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Sybase: how can I remove non-printable characters from CHAR or VARCHAR fields with SQL?

- by Kenny Drobnack

I'm working with a Sybase database that seems to have non-printable characters in some of the string fields and this is throwing off some of our processing code. At first glance, it seemed to only be newlines and carriage returns, but we also have an ASCII code 27 in there - an ESC character, some accented characters, and some other oddities in there. I have no direct access to change the database, so changing the bad data isn't an option, yet. For now I have to make do with just filtering it out. We're trying to export the table data from one database and load it into a database used by another application in a nightly batch process. Ideally, I'd like to have a function that I can pass a list of characters and just have Sybase return the data with those characters removed. I'd like to keep it something we could do in plain SQL if possible. Something like this to remove characters that are ASCII 0 - 31. select str_replace(FIELD1, (0-31), NULL) as FIELD1, str_replace(FIELD2, (0-31), NULL) as FIELD2 from TABLE So far, str_replace is the nearest I can find, but it only allows replacing one string with another. No support for character ranges and won't let me do the above. We're running on Sybase ASE 12.5 on Unix servers.

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Connecting repeatable and non-repeatble backgrounds without a seam

- by Stiggler

I have a 700x300 background repeating seamlessly inside of the main content-div. Now I'd like to attach a div at the bottom of the content-div, containing a different background image that isn't repeatable, connecting seamlessly with the repeatable background above it. Essentially, the non-repeatable image will look like the end piece of the repeatable image. Due to the nature of the pattern, unless the full 300px height of the background image is visible in the last repeat of the content-div's backround, the background in the div below won't seamlessly connect. Basically, I need the content div's height to be a multiple of 300px under all circumstances. What's a good approach to this sort of problem? I've tried resizing the content-div on loading the page, but this only works as long as the content div doesn't contain any resizing, dynamic content, which is not my case: function adjustContentHeight() { // Setting content div's height to nearest upper multiple of column backgrounds height, // forcing it not to be cut-off when repeated. var contentBgHeight = 300; var contentHeight = $("#content").height(); var adjustedHeight = Math.ceil(contentHeight / contentBgHeight); $("#content").height(adjustedHeight * contentBgHeight); } $(document).ready(adjustContentHeight); What I'm looking for there is a way to respond to a div resizing event, but there doesn't seem to be such a thing. Also, please assume I have no access to the JS controlling the resizing of content in the content-div, though this is potentially a way of solving the problem. Another potential solution I was thinking off was to offset the background image in the bottom div by a certain amount depending on the height of the content-div. Again, the missing piece seems to be the ability to respond to a resize event.

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Telephone Number to Geolocation UK

- by David Toy

Is there a service that provides latitude and longitude for UK phone numbers? For example: Query: 0141 574 xxx, Returns: (55.8659829, -4.2602205) [Glasgow City Centre] Allow me to stress that I am not looking for a reverse-directory-enquires. I am more interested in 'local area' for things like weather by phone or "Where's my nearest Pizza Shop?" If this service doesn't exist your suggestions on how to implement it or where to get data from would also be incredibly useful. I am aware that Ofcom provides a list of area codes with a place name [1] suitable for geolocation, but I have my concerns about resolution. I see this as a particular problem in smaller towns and rural areas where an area code will cover a large geographical area. Second Example: Area Code: 01555, Ofcom: Lanark However: 01555 860xxx is Crossford (4 miles W of Lanark) 01555 77xxxx is Carluke (5 miles NW) 01555 89xxxx is Lesmahagow (5 miles SW) 01555 840xxx is Carnwath (7 miles NE) Therefore 01555 covers about ~80 sq miles. That's not particularly local. [1] Ofcom Area Code Tool: http://www.ofcom.org.uk/consumer/2009/09/telephone-area-codes-tool/

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Binary search in a sorted (memory-mapped ?) file in Java

- by sds

I am struggling to port a Perl program to Java, and learning Java as I go. A central component of the original program is a Perl module that does string prefix lookups in a +500 GB sorted text file using binary search (essentially, "seek" to a byte offset in the middle of the file, backtrack to nearest newline, compare line prefix with the search string, "seek" to half/double that byte offset, repeat until found...) I have experimented with several database solutions but found that nothing beats this in sheer lookup speed with data sets of this size. Do you know of any existing Java library that implements such functionality? Failing that, could you point me to some idiomatic example code that does random access reads in text files? Alternatively, I am not familiar with the new (?) Java I/O libraries but would it be an option to memory-map the 500 GB text file (I'm on a 64-bit machine with memory to spare) and do binary search on the memory-mapped byte array? I would be very interested to hear any experiences you have to share about this and similar problems.

