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• How do you crop a specific area with paperclip in Rails (3)?

  - by Smickie

  Hi, I have paperclip in Rails (3) working with simple cropping, for example the blow code makes a simple crop of the thumbnail: has_attached_file :image, :styles => { :thumb => "90x90#" }, :default_style => :thumb However I was wondering how do you crop a very specific area of an image; lets say you have an x and y coordinate to start from and then a width and height of the crop. How do you go about passing a complex style like this in? Thanks very much.

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• Stored Procedure or calculations via IQueryable?

  - by Shawn Mclean

  This is a question that is based on choosing performance over design practices. If I have a method that will be executed many times a second; public static IQueryable<IPerson> InRadius(this IQueryable<IPerson> query, Coordinate center, double radius) { return (from u in query where CallHeavyMathFormula(u, center, radius) select u); } This extension method for IQueryable generates a SQL that does some heavy maths calculation (Cosine, Sine, etc). This would mean the application sends 1-2KB of sql to the server per call. I've heard of placing all application logic, in your application. I also would like to change to a database such as azure or one of those scalable databases in the future. How do I handle something like this? Should I leave it as it is now or write stored procedures? How do applications like twitter or facebook do it?

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• python win32 simulate click

  - by nabizan

  Let's say I've got a window for which I want to simulate a mouse click at a specific x, y coordinate. I already have the hwnd but I'm not sure how to construct the lParam. I've used SendMessage in the past to click on buttons, etc., but I knew their hwnds. Any help would be greatly appreciated. I also can't help but wonder if I'm going about this the right way. My end goal is clicking on a certain user on skype main window (for example). I used EnumChildWindows to find all the main window's children, but couldn't find the right one. So figured I would try to 'click' on it using coordinates.

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• What is an algorithm for minimizing some D distances between N items?

  - by Ross

  A classmate printed out a diagram of a database for class, the kind with lines representing relationships between tables. However, his lines crossed all over the place and it looked ugly. So I got to thinking about a way to move the tables to minimize the total line distance, and I couldn't think of a way to do it, other than just moving them all on top of each other. So basically: Given N items on some 2d coordinate space and some amount of connections between pairs of those items, how do you move the items so that the total distance between pairs is minimal, but that no distance is smaller than S? (so that the tables would not be too close together) Is there some algorithm for this? (I realize that smallest total distance won't necessarily make the layout less ugly; lines might still cross. But the table layout is just what got me thinking)

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• Simple graphics API with transparency, polygons, reading image pixels?

  - by M. Elkstein

  I need a simple graphics library that supports the following functionality: Ability to draw polygons (not just rectangles!) with RGBA colors (i.e., partially transparent), Ability to load bitmap images, Ability to read current color of pixel in a given coordinate. Ideally using JavaScript or Python. Seems like HTML 5 Canvas can handle #2 and #3 but not #1, whereas SVG can handle #1 and #2 but not #3. Am I missing something (about either of these two)? Or are there other alternatives?

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• What's the best way to implement one-dimensional collision detection?

  - by cyclotis04

  I'm writing a piece of simulation software, and need an efficient way to test for collisions along a line. The simulation is of a train crossing several switches on a track. When a wheel comes within N inches of the switch, the switch turns on, then turns off when the wheel leaves. Since all wheels are the same size, and all switches are the same size, I can represent them as a single coordinate X along the track. Switch distances and wheel distances don't change in relation to each other, once set. This is a fairly trivial problem when done through brute force by placing the X coordinates in lists, and traversing them, but I need a way to do so efficiently, because it needs to be extremely accurate, even when the train is moving at high speeds. There's a ton of tutorials on 2D collision detection, but I'm not sure the best way to go about this unique 1D scenario.

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• Connecting two DialogBoxes in GWT

  - by Apophenia Overload

  In my GWT project, I'm trying to get it so two DialogBoxes can pass information between each other. One of them holds a MapWidget, and when a button is pressed in the other DialogBox, the position information is received from that other DialogBox's MapWidget. Does anyone have any tips for how I should coordinate between having two different DialogBoxes show up? Should I wrap the code for the two in a Composite? Furthermore, is there an example anywhere of dealing with two DialogBoxes at once in GWT? For example, if I click outside of the two boxes, both should be dismissed. I'm wondering if there's a way to keep both of them in focus at once, so I can switch between the two without causing either to disappear.

