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• Resizing an Binarized image in C#

  - by mouthpiec

  Hi, I have the following code to resize a Binarized image (hence pixel value is 0[black] or 255[white]) with the following code Bitmap ResizedCharImage = new Bitmap(newwidth, newheight); using (Graphics g = Graphics.FromImage((Image)ResizedCharImage)) { g.CompositingQuality = CompositingQuality.HighQuality; g.InterpolationMode = InterpolationMode.HighQualityBilinear; g.SmoothingMode = SmoothingMode.HighQuality; g.PixelOffsetMode = PixelOffsetMode.HighQuality; g.DrawImage(CharBitmap, new Rectangle(0, 0, newwidth, newheight), new Rectangle(0, 0, CharBitmap.Width, CharBitmap.Height), GraphicsUnit.Pixel); } The problem that I am having is that when resizing (i am enlarging the image) some of the pixel values become 254, 253, 1, 2 etc. I need that this do not occur. Is this possible, maybe by changing one of the Graphins properties?

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• is there a such thing as a randomly accessible pseudo-random number generator? (preferably open-sour

  - by lucid

  first off, is there a such thing as a random access random number generator, where you could not only sequentially generate random numbers as we're all used to, assuming rand100() always generates a value from 0-100: for (int i=0;i<5;i++) print rand100() output: 14 75 36 22 67 but also randomly access any random value like: rand100(0) would output 14 as long as you didn't change the seed rand100(3) would always output 22 rand100(4) would always output 67 and so on... I've actually found an open-source generator algorithm that does this, but you cannot change the seed. I know that pseudorandomness is a complex field; I wouldn't know how to alter it to add that functionality. Is there a seedable random access random number generator, preferably open source? or is there a better term for this I can google for more information? if not, part 2 of my question would be, is there any reliably random open source conventional seedable pseudorandom number generator so I could port it to multiple platforms/languages while retaining a consistent sequence of values for each platform for any given seed?

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• Convert any currency string to double

  - by James

  I need to store multiple currencies in SQL server. I understand that SQL won't support all different types of currencies (unless I store it as a string, but I don't want to do that). My idea was to convert all the values from their currency format to a standard double and store that instead. Then just re-format based on the culture info when displaying. However, I have tried doing something like e.g. var cultureInfo = new System.Globalization.CultureInfo("en-US"); double plain = return Double.Parse("$20,000.00", cultureInfo); This doesn't ever seem to work it always throws a FormatException. Even removing the currency symbol and just trying to do this based on the number alone does the same thing. This is just an example I want to support pretty much any type of currency. Is there a standard way of stripping out currency and getting the value as a double?

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• Implementing password hashing/salting algorithm from crackstation.net

  - by Mason240

  I am trying to implement a password hashing/salting algorithm from crackstation.net, but I am unsure how implement it. Storing the password upon user registration seems to be as simple as passing the password into create_hash(). $password = create_hash($_POST['Password']; I'm not following how to validate upon user login. validate_password($password, $good_hash) returns either true or false, and takes $password as parameter, so it seems like a no brainer except for the second parameter $good_hash. Where does this param come from? It is my understanding that password is turned into a hash value every time its used, and that the hash value is what is stored and compared. So why would I have both the $password and $good_hash values? Quick overview of the functions: function create_hash($password){ calls pbkdf2() } function validate_password($password, $good_hash){ calls pbkdf2() calls slow_equals() } function slow_equals($a, $b){ } function pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output = false){ } Of course a different, better method for this would also be just as helpful. Thank you

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• Inserting multiple types into an SQLite database with Python

  - by mankoff

  I'm trying to create an SQLite 3 database from Python. I have a few types I'd like to insert into each record: A float, and then 3 groups of n floats, currently a tuple but could be an array or list.. I'm not well-enough versed in Python to understand all the differences. My problem is the INSERT statement. DAS = 12345 lats = (42,43,44,45) lons = (10,11,12,13) times = (1,2,3,4,5,6,7,8,9) import sqlite3 connection = sqlite3.connect("test.db") cursor = connection.cursor() cursor.execute( "create table foo(DAS LONG PRIMARY KEY,lats real(4),lons real(4), times real(9) )" ) I'm not sure what comes next. Something along the lines of: cmd = 'INSERT into foo values (?,?,?,?), ..." cursor.execute(cmd) How should I best build the SQL insert command given this data?