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Intelligent web features, algorithms (people you may follow, similar to you ...)

- by hilal

I have 3 main questions about the algorithms in intelligent web (web 2.0) Here the book I'm reading http://www.amazon.com/Algorithms-Intelligent-Web-Haralambos-Marmanis/dp/1933988665 and I want to learn the algorithms in deeper 1. People You may follow (Twitter) How can one determine the nearest result to my requests ? Data mining? which algorithms? 2. How you’re connected feature (Linkedin) Simply algorithm works like that. It draws the path between two nodes let say between Me and the other person is C. Me - A, B - A connections - C . It is not any brute force algorithms or any other like graph algorithms :) 3. Similar to you (Twitter, Facebook) This algorithms is similar to 1. Does it simply work the max(count) friend in common (facebook) or the max(count) follower in Twitter? or any other algorithms they implement? I think the second part is true because running the loop dict{count, person} for person in contacts: dict.add(count(common(person))) return dict(max) is a silly act in every refreshing page. 4. Did you mean (Google) I know that they may implement it with phonetic algorithm http://en.wikipedia.org/wiki/Phonetic_algorithm simply soundex http://en.wikipedia.org/wiki/Soundex and here is the Google VP of Engineering and CIO Douglas Merrill speak http://www.youtube.com/watch?v=syKY8CrHkck#t=22m03s What about first 3 questions? Any ideas are welcome ! Thanks

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Time complexity of a certain program

- by HokageSama

In a discussion with my friend i am not able to predict correct and tight time complexity of a program. Program is as below. /* This Function reads input array "input" and update array "output" in such a way that B[i] = index value of nearest greater value from A[i], A[i+1] ... A[n], for all i belongs to [1, n] Time Complexity: ?? **/ void createNearestRightSidedLargestArr(int* input, int size, int* output){ if(!input || size < 1) return; //last element of output will always be zero, since no element is present on its right. output[size-1] = -1; int curr = size - 2; int trav; while(curr >= 0){ if(input[curr] < input[curr + 1]){ output[curr] = curr + 1; curr--; continue; } trav = curr + 1; while( input[ output [trav] ] < input[curr] && output [trav] != -1) trav = output[trav]; output[curr--] = output[trav]; } } I said time complexity is O(n^2) but my friend insists that this is not correct. What is the actual time complexity?

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Calculating bounding grid coordinates to a user click on google maps/google earth

- by user170304

Hello, I have a requirement to calculate the centroid or geodesic midpoint of when a user clicks in between the lat/long grid crossing. The crossing forms a square in most parts of GE and sometimes elongated rectangles. This is due to the shape of the earth of course. I'm looking for a valid mathematical formula that would allow a user to click anywhere in between this grid and then an accurate function (in Javascript or server side code) that would take an assumed grid resolution (say 1km intervals for this discussion) and the input coordinates that should return a centroid coordinate within that graticule grid. To clarify please take a look at the attached image to my google group post: http://google-earth-api.googlegroups.com/web/Picture+5.png?gda=h5oFPz8AAAD315KpovipQeBwdfGpmW3ZhBc9PTADwYa-n193hZ6AItFmHuno63c7phcEXYVuRA6ccyFKn-rNKC-d1pM%5FIdV0&gsc=sz6bbAsAAABBKF7YXWYyc4GmXg-QruHj What I need to be able to do is if a user clicks anywhere in this grid square, I need to find the centroid or center point of that grid intersection/square or at least the bounding grid coordinates (that make the square). If we assume that the grid is UTM standard and has a max resolution of 1km (or make this a parameter), I need to detect the four other points nearby and then calculating the centroid is not as difficult. I welcome any feedback you all may have and appreciate it. I don't have a simple way of letting a user click anywhere on the grid and finding the grid bounding coordinates (making a square of 4 coordinates) or the centroid / midpoint of the graticule grid square necessary. One thought is to use assumptions as much as possible using a reference such as UTM coordinate reference. If I assume that the grid is X degrees wide, can we have a pure javascript function take any input coordinate and return for me the bounding graticule coordinates in Decimal Degrees? Another thought I had was to create the grid in a geo-spatial layer to take any input coordinate and return the nearest centroid of the graticule? Does this make sense? Thanks! Omar

