I'm working on Huffman algorithm right now and I need to write into output file some information (in order to decode what I've got): dictionary (character and its code), number of added zeros (count) and byte array. I tried to do something like this:
public void WriteInFile()
{
using (StreamWriter sw = new StreamWriter("lab1output.txt"))
{
foreach (KeyValuePair<char, string> pair in Coded)
{
sw.WriteLine(pair);
}
sw.WriteLine(count);
}
using (FileStream fs = new FileStream("lab1output.txt", FileMode.Open))
{
byte[] input = bytedList.ToArray();
fs.Write(input, 0, input.Length);
}
}
For example, I wrote 'hello' in my file. In the output file I expect to get this:
[h, 01]
[e, 000]
[l, 1]
[o, 001]
6 (number of added zeros)
F# (encoded string)
But I get this:
F#, 01]
[e, 000]
[l, 1]
[o, 001]
6
Please tell me what's wrong and how I can fix this. Thanks!
Edit:
This is my Dictionary.
public Dictionary<char, string> Coded = new Dictionary<char, string>();
for (int i = 0; i < infoFromFile.Length; i++)
{
encodedSymbol = this.Root.Traverse(infoFromFile[i], new List<bool>()); // Traverse the tree
if (!Coded.ContainsKey(infoFromFile[i]))
{
Coded.Add(infoFromFile[i], null);
foreach (var e in encodedSymbol)
{
Coded[infoFromFile[i]] += ((e ? 1 : 0) + "");
}
}
encodedMessage.AddRange(encodedSymbol);
}
Related
I need to upload array of string to firestore. I need to return list of Strings using single string as input.
If the input is 'Firestore'.
I should return list like this:
[f,fi,fir,firs,first,firsto,firstor,firestore]
If the input is 'Google Cloud'.
I should return list like this:
[g,
go,
goo,
goo,
goog,
googl,
google,
c,
cl,
clo,
clou,
cloud]
For having [g, go, goo, goo, goog, googl, google, c, cl, clo, clou, cloud] as result
use this :
String test = 'Google Cloud';
List<String> chars = [];
for (var word in test.split(" ")) {
for (var i = 0; i <= word.length; i++) {
if (word.substring(0, i).isNotEmpty) {
chars.add(word.substring(0, i));
}
}
}
print(chars);
it's a good practice to share what you have already done. Here is a simple way of achieving what you want (excluding white spaces) :
String test = 'firestore';
List<String> chars = [];
for (var i = 0; i <= test.length; i++) {
if (test.substring(0, i).isNotEmpty) {
chars.add(test.substring(0, i));
}
}
print(chars);
The above prints [f, fi, fir, fire, fires, firest, firesto, firestor, firestore]
My game lets the user modify the terrain at runtime, but now I need to save said terrain. I've tried to directly save the terrain's heightmap to a file, but this takes almost up to two minutes to write for this 513x513 heightmap.
What would be a good way to approach this? Is there any way to optimize the writing speed, or am I approaching this the wrong way?
public static void Save(string pathraw, TerrainData terrain)
{
//Get full directory to save to
System.IO.FileInfo path = new System.IO.FileInfo(Application.persistentDataPath + "/" + pathraw);
path.Directory.Create();
System.IO.File.Delete(path.FullName);
Debug.Log(path);
//Get the width and height of the heightmap, and the heights of the terrain
int w = terrain.heightmapWidth;
int h = terrain.heightmapHeight;
float[,] tData = terrain.GetHeights(0, 0, w, h);
//Write the heights of the terrain to a file
for (int y = 0; y < h; y++)
{
for (int x = 0; x < w; x++)
{
//Mathf.Round is to round up the floats to decrease file size, where something like 5.2362534 becomes 5.24
System.IO.File.AppendAllText(path.FullName, (Mathf.Round(tData[x, y] * 100) / 100) + ";");
}
}
}
As a sidenote, the Mathf.Round doesn't seem to influence the saving time too much, if at all.
You are making a lot of small individual File IO calls. File IO is always time consuming and expensive as it contains opening the file, writing to it, saving the file and closing the file.