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• JLayeredPane versus Container layering

  - by Gili

  JLayeredPane allows one to stack multiple Components on top of one another using JLayeredPane.add(Component, Integer). Components in higher "layers" display on top of Components in lower "layers". Container.add(Component, int) provides a similar mechanism whereby Components with lower indexes display on top of Components with higher indexes. Please note that the first mechanism uses Integer and the second mechanism uses int. Also, one renders high values on top of low ones, and the other does the opposite. Do not mix the two :) My question is: what's the point of using JLayeredPane when Container already provides the same mechanism? Does one layer components better than the another? UPDATE: There is also Container.setComponentZOrder(Component, int) to consider.

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• Java Regex for matching quoted string with escaped quotes

  - by kayahr

  I know there are already many questions like mine but I found no answer which works in Java. So I write a new question. I have text files with content like this: key1 = "This is a \"test\" text with escapes using '\\' characters"; key2 = 'It must work with \'single\' quotes and "double" quotes'; I need a regular expression which matches the values in the double-quotes (or single-quotes). This regular expression must support the escaped quotes and escaped backslashes. The regular expression must work with Java standard Pattern/Matcher classes.

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• WPF Animate a Matrix using interpolation

  - by Mark

  I'm having a issue with my application that is using touch gestures to scale, translate and rotate my scene. I was using a TransformGroup which contained TranslateTransform, ScaleTransform and a RotateTransform but I could not get the movement correct, it always jumps and skips, so I moved to a MaxtrixTransform which I was able to use much easier to get my scene to be zoomable, rotatable and panable nicely. However, what I later found out was that you cannot animate smoothly (using interpolation) the values of a Matrix, for what reason I have no idea, but its part of the MSDN doco and the properties of the Matrix are not dependency properties anyways... Has anyone had any luck animating a matrix to make it smooth? The only idea(s) I have had is to animate a few different, custom DP which all have callbacks that I update the matrix from OR To convert the matrix to a set of Transform objects that I then animate and then afterwords convert back. Is there a smarter way to do this?

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• convolution in R

  - by user236215

  I tried to do convolution in R directly and using FFTs then taking inverse. But it seems from simple observation it is not correct. Look at this example: # DIRECTLY > x2$xt [1] 24.610 24.605 24.610 24.605 24.610 > h2$xt [1] 0.003891051 0.003875910 0.003860829 0.003845806 0.003830842 > convolve(h2$xt,x2$xt) [1] 0.4750436 0.4750438 0.4750435 0.4750437 0.4750435 # USING INVERSE FOURIER TRANSFORM > f=fft(fft(h2$xt)*fft(x2$xt), inv=TRUE) > Re(f)/length(f) [1] 0.4750438 0.4750435 0.4750437 0.4750435 0.4750436 > Lets take the index 0. At 0, the convolution should simply be the last value of x2$xt (24.610) multiplied by first value of h2$xt (0.003891051) which should give convolution at index 0 = 24.610*0.003891051 = 0.09575877 which is way off from 0.4750436. Am I doing something wrong? Why is the values so different from expected?

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• Open GL ES 2.0 co-ordinate systems

  - by Chris

  Hi, I want to use Open GL ES 2.0 for a new game, but I have two questions. Q: The first is how do I set up perspective views in Open GL ES 2.0 - do I need to include Open GL ES 1.0 and use glOrtho, or is there a new way? Q: I want to use the 4th quadrant of a Cartesian co-ordinate system for my game and not use -0.5 to +0.5 for values on screen, how once the first question is answered can I achieve this? Other resources: http://iphonedevelopment.blogspot.com/2009/04/opengl-es-from-ground-up-part-3.html Thanks Chris

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• Mathematica Plot3D does not produce a plot when graphing a user-defined function?