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storing/retrieving data for graph with long continuous stretches

- by james

i have a large 2-dimensional data set which i would like to graph. the graph is displayed in a browser and the data is retrieved via ajax. long stretches of this graph will be continuous - e.g., for x=0 through x=1000, y=9, then for x=1001 through x=1100, y=80, etc. the approach i'm considering is to send (from the server) and store (in the browser) only the points where the data changes. so for the example above, i would say data[0] = 9, then data[1001] = 80. then given x=999 for example, retrieving data[999] would actually look up data[0]. the problem that arises is finding a dictionary-like data structure which behaves like this. the approach i'm considering is to store the data in a traditional dictionary object, then also maintain a sorted array of key for that object. when given x=999, it would look at the mid-point of this array, determine whether the nearest lower key is left or right of that midpoint, then repeat with the correct subsection, etc.. does anyone have thoughts on this problem/approach?

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deepcopy and python - tips to avoid using it?

- by blackkettle

Hi, I have a very simple python routine that involves cycling through a list of roughly 20,000 latitude,longitude coordinates and calculating the distance of each point to a reference point. def compute_nearest_points( lat, lon, nPoints=5 ): """Find the nearest N points, given the input coordinates.""" points = session.query(PointIndex).all() oldNearest = [] newNearest = [] for n in xrange(nPoints): oldNearest.append(PointDistance(None,None,None,99999.0,99999.0)) newNearest.append(obj2) #This is almost certainly an inappropriate use of deepcopy # but how SHOULD I be doing this?!?! for point in points: distance = compute_spherical_law_of_cosines( lat, lon, point.avg_lat, point.avg_lon ) k = 0 for p in oldNearest: if distance < p.distance: newNearest[k] = PointDistance( point.point, point.kana, point.english, point.avg_lat, point.avg_lon, distance=distance ) break else: newNearest[k] = deepcopy(oldNearest[k]) k += 1 for j in range(k,nPoints-1): newNearest[j+1] = deepcopy(oldNearest[j]) oldNearest = deepcopy(newNearest) #We're done, now print the result for point in oldNearest: print point.station, point.english, point.distance return I initially wrote this in C, using the exact same approach, and it works fine there, and is basically instantaneous for nPoints<=100. So I decided to port it to python because I wanted to use SqlAlchemy to do some other stuff. I first ported it without the deepcopy statements that now pepper the method, and this caused the results to be 'odd', or partially incorrect, because some of the points were just getting copied as references(I guess? I think?) -- but it was still pretty nearly as fast as the C version. Now with the deepcopy calls added, the routine does it's job correctly, but it has incurred an extreme performance penalty, and now takes several seconds to do the same job. This seems like a pretty common job, but I'm clearly not doing it the pythonic way. How should I be doing this so that I still get the correct results but don't have to include deepcopy everywhere?

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How to setup OpenGL camera for a racing game

- by vian

I need the view to show the road polygon (a rectangle 3.f * 100.f) with a vanishing point for a road being at 3/4 height of the viewport and the nearest road edge as a viewport's bottom side. See Crazy Taxi game for an example of what I wish to do. I'm using iPhone SDK 3.1.2 default OpenGL ES project template. I setup the projection matrix as follows: glMatrixMode(GL_PROJECTION); glLoadIdentity(); glFrustumf(-2.25f, 2.25f, -1.5f, 1.5f, 0.1f, 1000.0f); Then I use glRotatef to adjust for landscape mode and setup camera. glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glRotatef(-90, 0.0f, 0.0f, 1.0f); const float cameraAngle = 45.0f * M_PI / 180.0f; gluLookAt(0.0f, 2.0f, 0.0f, 0.0f, 0.0f, 100.0f, 0.0f, cos(cameraAngle), sin(cameraAngle)); My road polygon triangle strip is like this: static const GLfloat roadVertices[] = { -1.5f, 0.0f, 0.0f, 1.5f, 0.0f, 0.0f, -1.5f, 0.0f, 100.0f, 1.5f, 0.0f, 100.0f, }; And I can't seem to find the right parameters for gluLookAt. My vanishing point is always at the center of the screen.