Instead I would rather generate the complete string using e.g. a StringBuilder which is also more efficient than using something like
var someString
for(...)
{
someString += "xyz"
}
because the latter always allocates a new string.
Then use e.g. a FileStream and StringWriter.WriteAsync(string) for writing async.
Also rather use Path.Combine instead of directly concatenating string via /. Path.Combine automatically uses the correct connectors according to the OS it is used on.
And instead of FileInfo.Directory.Create rather use Directory.CreateDirectory which doesn't throw an exception if the directory already exists.
Something like
using System.IO;
...
public static void Save(string pathraw, TerrainData terrain)
{
//Get full directory to save to
var filePath = Path.Combine(Application.persistentDataPath, pathraw);
var path = new FileInfo(filePath);
Directory.CreateDirectory(path.DirectoryName);
// makes no sense to delete
// ... rather simply overwrite the file if exists
//File.Delete(path.FullName);
Debug.Log(path);
//Get the width and height of the heightmap, and the heights of the terrain
var w = terrain.heightmapWidth;
var h = terrain.heightmapHeight;
var tData = terrain.GetHeights(0, 0, w, h);
// put the string together
// StringBuilder is more efficient then using
// someString += "xyz" because latter always allocates a new string
var stringBuilder = new StringBuilder();
for (var y = 0; y < h; y++)
{
for (var x = 0; x < w; x++)
{
// also add the linebreak if needed
stringBuilder.Append(Mathf.Round(tData[x, y] * 100) / 100).Append(';').Append('\n');
}
}
using (var file = File.Open(filePath, FileMode.OpenOrCreate, FileAccess.Write))
{
using (var streamWriter = new StreamWriter(file, Encoding.UTF8))
{
streamWriter.WriteAsync(stringBuilder.ToString());
}
}
}
You might want to specify how exactly the numbers shall be printed with a certain precision like e.g.
(Mathf.Round(tData[x, y] * 100) / 100).ToString("0.00000000");
As the picture show , I need to get byte array from ByteRange to do some verify , they are 0 to 840 and 960 to 1200.
I found the similar question : In Itext 7, how to get the range stream to sign a pdf?
iText in its own verification code needs to do the same thing. It does so in its SignatureUtil class. Thus, one can simply borrow from that code, e.g. like this:
try ( PdfReader pdfReader = new PdfReader(SOURCE_PDF);
PdfDocument pdfDocument = new PdfDocument(pdfReader);) {
SignatureUtil signatureUtil = new SignatureUtil(pdfDocument);
for (String name : signatureUtil.getSignatureNames()) {
PdfSignature signature = signatureUtil.getSignature(name);
PdfArray b = signature.getByteRange();
RandomAccessFileOrArray rf = pdfReader.getSafeFile();
try ( InputStream rg = new RASInputStream(new RandomAccessSourceFactory().createRanged(rf.createSourceView(), SignatureUtil.asLongArray(b)));
OutputStream result = TARGET_STREAM_FOR_name_BYTES) {
byte[] buf = new byte[8192];
int rd;
while ((rd = rg.read(buf, 0, buf.length)) > 0) {
result.write(buf, 0, rd);
}
}
}
}
(RetrieveSignedRanges test testExtractSignedBytes)
If you want the byte range as a byte[] in memory, you can use a ByteArrayOutputStream as TARGET_STREAM_FOR_name_BYTES and retrieve the resulting byte array from it.
I have a queue of elements, sorted by date. I need to extract the first n elements, which have the same date and add them to a temporary ArrayList, from which I choose one of them and scrap the others. After that I need to continue doing the same thing for the next n elements of the queue with the same date (extract them to the temp list and so on) until I have no more items in the queue.