  - by pythonscript

  I'm writing a simple Mathematica implementation of the black-scholes model and using Plot3D to plot the pricing surface. However, when I run this code, no plot is produced. My call and put functions to produce correct values when run separately, but no plot is produced. Code: Clear[d1, d2, call, put, stockPrice, strikePrice, riskFreeRate, timeToExp, volatility] d1[stockPrice_, strikePrice_, riskFreeRate_, timeToExp_, volatility_] := (Log[stockPrice / strikePrice] + (riskFreeRate + 0.5*volatility^2)*timeToExp) / (volatility * Sqrt[timeToExp]) d2[stockPrice_, strikePrice_, riskFreeRate_, timeToExp_, volatility_] := d1[stockPrice, strikePrice, riskFreeRate, timeToExp, volatility] - volatility*Sqrt[timeToExp] call[stockPrice_, strikePrice_, riskFreeRate_, timeToExp_, volatility_] := stockPrice * CDF[NormalDistribution[0, 1], d1[stockPrice, strikePrice, riskFreeRate, timeToExp, volatility]] - strikePrice * Exp[-riskFreeRate*timeToExp] *CDF[NormalDistribution[0, 1], d2[stockPrice, strikePrice, riskFreeRate, timeToExp, volatility]] Plot3D[call[stockPrice, 500, 0.0030, timeToExp, 0.39], {stockPrice, 10, 1000}, {timetoExp, 0.0833333, 5}] Other plots, like this sample from the reference, do work. Plot3D[{x^2 + y^2, -x^2 - y^2}, {x, -2, 2}, {y, -2, 2}, RegionFunction -> Function[{x, y, z}, x^2 + y^2 <= 4], BoxRatios -> Automatic]

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• How does Bitmap.Save(Stream, ImageFormat) format the data?

  - by Matt Jacobsen

  I have a non transparent, colour bitmap with length 2480 and width 3507. Using Bitmap.GetPixel(int x, int y) I am able to get the colour information of each pixel in the bitmap. If I squirt the bitmap into a byte[]: MemoryStream ms = new MemoryStream(); bmp.Save(ms, ImageFormat.Bmp); ms.Position = 0; byte[] bytes = ms.ToArray(); then I'd expect to have the same information, i.e. I can go to bytes[1000] and read the colour information for that pixel. It turns out that my array of bytes is larger than I anticipated. I thought I'd get an array with 2480 x 3507 = 8697360 elements. Instead I get an array with 8698438 elements - some sort of header I presume. In what format the bytes in my array stored? Is there a header 1078 bytes long followed by Alpha, Red, Green, Blue values for every byte element, or something else?

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• Weighted Average with LINQ

  - by jsmith

  My goal is to get a weighted average from one table, based on another tables primary key. Example Data: Table1 Key WEIGHTED_AVERAGE 0200 0 Table2 ForeignKey LENGTH PCR 0200 105 52 0200 105 60 0200 105 54 0200 105 -1 0200 47 55 I need to get a weighted average based on the length of a segment and I need to ignore values of -1. I know how to do this in SQL, but my goal is to do this in LINQ. It looks something like this in SQL: SELECT Sum(t2.PCR*t2.LENGTH)/Sum(t2.LENGTH) AS WEIGHTED_AVERAGE FROM Table1 t1, Table2 t2 WHERE t2.PCR <> -1 AND t2.ForeinKey = t1.Key; I am still pretty new to LINQ, and having a hard time figuring out how I would translate this. The result weighted average should come out to roughly 55.3. Thank you.

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• MS Sql Full-text search vs. LIKE expression

  - by Marks

  Hi. I'm currently looking for a way to search a big database (500MB - 10GB or more on 10 tables) with a lot of different fields(nvarchars and bigints). Many of the fields, that should be searched are not in the same table. An example: A search for '5124 Peter' should return all items, that ... have an ID with 5124 in it, have 'Peter' in the title or description have item type id with 5124 in it created by a user named 'peter' or a user whose id has 5124 in it created by a user with '5124' or 'peter' in his street address. How should i do the search? I read that the full-text search of MS-Sql is a lot more performant than a query with the LIKE keyword and i think the syntax is more clear, but i think it cant search on bigint(id) values and i read it has performance problems with indexing and therefore slows down inserts to the DB. In my project there will be more inserting than reading, so this could be a matter. Thanks in advance, Marks

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• Identifying that a variable is a new-style class in Python?

