide simple but powerful free apps.
You are welcome to search over your PDF, DOC, DOCX, PPT, PPTX, XLS, XLSX and more with our free online Free Online Document Search App.
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