// some notes to help you understand the code
PriorityQueue<Results> r, size(4), elementsEqualByTime(1=2,3=4);
List<Comments> c, size(2);
ArrayList temp;
if (c.size() != r.size() && resultIter.hasNext()) {
//first iteration will compare element 0 to itself -> 100% true
ResultObject r2 = resultIter.next();
ResultObject r1 = r2;
while (resultIter.hasNext() && r1.getTime().equals(r2.getTime())) {
temp.add(r1);
//we add the matching elements before we continue
r1 = r2;
temp.add(r1);
if (resultIter.hasNext()) {
//after we add the 2 matching elements we continue
r2 = resultIter.next();
}
}
//use the items in temp
temp.clear();
}
Right now it works for the 1st set of elements, but on the 2nd iteration it adds no elements to the temp ArrayList. I'd appreciate help with this solution, but am also open to different suggestions.
boolean Check (List<Element> elements,Element element)
{
for(Element element1:elements)
if(element1.equals(element))
return true;
return false;
}
void Stuff()
{
// some notes to help you understand the code
PriorityQueue<Element> r = new PriorityQueue<Element>();
List<Element> c;
List<Element> temp = new ArrayList<Element>();
for(Element element:r)
{
if(!Check(temp, element))
{
// do stuff with temp
temp = new ArrayList<Element>();
}
temp.add(element);
}
}
while (commentIter.hasNext()) {
Comment c1 = null;
temp.add(arrayQueue[0]);
for (int i = 1; i < arrayQueue.length; i++) {
if (!arrayQueue[i].getTime().equals(arrayQueue[i - 1].getTime())) {
c1 = commentIter.next();
//do stuff with the results
temp = new HashSet<ResultObject>();
}
temp.add(arrayQueue[i]);
}
if (!temp.isEmpty()) {
c1 = commentIter.next();
//do stuff with the results
}
temp = new HashSet<ResultObject>();
}
That's a tested solution which works.
I am trying to read a xml file from the web and parse it out using XDocument. It normally works fine but sometimes it gives me this error for day:
**' ', hexadecimal value 0x1F, is an invalid character. Line 1, position 1**
I have tried some solutions from Google but they aren't working for VS 2010 Express Windows Phone 7.
There is a solution which replace the 0x1F character to string.empty but my code return a stream which doesn't have replace method.
s = s.Replace(Convert.ToString((byte)0x1F), string.Empty);
Here is my code:
void webClient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
using (var reader = new StreamReader(e.Result))
{
int[] counter = { 1 };
string s = reader.ReadToEnd();
Stream str = e.Result;
// s = s.Replace(Convert.ToString((byte)0x1F), string.Empty);
// byte[] str = Convert.FromBase64String(s);
// Stream memStream = new MemoryStream(str);
str.Position = 0;
XDocument xdoc = XDocument.Load(str);
var data = from query in xdoc.Descendants("user")
select new mobion
{
index = counter[0]++,
avlink = (string)query.Element("user_info").Element("avlink"),
nickname = (string)query.Element("user_info").Element("nickname"),
track = (string)query.Element("track"),
artist = (string)query.Element("artist"),
};
listBox.ItemsSource = data;
}
}
XML file:
http://music.mobion.vn/api/v1/music/userstop?devid=
0x1f is a Windows control character. It is not valid XML. Your best bet is to replace it.
Instead of using reader.ReadToEnd() (which by the way - for a large file - can use up a lot of memory.. though you can definitely use it) why not try something like:
string input;
while ((input = sr.ReadLine()) != null)
{
string = string + input.Replace((char)(0x1F), ' ');
}
you can re-convert into a stream if you'd like, to then use as you please.
byte[] byteArray = Encoding.ASCII.GetBytes( input );
MemoryStream stream = new MemoryStream( byteArray );
Or else you could keep doing readToEnd() and then clean that string of illegal characters, and convert back to a stream.
Here's a good resource for cleaning illegal characters in your xml - chances are, youll have others as well...
https://seattlesoftware.wordpress.com/tag/hexadecimal-value-0x-is-an-invalid-character/
What could be happening is that the content is compressed in which case you need to decompress it.
