public static string SummarizeByLSA(TextFile textFile)
{
string input = textFile.RawText;
string[] sentences = input.Split(new char[] { '.', '!', '?', ':', '…', '\r', '\n' },
StringSplitOptions.RemoveEmptyEntries);
for (int i = 0; i < sentences.Length; ++i)
{
var sb = new StringBuilder();
string sentence = sentences[i].Trim();
foreach (char c in sentence)
{
if (!char.IsPunctuation(c))
{
sb.Append(c);
}
}
sentences[i] = sb.ToString().ToLower();
}
// Remove stop words--e.g., the, and, a, etc.
string[] stopwords = File.ReadAllLines(@"Resources/stopwords.txt");
for (int i = 0; i < sentences.Count(); ++i)
{
string sentence = sentences[i];
for (int j = 0; j < stopwords.Count(); ++j)
{
sentences[i] = string.Join(" ", sentence.Split(' ').Where(wrd => !stopwords.Contains(wrd)));
}
}
// Reduce words to their stem.
PorterStemmer stemmer = new PorterStemmer();
for (int i = 0; i < sentences.Count(); ++i)
{
sentences[i] = stemmer.StemWord(sentences[i]);
}
Dictionary <string, int> wordFrequencies = new Dictionary <string, int>();
foreach (string s in sentences)
{
string[] words = s.Split(' ');
foreach (string w in words)
{
if (wordFrequencies.ContainsKey(w))
{
wordFrequencies[w] += 1;
}
else
{
wordFrequencies[w] = 1;
}
}
}
// Top N words with highest frequencies will serve as document concepts.
int N = textFile.DesiredSummaryLength;
string[] concepts = (from kvp in wordFrequencies
orderby kvp.Value descending
select kvp)
.ToDictionary(pair => pair.Key, pair => pair.Value).Take(N)
.Select(k => k.Key).ToArray();
// Add concepts to TextFile instance properties.
textFile.DocumentConcepts = concepts;
int documentLength = sentences.Length;
var X = DenseMatrix.Create(N, documentLength, (i, j) => 0.0);
for (int i = 0; i < X.RowCount; ++i)
{
int sentencesWithConcept = 0;
string concept = concepts[i];
for (int j = 0; j < X.ColumnCount; ++j)
{
string[] sentenceWords = sentences[j].Split(' ');
int wordCount = (from word in sentenceWords
where word == concept
select word)
.Count();
if (wordCount > 0)
{
sentencesWithConcept += 1;
}
X[i, j] = wordCount / sentenceWords.Length;
}
if (sentencesWithConcept == 0)
{
Console.WriteLine("No sentences with concept " + concepts[i]);
}
double inverseDocumentFreq = Math.Log(documentLength / (sentencesWithConcept + 0.0001), 2.0);
for (int k = 0; k < X.ColumnCount; ++k)
{
X[i, k] = X[i, k] * inverseDocumentFreq;
}
}
// Compute SVD of the topic representation matrix, X.
var svd = X.Svd();
// Cross method to select summary sentences.
int columnCount = svd.VT.ColumnCount;
Matrix <double> Vh = svd.VT.SubMatrix(0, concepts.Length, 0, columnCount).PointwiseAbs();
for (int i = 0; i < Vh.RowCount; ++i)
{
double averageSentenceScore = Vh.Row(i).Average();
for (int j = 0; j < Vh.ColumnCount; ++j)
{
if (Vh[i, j] <= averageSentenceScore)
{
Vh[i, j] = 0;
}
}
}
var sentenceLengths = Vh.RowSums();
int[] summaryIndices = new int[Vh.RowCount];
Console.Write("Vh.RowCnt = ", Vh.RowCount);
Console.Write("concepts.Length = ", concepts.Length);
for (int i = 0; i < Vh.RowCount; ++i)
{
double max = 0;
for (int j = 0; j < Vh.ColumnCount; ++j)
{
if (Vh[i, j] > max)
{
max = Vh[i, j];
summaryIndices[i] = j;
}
}
}
string[] sourceSentences = Regex.Split(input, @"(?<=[\.!\?])\s+");
textFile.DocumentLength = sourceSentences.Length;
string summary = "";
foreach (int i in summaryIndices)
{
summary += sourceSentences[i] + " ";
}
/* From https://bit.ly/3ogjy2l */
return(summary.Replace("\r\n", string.Empty)
.Replace("\n", string.Empty)
.Replace("\r", string.Empty)
.Replace("\t", string.Empty)
.Replace(((char)0x2028).ToString(), string.Empty)
.Replace(((char)0x2029).ToString(), string.Empty));
}
private void ProcessSelectedFiles(string[] fileNames)
{
/*
* Handle improper file types
*/
Form wf = new Form()
{
Size = new System.Drawing.Size(0, 0)
};
Task.Delay(TimeSpan.FromSeconds(7))
.ContinueWith((t) => wf.Close(), TaskScheduler.FromCurrentSynchronizationContext());
if (fileNames.Length == 1)
{
string fileExt = System.IO.Path.GetExtension(fileNames[0]);
if (fileExt == ".docx" || fileExt == ".odt" || fileExt == ".pdf")
{
AddProperties_Button.Visibility = Visibility.Visible;
}
else if (fileExt == ".txt" /* Txt file properties cannot be updated */)
{
AddProperties_Button.Visibility = Visibility.Hidden;
}
else
{
string message = "Unsupported file type selected: " + fileExt +
"\nType must be .docx, .pdf, .odt, or .txt";
string caption = "Unsupported file type...";
System.Windows.Forms.MessageBox.Show(wf, message, caption);
return;
}
_activeTextFile = new TextFile(fileNames[0]);
_activeTextFile.DesiredSummaryLength = _desiredSummaryLength;
GenerateAndPrintSummary(_activeTextFile);
Regen_Button.Visibility = Visibility.Visible;
DragAndDrop.Visibility = Visibility.Hidden;
Copy_Button.Visibility = Visibility.Visible;
Clear_Button.Visibility = Visibility.Visible;
}
else if (fileNames.Length > 1)
{
string overallSummary = "";
string overallPath = System.IO.Path.GetDirectoryName(fileNames[0]);
foreach (string filePath in fileNames)
{
string fileExt = "";
try
{
fileExt = System.IO.Path.GetExtension(filePath);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
// Handle invalid file types
if (!"docx|odt|pdf|txt".Contains(fileExt))
{
continue;
}
_activeTextFile = new TextFile(filePath);
overallSummary += Summarizer.SummarizeByLSA(_activeTextFile);
}
if (overallSummary.Length == 0)
{
string message = "No supported file types were selected. " +
"\nType must be .docx, .pdf, .odt, or .txt";
string caption = "Unsupported file types...";
System.Windows.Forms.MessageBox.Show(wf, message, caption);
return;
}
_activeTextFile = new TextFile
{
RawText = overallSummary,
Name = overallPath,
FullPath = overallPath,
Extension = null
};
GenerateAndPrintSummary(_activeTextFile);
}
}