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• How should I think about perspectives and rotation in OpenGL ES?

  - by Omega

  As I start to write rendering code, how do I want to consider my drawing operations? Will they always be relative to a fixed coordinate system on the screen, or does this change based on the camera perspective? The best example I can try to come up with is say I'm at (0,0,0) and I draw a line to (3,3,3). If I change the perspective +1 on the X axis and conduct the same operation, does it happen at (4,3,3), or am I just getting a new view of the line still being made at (3,3,3)? When doing rotation, am I moving the point from which a frustum emanates, or am I moving the rendering underneath?

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• preventing selection on MKPointAnnotation

  - by Derek

  Is there a way to prevent an annotation in a MKMapView instance from being enabled. In other words, when the user taps the red pin on the map, is there a way to prevent it from highlighting the pin. Right now the pin turns dark when touched... Edit: I'm using the following code to return the MKPinAnnotationView // To future MKMapView users - Don't forget to set _mapView's delegate _mapView.delegate = self; _annotation = [[MKPointAnnotation alloc] init]; _annotation.coordinate = myLocation; [_mapView addAnnotation:_annotation]; -(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation{ MKPinAnnotationView *pin = [[MKPinAnnotationView alloc] initWithAnnotation:_annotation reuseIdentifier:@"id"]; pin.enabled = NO; return pin; }

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• How to find patterns (lines, circles,...) from a list of points?

  - by Burkhard

  I have a list of points. Each point being an x and y coordinate (both of which are integers). Now I'm trying to find known patterns, such as lines, arcs or circles, knowing that the points are not perfectly on the pattern. What's the best way to do it? I don't have many clues to get started. Edit: the points are ordered. The user is drawing something and the program should detect the best patterns. For instance, if a triangle is drawn, it should detect three lines.

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• Math - Convert Arbitrary Length to Range From -1.0 to 1.0?

  - by TheDarkIn1978

  how can i convert a length into a range of -1.0 to 1.0? example: my stage is 440px in length and accepts mouse events. i would like to click in the middle of the stage, and rather than an output of X = 220, i'd like it to be X = 0. similarly, i'd like the real X = 0 to become X = -1.0 and the real X = 440 to become X = 1.0. i don't have access to the stage, so i can't simply center-register it, which would make this process a lot easier. also, it's not possible to dynamically change the actual size of my stage, so i'm looking for a formula that will translate the mouse's real X coordinate of the stage to evenly fit within a range from -1 to 1.

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• Reading Matrices in MATLAB and assigning coordinates to the entries

  - by Michael Schofield

  Hi, I'm a bit new to MATLAB. Basically, I have a 25x25 Matrix, complete with various random entries ranging from 0 to 3. I need to write a program that reads this matrix, and assigns x-y coordinates to the entries, so that when I ask for an input of a particular x-y coordinate which has, say an entry of 3, then it will result in an error. I'm a bit overwhelmed - but I understand the general concept of what I'm supposed to be finding. I'm wondering if I should use a plot instead to help me.

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• How can I take zooming into account when a user touches a UIScrollView?

  - by Bill

  I have a UIImageView inside of a UIScrollView. The parent scroll view allows zooming and panning. When the user taps a point in the scroll view, I want to find the location in the raw image inside the UIImageView - i.e. I want the point after including any zooming and panning the user has done in the scroll view. Right now, I have a UIScrollView subclass called ForwardingScrollView that handles touch events and attempts to convert them into locations in the coordinate system of the child image view. I tried adding contentOffset to these points, tried multiplying them by zoomScale, and even tried doing both. I also tried calling [touch locationInView: self] and [touch locationInView: parent], but none of these methods correctly return the point that I clicked in the underlying image. What's the best way to do this? Thanks in advance.

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• Database/NoSQL - Lowest latecy way to retreive the following data...