  - by Dave Johansen

  I'm using Python 2.x and I'm wondering if there's a way to tell if a variable is a new-style class? I know that if it's an old-style class that I can do the following to find out. import types class oldclass: pass def test(): o = oldclass() if type(o) is types.InstanceType: print 'Is old-style' else: print 'Is NOT old-style' But I haven't been able to find anything that works for new-style classes. I found this question, but the proposed solutions don't seem to work as expected, because simple values as are identified as classes. import inspect def newclass(object): pass def test(): n = newclass() if inspect.isclass(n): print 'Is class' else: print 'Is NOT class' if inspect.isclass(type(n)): print 'Is class' else: print 'Is NOT class' if inspect.isclass(type(1)): print 'Is class' else: print 'Is NOT class' if isinstance(n, object): print 'Is class' else: print 'Is NOT class' if isinstance(1, object): print 'Is class' else: print 'Is NOT class' So is there anyway to do something like this? Or is everything in Python just a class and there's no way to get around that?

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• geom_tile heatmap with different high fill colours based on factor

  - by Michael

  I'm interested in building a heatmap with geom_tile in ggplot2 that uses a different gradient high color based on a factor. The plot below creates the plot where the individual tiles are colored blue or red based on the xy_type, but there is no gradient. ggplot() + geom_tile(data=mydata, aes(x=factor(myx), y=myy, fill=factor(xy_type))) + scale_fill_manual(values=c("blue", "red")) The plot below does not use the xy_type factor to choose the color, but I get a single group gradient based on the xy_avg_value. ggplot() + geom_tile(data=mydata, aes(x=factor(myx), y=myy, fill=xy_avg_value)) Is there a technique to blend these two plots? I can use a facet_grid(xy_type ~ .) to create separate plots of this data, with the gradient. As this is ultimately going to be a map (x~y coordinates), I'd like to find a way to display the different gradient together in a single geom_tile map.

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• Return value from ajax call?

  - by Dan

  Hi, I'm making a basic ajax function in jquery which echoes the number of rows found in a MySQL Query. function checkEventIDClass(id) { var params = 'method=checkEventIDClash&table=test&id=' + id; $.ajax({ type: "POST", url: "ajax.php", data: params, success: function(result){ return result; } }); } Is it possible to use this returned value in another function? I have tried but only get undefined values. In this situation, it will be acceptable to use synchronous calls. Any advice appreciated. Thanks

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• Good .NET library for fast streaming / batching trigonometry (Atan)?

  - by Sean

  I need to call Atan on millions of values per second. Is there a good library to perform this operation in batch very fast. For example, a library that streams the low level logic using something like SSE? I know that there is support for this in OpenCL, but I would prefer to do this operation on the CPU. The target machine might not support OpenCL. I also looked into using OpenCV, but it's accuracy for Atan angles is only ~0.3 degrees. I need accurate results.

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• Multline Text in a WPF Button through C#

  - by Paul

  How do I get multi-line text on a WPF Button using only C#? I have seen examples of using <LineBreak/> in XAML, but my buttons are created completely programmatically in C#. The number and labels on the buttons correspond to values in the domain model, so I don't think I can use XAML to specify this. I have tried the naive approach below, but it does not work. Button b = new Button(); b.Content = "Two\nLines"; or b.Content = "Two\r\nLines"; In either case, all i see is the first line ("Two") of the text.