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KD-Trees and missing values (vector comparison)

- by labratmatt

I have a system that stores vectors and allows a user to find the n most similar vectors to the user's query vector. That is, a user submits a vector (I call it a query vector) and my system spits out "here are the n most similar vectors." I generate the similar vectors using a KD-Tree and everything works well, but I want to do more. I want to present a list of the n most similar vectors even if the user doesn't submit a complete vector (a vector with missing values). That is, if a user submits a vector with three dimensions, I still want to find the n nearest vectors (stored vectors are of 11 dimensions) I have stored. I have a couple of obvious solutions, but I'm not sure either one seem very good: Create multiple KD-Trees each built using the most popular subset of dimensions a user will search for. That is, if a user submits a query vector of thee dimensions, x, y, z, I match that query to my already built KD-Tree which only contains vectors of three dimensions, x, y, z. Ignore KD-Trees when a user submits a query vector with missing values and compare the query vector to the vectors (stored in a table in a DB) one by one using something like a dot product. This has to be a common problem, any suggestions? Thanks for the help.

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How to map coordinates in AxesImage to coordinates in saved image file?

- by Vebjorn Ljosa

I use matplotlib to display a matrix of numbers as an image, attach labels along the axes, and save the plot to a PNG file. For the purpose of creating an HTML image map, I need to know the pixel coordinates in the PNG file for a region in the image being displayed by imshow. I have found an example of how to do this with a regular plot, but when I try to do the same with imshow, the mapping is not correct. Here is my code, which saves an image and attempts to print the pixel coordinates of the center of each square on the diagonal: import numpy as np import matplotlib.pyplot as plt fig = plt.figure() ax = fig.add_axes([0.1, 0.1, 0.8, 0.8]) axim = ax.imshow(np.random.random((27,27)), interpolation='nearest') for x, y in axim.get_transform().transform(zip(range(28), range(28))): print int(x), int(fig.get_figheight() * fig.get_dpi() - y) plt.savefig('foo.png', dpi=fig.get_dpi()) Here is the resulting foo.png, shown as a screenshot in order to include the rulers: The output of the script starts and ends as follows: 73 55 92 69 111 83 130 97 149 112 … 509 382 528 396 547 410 566 424 585 439 As you see, the y-coordinates are correct, but the x-coordinates are stretched: they range from 73 to 585 instead of the expected 135 to 506, and they are spaced 19 pixels o.c. instead of the expected 14. What am I doing wrong?

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Code Golf: Rotating Maze

- by trinithis

Code Golf: Rotating Maze Make a program that takes in a file consisting of a maze. The maze has walls given by '#'. The maze must include a single ball, given by a 'o' and any number of holes given by a '@'. The maze file can either be entered via command line or read in as a line through standard input. Please specify which in your solution. Your program then does the following: 1: If the ball is not directly above a wall, drop it down to the nearest wall. 2: If the ball passes through a hole during step 1, remove the ball. 3: Display the maze. 4: If there is no ball in the maze, exit. 5: Read a line from the standard input. Given a 1, rotate the maze counterclockwise. Given a 2, rotate the maze clockwise. Rotations are done by 90 degrees. It is up to you to decide if extraneous whitespace is allowed. If the user enters other inputs, repeat this step. 6: Goto step 1. You may assume all input mazes are closed. Note, a hole effectively acts as a wall in this regard. You may assume all input mazes have no extraneous whitespace. The shortest source code by character count wins. Example mazes: ###### #o @# ###### ########### #o # # ####### # ###@ # ######### ########################### # # # # @ # # # # ## # # ####o#### # # # # # # ######### # @ ######################

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Display image background fully for last repeat in a div

- by Stiggler

I have a 700x300 background repeating seamlessly under the main content-div. Now I'd like to attach a div at the bottom of the content-div, containing a continuation-to-end of the background image, connecting seamlessly with the background above it. Due to the nature of the pattern, unless the full 300px height of the background image is visible in the last repeat of the content-div's backround, the background in the div below won't seamlessly connect. Basically, I need the content div's height to be a multiple of 300px under all circumstances. What's a good approach to this sort of problem? I've tried resizing the content-div on loading the page, but this only works as long as the content div doesn't contain any resizing, dynamic content, which is not my case: function adjustContentHeight() { // Setting content div's height to nearest upper multiple of column backgrounds height, // forcing it not to be cut-off when repeated. var contentBgHeight = 300; var contentHeight = $("#content").height(); var adjustedHeight = Math.ceil(contentHeight / contentBgHeight); $("#content").height(adjustedHeight * contentBgHeight); } $(document).ready(adjustContentHeight); What I'm looking for there is a way to respond to a div resizing event, but there doesn't seem to be such a thing. Also, please assume I have no access to the JS controlling the resizing of content in the content-div, though this is potentially a way of solving the problem. Another potential solution I was thinking off was to offset the background image in the bottom div by a certain amount depending on the height of the content-div. Again, the missing piece seems to be the ability to respond to a resize event.