  - by Nickb

  I have a real estate application and a "house" contains the following information: house: - house_id - address - city - state - zip - price - sqft - bedrooms - bathrooms - geo_latitude - geo_longitude I need to perform an EXTREMELY fast (low latency) retrieval of all homes within a geo-coordinate box. Something like the SQL below (if I were to use a database): SELECT * from houses WHERE latitude IS BETWEEN xxx AND yyy AND longitude IS BETWEEN www AND zzz Question: What would be the quickest way for me to store this information so that I can perform the fastest retrieval of data based on latitude & longitude? (e.g. database, NoSQL, memcache, etc)?

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• Convert arbitrary length to a value between -1.0 a 1.0?

  - by TheDarkIn1978

  How can I convert a length into a value in the range -1.0 to 1.0? Example: my stage is 440px in length and accepts mouse events. I would like to click in the middle of the stage, and rather than an output of X = 220, I'd like it to be X = 0. Similarly, I'd like the real X = 0 to become X = -1.0 and the real X = 440 to become X = 1.0. I don't have access to the stage, so i can't simply center-register it, which would make this process a lot easier. Also, it's not possible to dynamically change the actual size of my stage, so I'm looking for a formula that will translate the mouse's real X coordinate of the stage to evenly fit within a range from -1 to 1.

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• Calculating the angle between two points

  - by kingrichard2005

  I'm currently developing a simple 2D game for Android. I have a stationary object that's situated in the center of the screen and I'm trying to get that object to rotate and point to the area on the screen that the user touches. I have the constant coordinates that represent the center of the screen and I can get the coordinates of the point that the user taps on. I'm using the formula outlined in this forum: How to get angle between two points? -It says as follows "If you want the the angle between the line defined by these two points and the horizontal axis: double angle = atan2(y2 - y1, x2 - x1) * 180 / PI;". -I implemented this, but I think the fact the I'm working in screen coordinates is causing a miscalculation, since the Y-coordinate is reversed. I'm not sure if this is the right way to go about it, any other thoughts or suggestions are appreciated.

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• Random walk- Brownian Motion

  - by Sam

  I've been assigned the project of creating a simple console app. that models brownian motion in a 2D plane. I wasn't given much information on how to do so (and I'm hoping that it's a pretty popular assignment so that I could get some insight) just that it relies on random number generation. I researched brownian motion for a little bit and saw some formulas that looked complicated, but by the description is just seems to have to move randomly within a certain number interval. Can anyone clarify? Am I to create a program that continually creates a random number in an interval and then modify the particles "x" and "y" coordinate or is there more to it? Thanks for any help.

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• Intersection between sets containing different types of variables

  - by Gacek

  Let's assume we have two collections: List<double> values List<SomePoint> points where SomePoint is a type containing three coordinates of the point: SomePoint { double X; double Y; double Z; } Now, I would like to perform the intersection between these two collections to find out for which points in points the z coordinate is eqal to one of the elements of values I created something like that: HashSet<double> hash = new HashSet<double>(points.Select(p=>p.Z)); hash.IntersectWith(values); var result = new List<SomePoints>(); foreach(var h in hash) result.Add(points.Find(p => p.Z == h)); But it won't return these points for which there is the same Z value, but different X and Y. Is there any better way to do it?

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• How to get left-top and right-buttom latitude and longitude of map in MapKit For iPad ?

  - by damniatx

  Hi, i'm looking for answer about getting latitude and longitude from uimapkit. there is same problem that has been answered, but it didn't give right coordinate. http://yit.me/3ddp73 it's code from thread i'm linking above. CLLocationCoordinate2D topLeft, bottomRight; topLeft = [mapView convertPoint:CGPointMake(0,0) toCoordinateFromView:mapView]; CGPoint pointBottomRight = CGPointMake(mapView.frame.size.width, mapView.frame.size.height); bottomRight = [mapView convertPoint:pointBottomRight toCoordinateFromView:mapView]; NSLog(@"topleft = %f", topLeft); NSLog(@"bottom right = %f", bottomRight); any idea to fix this issue ? thanks

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• MoveWindow API doesn't work well on Vista