With HttpHandler you can do this the following way:
var client = new HttpClient(new HttpClientHandler
{
AutomaticDecompression = DecompressionMethods.GZip
| DecompressionMethods.Deflate
});
With the "old" WebClient you have to derive your own class to achieve the similar effect:
class MyWebClient : WebClient
{
protected override WebRequest GetWebRequest(Uri address)
{
HttpWebRequest request = base.GetWebRequest(address) as HttpWebRequest;
request.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
return request;
}
}
Above taken from here
To use the two you would do something like this:
HttpClient
using (var client = new HttpClient(new HttpClientHandler { AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate }))
{
using (var stream = client.GetStreamAsync(url))
{
using (var sr = new StreamReader(stream.Result))
{
using (var reader = XmlReader.Create(sr))
{
var feed = System.ServiceModel.Syndication.SyndicationFeed.Load(reader);
foreach (var item in feed.Items)
{
Console.WriteLine(item.Title.Text);
}
}
}
}
}
WebClient
using (var stream = new MyWebClient().OpenRead("http://myrss.url"))
{
using (var sr = new StreamReader(stream))
{
using (var reader = XmlReader.Create(sr))
{
var feed = System.ServiceModel.Syndication.SyndicationFeed.Load(reader);
foreach (var item in feed.Items)
{
Console.WriteLine(item.Title.Text);
}
}
}
}
This way you also recieve the benefit of not having to .ReadToEnd() since you are working with the stream instead.
Consider using System.Web.HttpUtility.HtmlDecode if you're decoding content read from the web.
If you are having issues replacing the character
For me there were some issues if you try to replace using the string instead of the char. I suggest trying some testing values using both to see what they turn up. Also how you reference it has some effect.
var a = x.IndexOf('\u001f'); // 513
var b = x.IndexOf(Convert.ToString((byte)0x1F)); // -1
x = x.Replace(Convert.ToChar((byte)0x1F), ' '); // Works
x = x.Replace(Convert.ToString((byte)0x1F), " "); // Fails
I blagged this
I had the same issue and found that the problem was a embedded in the xml.
The solution was:
s = s.Replace(" ", " ")
I'd guess it's probably an encoding issue but without seeing the XML I can't say for sure.
In terms of your plan to simply replace the character but not being able to, because you have a stream rather than a text, simply read the stream into a string and then remove the characters you don't want.
Works for me.........
string.Replace(Chr(31), "")
I used XmlSerializer to parse XML and faced the same exception.
The problem is that the XML string contains HTML codes of invalid characters
This method removes all invalid HTML codes from string (based on this thread - https://forums.asp.net/t/1483793.aspx?Need+a+method+that+removes+illegal+XML+characters+from+a+String):
public static string RemoveInvalidXmlSubstrs(string xmlStr)
{
string pattern = "&#((\\d+)|(x\\S+));";
Regex regex = new Regex(pattern, RegexOptions.IgnoreCase);
if (regex.IsMatch(xmlStr))
{
xmlStr = regex.Replace(xmlStr, new MatchEvaluator(m =>
{
string s = m.Value;
string unicodeNumStr = s.Substring(2, s.Length - 3);
int unicodeNum = unicodeNumStr.StartsWith("x") ?
Convert.ToInt32(unicodeNumStr.Substring(1), 16)
: Convert.ToInt32(unicodeNumStr);
//according to https://www.w3.org/TR/xml/#charsets
if ((unicodeNum == 0x9 || unicodeNum == 0xA || unicodeNum == 0xD) ||
((unicodeNum >= 0x20) && (unicodeNum <= 0xD7FF)) ||
((unicodeNum >= 0xE000) && (unicodeNum <= 0xFFFD)) ||
((unicodeNum >= 0x10000) && (unicodeNum <= 0x10FFFF)))
{
return s;
}
else
{
return String.Empty;
}
})
);
}
return xmlStr;
}
Nobody can answer if you don't show relevant info - I mean the Xml content.
As a general advice I would put a breakpoint after ReadToEnd() call. Now you can do a couple of things:
Reveal Xml content to this forum.
Test it using VS Xml visualizer.
Copy-paste the string into a txt file and investigate it offline.