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• Determine Click-thru Percentage With PHP

  - by Lea

  Hi all, I am currently working on a small sponsorship application(PHP/MySql) for my personal blog, and am almost finish, but I am stuck on how to calculate the click-thru rate of my sponsors campaigns. I was always terrible with working out percentages, so any practical help would be appreciated. The data is stored in the DB as simple numbers.. So as expected, when a page refreshes, or a sponsors ad is clicked, the data updates with an incrementation of 1. So using these values...say $clicks and $impressions, how would I determine the click-thru rate? What would be the sum I would use to calculate? An example function would really be appreciated. Kind Regards, Lea

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• perl array of array of hashes sorting

  - by srk

  @aoaoh; $aoaoh[0][0]{21} = 31; $aoaoh[0][0]{22} = 31; $aoaoh[0][0]{23} = 17; for $k(0.. $#aoaoh) { for $i(0.. $#aoaoh) { for $val (keys %{$aoaoh[$i][$k]}) { print "$val=$aoaoh[$i][$k]{$val}"; print "\n"; }} } output is 22=31 21=31 23=17 but i expect it to be 21=31 22=31 23=17 Please tell me where is this wrong.. Also how do i sort the values so that i get the output as 23=17 22=31 21=31 (if 2 keys have same value then key with higher value come first)

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• Model Binding using ASP.NET MVC, getting datainput to the controller.

  - by Calibre2010

  Pretty Basic one here guys. I have a View which holds 2 textfields for input and a submit button <%using (Html.BeginForm("DateRetrival", "Home", FormMethod.Post)){ %> <%=Html.TextBox("sday")%> <%=Html.TextBox("eday")%> <input type="submit" value="ok" id="run"/> <% }%> the following controller action which I want to bind the data input is as follows [AcceptVerbs(HttpVerbs.Get)] public ActionResult DateRetrival() { return View(); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult DateRetrival(string submit) { return null; } When I debug this and look in the action methods parameter, the value is null. When I've entered values in both textboxes and and clicked the submit method.

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• C language preprocessor behavior

  - by khanna_param

  There are different kind of macros in C language, nested macro is one of them. Considering a program with the following macro #define HYPE(x,y) (SQUR(x)+SQUR(y)) #define SQUR(x) (x*x) Using this we can successfully compile to get the result. As we all know the C preprocessor replaces all the occurrence of the identifiers with the replacement-string. Considering the above example I would like to know how many times the C preprocessor traverses the program to replace the macro with the replacement values. I assume it cannot be done in one go.

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• Import a Collada model doesn't align to pixels

  - by Dan Friedman

  Assume I have a model that is simply a cube. (It is more complicated than a cube, but for the purposes of this discussion, we will simplify.) So when I am in Sketchup, the cube is Xmm by Xmm by Xmm, where X is an integer. I then export the a Collada file and subsequently load that into threejs. Now if I look at the geometry bounding box, the values are floats, not integers. So now assume I am putting cubes next to each other with a small space in between say 1 pixel. Because screens can't draw half pixels, sometimes I see one pixel and sometimes I see two, which causes a lack of uniformity. I think I can resolve this satisfactorily if I can somehow get the imported model to have integer dimensions. I have full access to all parts of the model starting with Sketchup, so any point in the process is fair game. Is it possible? Thanks.

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• Converting IPv4 or IPv6 address to a long for comparisons

  - by Justin Akehurst

  In order to check if an IPv4 or IPv6 address is within a certain range, I've got code that takes an IPv4 address, turns that into a long, then does that same conversion on the upper/lower bound of the subnet, then checks to see if the long is between those values. I'd like to be able to do the same thing for IPv6, but saw nothing in the Python 2.6 standard libraries to allow me to do this, so I wrote this up: import socket, struct from array import array def ip_address_to_long(address): ip_as_long = None try: ip_as_long = socket.ntohl(struct.unpack('L', socket.inet_pton(socket.AF_INET, address))[0]) except socket.error: # try IPv6 try: addr = array('L', struct.unpack('!4L', socket.inet_pton(socket.AF_INET6, address))) addr.reverse() ip_as_long = sum(addr[i] << (i * 32) for i in range(len(addr))) except socket.error as se: raise ValueError('Invalid address') except Exception as e: print str(e) return ip_as_long My question is: Is there a simpler way to do this that I am missing? Is there a standard library call that can do this for me?

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