  - by Dex Ilic

  Hello! I have an application on Vista which loops through all processes and finds associated main windows in order to move and resize them. The problem is that some windows get moved and resized and some don't. Also it even seems that moved and resized windows aren't moved and resized according to the MoveWindow function call because they are resized to title bar and all of them are on the same line (same y coordinate). Here's the sample code: IntPtr handle; Process[] processList = Process.GetProcesses(); int i = 0; foreach (Process process in processList) { handle = process.MainWindowHandle; if (handle != IntPtr.Zero) //If the process has window then move and resize it. { bool moveResult = MoveWindow(handle, i * 50, i * 50, 500, 500, true); i++; } } Is this because of Vista? What alternative should I use?

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• Normalized Device Coordinates to window coordinates

  - by okoman

  I just read some stuff about the theory behind 3d graphics. As I understand it, normalized device coordinates (NDC) are coordinates that describe a point in the interval from -1 to 1 on both the horizontal and vertical axis. On the other hand window coordinates describe a point somewhere between (0,0) and (width,height) of the window. So my formula to convert a point from the NDC coordinate system to the window system would be xwin = width + xndc * 0.5 * width ywin = height + ynfv * 0.5 * height The problem now is that in the OpenGL documentation for glViewport there is an other formula: xwin = ( xndc + 1 ) * width * 0.5 + x ywin = ( yndc + 1 ) * height * 0.5 + y Now I'm wondering what I am getting wrong. Especially I'm wondering what the additional "x" and "y" mean. Hope the question isn't too "not programming related", but I thought somehow it is related to graphics programming.

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• A 3-D grid of regularly spaced points

  - by Jack

  I want to create a list containing the 3-D coords of a grid of regularly spaced points, each as a 3-element tuple. I'm looking for advice on the most efficient way to do this. In C++ for instance, I simply loop over three nested loops, one for each coordinate. In Matlab, I would probably use the meshgrid function (which would do it in one command). I've read about meshgrid and mgrid in Python, and I've also read that using numpy's broadcasting rules is more efficient. It seems to me that using the zip function in combination with the numpy broadcast rules might be the most efficient way, but zip doesn't seem to be overloaded in numpy.

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• Jenkins to not allow the same job to run concurrently on the same node?

  - by Marek Gimza

  I have 4 nodes and 2 jobs. Any node can run 2 jobs concurrently and any job can be executed concurrently. I want to be able to restrict running the same job concurrently on the same machine. For example: Jobs: J1 and J2 nodes: N1,N2,N3 and N4 I can run J1 and J2 on the same node at the same time. I can run J1 on N1 and N3 at the same time. BUT I do not want to run J1 and another build of J1 on the same node at the same time. I have tried "Locks and Latches", "Jenkins Exclusive Execution", "Exclusion Plugin" plugins, and these will work well when trying to coordinate different jobs. But my case is trying to manage different build-instances of the same job.

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• Have anyone ever create/manipulate a table application from the ground up/scratch?

  - by Darwin

  Have anyone ever create/manipulate a table application from the ground up/scratch? I want to create a table using flash AS 3. I like to have the features like to the MS Studio Web Developer option. The options are create a table, merge cells, split cell, resize columns, delete cell, delete row, delete column etc... I think this is going to be very complicated thing to do. I think the only way to do it is to build it from the ground up because I don’t think Flash has the library/component for it. I was able to create rows and columns by creating the # of rectangles listed it from the left to the right and move the next coordinate for the next row. Now the most challenging this is to manipulate it. This is the must have feature on my website and we don’t want use Javascript to create table on the server side to create the table.

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• Matplotlib Contour Clabel Location

  - by jotimaz

  I would like to control the location of matplotlib clabels on a contour plot, but without utilizing the manual=True flag in clabel. For example, I would like to specify an x-coordinate, and have labels created at the points that pass through this line. I see that you can get the location of the individual labels using get_position(), but I am stuck at that. Any help would be greatly appreciated. Thanks! EDIT: The above image is an example plot that I would like to apply this method to. The default label positions are inconvenient -- the flat areas between Day 2 and Day 4 would be more visually appealing.

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