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Pedram_Parsian
با سلام
می خواستم ببینم مرتب سازی خارجی چه جوری توی سی شارپ انجام میشه ؟
ممنون میشم یه منبع یا سورس و ... معرفی کنید.
با تشکر
بدون شرح :
..............
static void Split(string file)
{
int split_num = 1;
StreamWriter sw = new StreamWriter(
string.Format("c:\\split{0:d5}.dat", split_num));
long read_line = 0;
using (StreamReader sr = new StreamReader(file))
{
while (sr.Peek() >= 0)
{
// Progress reporting
if (++read_line % 5000 == 0)
Console.Write("{0:f2}% \r",
100.0 * sr.BaseStream.Position / sr.BaseStream.Length);
// Copy a line
sw.WriteLine(sr.ReadLine());
// If the file is big, then make a new split,
// however if this was the last line then don't bother
if (sw.BaseStream.Length > 100000000 && sr.Peek() >= 0)
{
sw.Close();
split_num++;
sw = new StreamWriter(
string.Format("c:\\split{0:d5}.dat", split_num));
}
}
}
sw.Close();
}
.........
static void SortTheChunks()
{
foreach (string path in Directory.GetFiles("C:\\", "split*.dat"))
{
// Read all lines into an array
string[] contents = File.ReadAllLines(path);
// Sort the in-memory array
Array.Sort(contents);
// Create the 'sorted' filename
string newpath = path.Replace("split", "sorted");
// Write it
File.WriteAllLines(newpath, contents);
// Delete the unsorted chunk
File.Delete(path);
// Free the in-memory sorted array
contents = null;
GC.Collect();
}
}
..................
static void MergeTheChunks()
{
string[] paths = Directory.GetFiles("C:\\", "sorted*.dat");
int chunks = paths.Length; // Number of chunks
int recordsize = 100; // estimated record size
int records = 10000000; // estimated total # records
int maxusage = 500000000; // max memory usage
int buffersize = maxusage / chunks; // bytes of each queue
double recordoverhead = 7.5; // The overhead of using Queue<>
int bufferlen = (int)(buffersize / recordsize /
recordoverhead); // number of records in each queue
// Open the files
StreamReader[] readers = new StreamReader[chunks];
for (int i = 0; i < chunks; i++)
readers[i] = new StreamReader(paths[i]);
// Make the queues
Queue<string>[] queues = new Queue<string>[chunks];
for (int i = 0; i < chunks; i++)
queues[i] = new Queue<string>(bufferlen);
// Load the queues
for (int i = 0; i < chunks; i++)
LoadQueue(queues[i], readers[i], bufferlen);
// Merge!
StreamWriter sw = new StreamWriter("C:\\BigFileSorted.txt");
bool done = false;
int lowest_index, j, progress = 0;
string lowest_value;
while (!done)
{
// Report the progress
if (++progress % 5000 == 0)
Console.Write("{0:f2}% \r",
100.0 * progress / records);
// Find the chunk with the lowest value
lowest_index = -1;
lowest_value = "";
for (j = 0; j < chunks; j++)
{
if (queues[j] != null)
{
if (lowest_index < 0 ||
String.CompareOrdinal(
queues[j].Peek(), lowest_value) < 0)
{
lowest_index = j;
lowest_value = queues[j].Peek();
}
}
}
// Was nothing found in any queue? We must be done then.
if (lowest_index == -1) { done = true; break; }
// Output it
sw.WriteLine(lowest_value);
// Remove from queue
queues[lowest_index].Dequeue();
// Have we emptied the queue? Top it up
if (queues[lowest_index].Count == 0)
{
LoadQueue(queues[lowest_index],
readers[lowest_index], bufferlen);
// Was there nothing left to read?
if (queues[lowest_index].Count == 0)
{
queues[lowest_index] = null;
}
}
}
sw.Close();
// Close and delete the files
for (int i = 0; i < chunks; i++)
{
readers[i].Close();
File.Delete(paths[i]);
}
}
static void LoadQueue(Queue<string> queue,
StreamReader file, int records)
{
for (int i = 0; i < records; i++)
{
if (file.Peek() < 0) break;
queue.Enqueue(file.ReadLine());
}
}
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