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How would i go about showing the closest paragraph element to a unique link with jQuery?

- by Nike

The title is a bit rusty, sorry about that. Now let me explain what i'm trying to do. I have a few listed items, like this: <li> <a id="toggle" class="0"><h4>ämne<small>2010-04-17 kl 12:54</small></h4></a> <p id="meddel" class="0">text</p> </li> <li class='odd'> <a id="toggle" class="1"><h4>test<small>2010-04-17 kl 15:01</small></h4></a> <p id="meddel" class="1">test meddelande :) [a]http://youtube.com[/a]</p> </li> The function i'm trying to achieve, is that when a user clicks a "toggle" link (the h4 text), i want the paragraph element below it to fade in. I thought of the idea of giving both the toggle link and the paragraph the same class, and then somehow make it get the paragraph with the same class as the toggle link clicked, and show it? But i'm not entirely sure how to do that either, and tbh, it doesn't sound like the greatest idea, but maybe that's the only way? I don't know... Is there some way to just simply get the nearest paragraph (below the link) with the id "meddel" and fade it in? That sounds a bit easier... I hope you can at least give me a few hints. Thanks in advance, -Nike

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NHibernate complex order query

- by manu08

Here's my simplified domain public class Notification { public Guid ID { get; set; } public string Name { get; set; } public IEnumerable<Location> Locations { get; set; } } public class Location { public Guid Id { get; set; } public string Name { get; set; } public decimal Longitude { get; set; } public decimal Latitude { get; set; } } Notifications and Locations have a many-to-many relationship (defined in table LocationsOnNotification). What I'd like to do is query for the nearest 10 Notifications from a given longitude and latitude. I've been trying to use ICriteria, but I'm not sure how to specify the ordering correctly: return Session.CreateCriteria<Notification>() .SetFirstResult(firstIndex) .SetMaxResults(maxResults) .AddOrder(Order.Asc( WHAT GOES HERE! )) .List<Notification>(); What I've been thinking of so far is adding a formula property to the Location mapping; something like this: <property name='Distance' formula='lots of geometry'/> But I'm not sure if that can take in parameters (since I'd need to pass in the user's location to calculate the distance), plus I'm not sure how to specify it in the Order.Asc clause given that it's a property on a many-to-many association class. Any ideas? Or perhaps I should take a different approach altogether. Thanks in advance!

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Javascript functions Math.round(num) vs num.toFixed(0) and browser inconsistencies

- by eft

Edit: To clarify, the problem is how to round a number to the nearest integer. i.e. 0.5 should round to 1 and 2.5 shoud round to 3. Consider the following code: <html><head></head><body style="font-family:courier"> <script> for (var i=0;i<3;i++){ var num = i + 0.50; var output = num + " " + Math.round(num) + " " + num.toFixed(0); var node = document.createTextNode(output); var pElement = document.createElement("p"); pElement.appendChild(node); document.body.appendChild(pElement); } </script> </body></html> In Opera 9.63 I get: 0.5 1 0 1.5 2 2 2.5 3 2 In FF 3.03 I get: 0.5 1 1 1.5 2 2 2.5 3 3 In IE 7 I get: 0.5 1 0 1.5 2 2 2.5 3 3 Note the bolded results. Does this mean that toFixed(0) should be avoided?

