Longest |
Problem solver for the longest common substring problem, operating in O(N) time (N being the text length), and using an array of linked structures stored in a linear array instead of linked class instances.
This code runs slightly faster than LongestCommonSubstringL, and avoids creating a lot of nodes for the linked list, in order to make it easier for the garbage collector.
Inheritance HierarchySystemObject
Altaxo.Collections.TextLongestCommonSubstringBase
Altaxo.Collections.TextLongestCommonSubstringBaseA
Altaxo.Collections.TextLongestCommonSubstringA
Altaxo.Collections.TextLongestCommonSubstringBase
Altaxo.Collections.TextLongestCommonSubstringBaseA
Altaxo.Collections.TextLongestCommonSubstringA
Namespace: Altaxo.Collections.Text
Assembly: AltaxoCore (in AltaxoCore.dll) Version: 4.8.3179.0 (4.8.3179.0)
SyntaxC#
public class LongestCommonSubstringA : LongestCommonSubstringBaseA
The LongestCommonSubstringA type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | LongestCommonSubstringA | Initializes a new instance of the problem solver for the longest common substring problem. |
Properties| Name | Description | |
|---|---|---|
 | CommonSubstringPositionsForMaximumNumberOfWords | Returns the positions for common substrings for the maximum number of words that have at least one common substring. The result
is identical to a call of GetSubstringPositionsCommonToTheNumberOfWords(Int32) with the argument MaximumNumberOfWordsWithCommonSubstring (Inherited from LongestCommonSubstringBase) |
| MaximumNumberOfWordsWithCommonSubstring | Gets or sets the maximum number of words with a common substring. (Inherited from LongestCommonSubstringBase) |
| StoreVerboseResults | Gets or sets a value indicating whether to store all longest common substrings for a given number of words or just one. (Inherited from LongestCommonSubstringBase) |
Methods| Name | Description | |
|---|---|---|
 | CleanIntermediates | Cleans the intermediates so the garbage collector can get them. |
| Equals | Determines whether the specified object is equal to the current object. (Inherited from Object) |
| Evaluate | Evaluates the longest common substring. After evaluation, the results can be accessed by the properties of this instance. Please be aware that the amount of resulting information depends on the state of [P:StoreVerboseResults]. |
| EvaluateMaximumNumberOfWordsWithCommonSubstring | Posts the process results. Here the maximum number of words that have at least one common substring is evaluated. |
| Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object) |
| GetHashCode | Serves as the default hash function. (Inherited from Object) |
| GetSubstringPositionsCommonToTheNumberOfWords | Returns the positions for common substrings for the given number of words (Inherited from LongestCommonSubstringBase) |
| GetType | Gets the Type of the current instance. (Inherited from Object) |
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object) |
| print_debug | Prints all linked list items for debugging purposes. (Inherited from LongestCommonSubstringBaseA) |
| StoreVerboseResult | Stores a common substring occurence. (Inherited from LongestCommonSubstringBase) |
| ToString | Returns a string that represents the current object. (Inherited from Object) |
Fields| Name | Description | |
|---|---|---|
 | _ddlList | Keeps a linked list of LongestCommonSubstringBaseALLElements. (Inherited from LongestCommonSubstringBaseA) |
| _items | |
| _lastLcp | (Inherited from LongestCommonSubstringBaseA) |
| _LCP |
Stores the length of the Longest Common Prefix of the lexicographically i-th suffix and its lexicographical predecessor (the lexicographically (i-1)-th suffix).
The element at index 0 is always 0.
(Inherited from LongestCommonSubstringBase) |
| _LCPS | Stores the length of the Longest Common Prefix _LCP, but here only if two adjacent suffixes belong to the same word.
In the other case, i.e. the suffix _suffixArray[i-1] belongs to another word than the suffix _suffixArray[i], then _LCPS[i] is zero. (Inherited from LongestCommonSubstringBase) |
| _lcsOfNumberOfWords |
Stores in element idx the length of the longest substring that is common to idx number of words (it follows that index 0 and 1 are unused here).
(Inherited from LongestCommonSubstringBase) |
| _maximumLcp |
Maximum of all values in the _LCP array.
(Inherited from LongestCommonSubstringBase) |
| _maximumNumberOfWordsWithCommonSubstring |
Contains the maximum number of words that have a common substring.
(Inherited from LongestCommonSubstringBase) |
| _numberOfWords | Number of words the text was separated into. (Inherited from LongestCommonSubstringBase) |
| _singleResultOfNumberOfWords |
If _verboseResultsOfNumberOfWords is false, stores only the first report of a longest common string for the given number of words.
The content of one element is the beginning and the end index in the suffix array that indicate all suffixes that have this substring in common.
The length of this substring is stored in _lcsOfNumberOfWords at the same index.
If _verboseResultsOfNumberOfWords is true, this array is not used and is set to null.
(Inherited from LongestCommonSubstringBase) |
| _suffixArray | Maps the lexicographical order position i of a suffix to the starting position of the suffix in the text, which is the value of the i-th element of this array. (Inherited from LongestCommonSubstringBase) |
| _useVerboseResults |
Determines the amount of information to store during evaluation.
(Inherited from LongestCommonSubstringBase) |
| _verboseResultsOfNumberOfWords |
If _verboseResultsOfNumberOfWords is true, this array stores, for a given number of words that have one or more substrings in common, a list with all positions where such common substrings occur.
The content of one element of each list is the beginning and the end index in the suffix array that indicate all suffixes that have a substring in common. The length of this substring is stored in _lcsOfNumberOfWords
If _verboseResultsOfNumberOfWords is false, this array is not used and is set to null.
(Inherited from LongestCommonSubstringBase) |
| _wordIndices |
Maps the lexicographical order position i of a suffix to the index of the word, in which this suffix starts. This means, that for instance the value of the i-th
element contains the index of the word, in which the lexicographically i-th suffix that starts at position _suffixArray[i] begins.
The contents of this array is only meaningful, if you provided text that was separated into words, for instance for the longest common substring problem.
(Inherited from LongestCommonSubstringBase) |
| _wordStartPositions |
Start positions of the words in which the original text was separated in the concenated text array.
(Inherited from LongestCommonSubstringBase) |
Remarks
For details of the algorithm see the very nice paper by Michael Arnold and Enno Ohlebusch, 'Linear Time Algorithms for Generalizations of the Longest Common Substring Problem', Algorithmica (2011) 60; 806-818; DOI: 10.1007/s00453-009-9369-1.
This code was adopted by D.Lellinger from the C++ sources from the web site of the authors at http://www.uni-ulm.de/in/theo/research/sequana.html.
See Also