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How to create an AST with ANTLR from a hierarchical key-value syntax

- by Brabster

I've been looking at parsing a key-value data format with ANTLR. Pretty straightforward, but the keys represent a hierarchy. A simplified example of my input syntax: /a/b/c=2 /a/b/d/e=3 /a/b/d/f=4 In my mind, this represents a tree structured as follows: (a (b (= c 2) (d (= e 3) (= f 4)))) The nearest I can get is to use the following grammar: /* Parser Rules */ start: (component NEWLINE?)* EOF -> (component)*; component: FORWARD_SLASH ALPHA_STRING component -> ^(ALPHA_STRING component) | FORWARD_SLASH ALPHA_STRING EQUALS value -> ^(EQUALS ALPHA_STRING value); value: ALPHA_STRING; /* Lexer Rules */ NEWLINE : '\r'? '\n'; ALPHA_STRING : ('a'..'z'|'A'..'Z'|'0'..'9')+; EQUALS : '='; FORWARD_SLASH : '/'; Which produces: (a (b (= c 2))) (a (b (d (= e 3)))) (a (b (d (= f 4)))) I'm not sure whether I'm asking too much from a generic tool such as ANTLR here, and this is as close I can get with this approach. That is, from here I consume the parts of the tree and create the data structure I want by hand. So - can I produce the tree structure I want directly from a grammar? If so, how? If not, why not - is it a technical limitation in ANTLR or is it something more CS-y to do with the type of language involved?

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NHibernate correct way to reattach cached entity to different session

- by Chris Marisic

I'm using NHibernate to query a list of objects from my database. After I get the list of objects over them I iterate over the list of objects and apply a distance approximation algorithm to find the nearest object. I consider this function of getting the list of objects and apply the algorithm over them to be a heavy operation so I cache the object which I find from the algorithm in HttpRuntime.Cache. After this point whenever I'm given the supplied input again I can just directly pull the object from Cache instead of having to hit the database and traverse the list. My object is a complex object that has collections attached to it, inside the query where I return the full list of objects I don't bring back any of the sub collections eagerly so when I read my cached object I need lazy loading to work correctly to be able to display the object fully. Originally I tried using this to re-associate my cached object back to a new session _session.Lock(obj, LockMode.None); However when accessing the page concurrently from another instance I get the error Illegal attempt to associate a collection with two open sessions I then tried something different with _session.Merge(obj); However watching the output of this in NHProf shows that it is deleting and re-associating my object's contained collections with my object, which is not what I want although it seems to work fine. What is the correct way to do this? Neither of these seem to be right.

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Mapkit +closest annotation

- by danskcollignon

Hi all, I am trying to devellopp an app showing the nearest poi to the users location. My app is now capable of: showing a map (Mapkit) with 110 annotations and the user's location. Furthermore, I have a TableView at the bottom of my screen, to choose between the different annotations. However, they're listed by number, and not by proximity to the user's location, which is my wish. My research have led me to think that I should use CLLocation for getting the user's location. I then have really no idea on how to do it next, using getDistancefrom. My annotations are stored on SecondViewController.m, using this form: -(void)loadOurAnnotations { CLLocationCoordinate2D workingCoordinate; workingCoordinate.latitude = XX.XXXXX; workingCoordinate.longitude = XX.XXXXX; SecondViewAnnotation *POI1 = [[SecondViewAnnotation alloc] initWithCoordinate:workingCoordinate]; [POI1 setTitle:@"POI"]; [POI1 setSubtitle:@"StreetName"]; [POI1 setAnnotationType:SecondViewAnnotationTypePOI1]; [mapView addAnnotation:POI1]; , and so on to POI110. Could someone please give me a clue? I'm a total newbie! Thank you in advance for your help,

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Making a Javascript game, Having a little problem with scrolling.

- by RobertWHurst

I have a #wrapper div and a #grid div nested inside. currently I can scroll around with this function below. getCursorPos : function(){ // set the empty cursor object var cursor = {}; //get the offset from the left of the grid container var grid //offset loop $(function getCursorPos(){ grid = $('#grid').offset(); setTimeout(getCursorPos, game.loopSpeed); }); //continuosly get the position var that = this; $(document).mousemove(function(e){ //if game mode is menu exit if(game.mode === 'menu'){ return; } // NOTE: this looks a litle over done but don't remove anything // its like this because javascript uses floating points // and so in order to line up to the nearest hunderedth I // had to make the cursor and div position intergers by // muliplying by ten. one the two are added I reduced them // and rounded them. that.x = Math.round(((e.pageX * 10) - (grid.left * 10)) / 10); that.y = Math.round(((e.pageY * 10) - (grid.top * 10)) / 10); }); }, the problem is that the mouse coordinates only update when the mouse moves. is there any way to get the coordinates with out moving the mouse?

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How can I cluster short messages [Tweets] based on topic ? [Topic Based Clustering]

- by Jagira

Hello, I am planning an application which will make clusters of short messages/tweets based on topics. The number of topics will be limited like Sports [ NBA, NFL, Cricket, Soccer ], Entertainment [ movies, music ] and so on... I can think of two approaches to this Ask for users to tag questions like Stackoverflow does. Users can select tags from a predefined list of tags. Then on server side I will cluster them on based of tags. Pros:- Simple design. Less complexity in code. Cons:- Choices for users will be restricted. Clusters will not be dynamic. If a new event occurs, the predefined tags will miss it. Take the message, delete the stopwords [ predefined in a dictionary ] and apply some clustering algorithm to make a cluster and depending on its popularity, display the cluster. The cluster will be maintained according to its sustained popularity. New messages will be skimmed and assigned to corresponding clusters. Pros:- Dynamic clustering based on the popularity of the event/accident. Cons:- Increased complexity. More server resources required. I would like to know whether there are any other approaches to this problem. Or are there any ways of improving the above mentioned methods? Also suggest some good clustering algorithms.I think "K-Nearest Clustering" algorithm is apt for this situation.

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Glitch when moving camera in OpenGL

- by CG

I am writing a tile-based game engine for the iPhone and it works in general apart from the following glitch. Basically, the camera will always keep the player in the centre of the screen, and it moves to follow the player correctly and draws everything correctly when stationary. However whilst the player is moving, the tiles of the surface the player is walking on glitch as shown: Compared to the stationary (correct): Does anyone have any idea why this could be? Thanks for the responses so far. Floating point error was my first thought also and I tried slightly increasing the size of the tiles but this did not help. Changing glClearColor to red still leaves black gaps so maybe it isn't floating point error. Since the tiles in general will use different textures, I don't know if vertex arrays can be used (I always thought that the same texture had to be applied to everything in the array, correct me if I'm wrong), and I don't think VBO is available in OpenGL ES. Setting the filtering to nearest neighbour improved things but the glitch still happens every ten frames or so, and the pixelly result means that this solution is not viable anyway. The main difference between what I'm doing now and what I've done in the past is that this time I am moving the camera rather than the stationary objects in the world (i.e. the tiles, the player is still being moved). The code I'm using to move the camera is: void Camera::CentreAtPoint( GLfloat x, GLfloat y ) { glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrthof(x - size.x / 2.0f, x + size.x / 2.0f, y + size.y / 2.0f, y - size.y / 2.0f, 0.01f, 5.0f); glMatrixMode(GL_MODELVIEW); } Is there a problem with doing things this way and if so is there a solution?

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how to get selected chracter position in JTextArea?

- by Reddy

Hi! Here is a challenging question! Let me first tell you my scenario how am i implementing a solution to a problem. I am reading a log file and displaying it on the JTextArea. Log file is cp037 character coded. I was reading each file as a byte stream or byte array from the log file & displaying it. Anyways, i managed to display the text properly in JTextArea by cp037 character coding. Now, User may select a set of characters in the JTextArea. All i want is the position of first character of the user's selected text, from a nearest special character '+'(its character code in cp037 is 4E), which is prior to the selected text. This character may occur at several places in the JTextArea. In simple sentence, i want the first character location(of user selected text) from nearset '+' which should be occuring prior to the user's selected text. PS: cp037 is a type of character encoding scheme which is created by IBM & used for IBM Mainframes. Please fell free to ask me if the question is not clear...:-

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Can FFT length affect filtering accuracy?

- by Charles

Hi, I am designing a fractional delay filter, and my lagrange coefficient of order 5 h(n) have 6 taps in time domain. I have tested to convolute the h(n) with x(n) which is 5000 sampled signal using matlab, and the result seems ok. When I tried to use FFT and IFFT method, the output is totally wrong. Actually my FFT is computed with 8192 data in frequency domain, which is the nearest power of 2 for 5000 signal sample. For the IFFT portion, I convert back the 8192 frequency domain data back to 5000 length data in time domain. So, the problem is, why this thing works in convolution, but not in FFT multiplication. Does converting my 6 taps h(n) to 8192 taps in frequency domain causes this problem? Actually I have tried using overlap-save method, which perform the FFT and multiplication with smaller chunks of x(n) and doing it 5 times separately. The result seems slight better than the previous, and at least I can see the waveform pattern, but still slightly distorted. So, any idea where goes wrong, and what is the solution. Thank you.

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