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Search found 321 results on 13 pages for 'intersection'.

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• What is an Efficient algorithm to find Area of Overlapping Rectangles

  - by namenlos

  My situation Input: a set of rectangles each rect is comprised of 4 doubles like this: (x0,y0,x1,y1) they are not "rotated" at any angle, all they are "normal" rectangles that go "up/down" and "left/right" with respect to the screen they are randomly placed - they may be touching at the edges, overlapping , or not have any contact I will have several hundred rectangles this is implemented in C# I need to find The area that is formed by their overlap - all the area in the canvas that more than one rectangle "covers" (for example with two rectangles, it would be the intersection) I don't need the geometry of the overlap - just the area (example: 4 sq inches) Overlaps shouldn't be counted multiple times - so for example imagine 3 rects that have the same size and position - they are right on top of each other - this area should be counted once (not three times) Example The image below contains thre rectangles: A,B,C A and B overlap (as indicated by dashes) B and C overlap (as indicated by dashes) What I am looking for is the area where the dashes are shown - AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAA--------------BBB AAAAAAAAAAAAAAAA--------------BBB AAAAAAAAAAAAAAAA--------------BBB AAAAAAAAAAAAAAAA--------------BBB BBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBB BBBBBB-----------CCCCCCCC BBBBBB-----------CCCCCCCC BBBBBB-----------CCCCCCCC CCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCC

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• Simple way to implement computer-go board in Java

  - by codingbear

  I want to make a simple Go board to design an Computer Go game. In a go game, you lie a "stone" (white or black) on a position where horizontal and vertical lines intersect. What are some simple ways to restrict users from placing their stones in other locations? Maybe I'm just not seeing a simple solution. EDIT I guess I should rephrase my question better: I want to know how to do the background image of Go board, so that I can lie my stones on the intersection of the horizontal and the vertical lines. I was thinking about getting a just regular Go board image, and when I'm actually rendering stones, I find right position of pixels to lie stones. However, that solution did not seem to be the best solution, since I need to worry about size of stone images and think about proportionality when I either expand or shrink the board window.

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• How do i translate movement on the Canvas3D to movement in the virtual 3D world

  - by Coder

  My goal is to move a shape in the virtual world in such a way so that it ends up where the mouse pointer is on the canvas. What i have: -mouse position (x,y) on a Canvas3D object -Point3d object of where a pick ray starting from the Canvas3D viewport intersects with the first scene object. (point in 3D space of where i want to start the drag) What i want: -Some way to translate the Point3d's coordinates so that the initial point of intersection (the Point3d object) is always overlapping the the mouse position on the canvas (same as when i used the pick ray to determine what the user clicked on from the Canvas3D object). Thanks!

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• Add comma-separated value of grouped rows to existing query

  - by Peter Lang

  I've got a view for reports, that looks something like this: SELECT a.id, a.value1, a.value2, b.value1, /* (+50 more such columns)*/ FROM a JOIN b ON (b.id = a.b_id) JOIN c ON (c.id = b.c_id) LEFT JOIN d ON (d.id = b.d_id) LEFT JOIN e ON (e.id = d.e_id) /* (+10 more inner/left joins) */ It joins quite a few tables and returns lots of columns, but indexes are in place and performance is fine. Now I want to add another column to the result, showing comma-separated values ordered by value from table y outer joined via intersection table x if a.value3 IS NULL, else take a.value3 To comma-separate the grouped values I use Tom Kyte's stragg, could use COLLECT later. Pseudo-code for the SELECT would look like that: SELECT xx.id, COALESCE( a.value3, stragg( xx.val ) ) value3 FROM ( SELECT x.id, y.val FROM x WHERE x.a_id = a.id JOIN y ON ( y.id = x.y_id ) ORDER BY y.val ASC ) xx GROUP BY xx.id What is the best way to do it? Any tips?

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• Set Theory and .NET

  - by MasterMax1313

  Recently I came across a situation where set theory and set math fit what I was doing to the letter (granted there was an easier way to accomplish what I needed - i.e. LINQ - but I didn't think of that at the time). However I didn't know of any generic set libraries. Granted IEnumerables provide some set operations (Union, etc.), but nothing like Intersection or set comparison. Can anyone point out something that fits here? Something that implements set math using a generic type?

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• Confused by Perl grep function

  - by titaniumdecoy

  I don't understand the last line of this function from Programming Perl 3e. Here's how you might write a function that does a kind of set intersection by returning a list of keys occurring in all the hashes passed to it: @common = inter( \%foo, \%bar, \%joe ); sub inter { my %seen; for my $href (@_) { while (my $k = each %$href) { $seen{$k}++; } } return grep { $seen{$_} == @_ } keys %seen; } I understand that %seen is a hash which maps each key to the number of times it was encountered in any of the hashes provided to the function.

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• Implementing full text search on iPhone?

  - by Nimrod

  I'm looking for suggestions on the best way to implement a full-text search on some static data on the iPhone. Basically I have an app that contains the offline version of a web site, about 50MB of text, and I'd like for users to be able to search for terms. I figure that I should somehow build an table of ("word", reference_to_file_containing_word) or something, put that into either Core Data or just sqlite, index the "word" column, then have the search facility search the table for search terms and take the intersection of the sets of results for the terms or something. That wouldn't allow people to search for phrases but it would be pretty easy and probably not too slow. I'd like to just use existing SDK features for this. Should I use Core Data or sqlite? Does anyone have any other ideas on how this could be done?

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• Adding an element to a list in Scheme

  - by user272483

  I'm using R5RS Scheme and I just want to implement a function that returns the intersection of two given lists, but I can't do that because I cannot add an element to a list. Here is my code. How can I fix it? I'm really a beginner in Scheme - this is my first work using Scheme. thx in advance.. (define list3 '()) (define (E7 list1 list2) (cond ((null? list1) list3) ((member (car list1) list2) (append list3 (list (car list1)))) ) (cond ((null? list1) list3) ((not(null? list1)) (E7 (cdr list1) list2) ) ) ) (E7 '(4 5) '(3 4))

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• Coordinate geometry operations in images/discrete space

  - by avd

  I have images which have line segments, rays etc. I am representing these line segments using Bresenham algorithm (means whatever coordinates I get using this algorithm between two points). Now I want to do operations such as finding intersection point between two line segments, finding the projection of one vector onto other etc... The problem is I am not working in continuous space. The line segments are being approximated using Bresenham algorithm. So I want suggestions on what are the best and most efficient ways to do this? A link to C++ library or implementation would also be good enough. Please suggest some books which deal with such problems.

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• graphviz dot: how to insert arrows from a node to center of an arrow

  - by gregor

  Hi everyone, I try to create diagrams for MPLUS analyses with dot from the graphviz package. Does anybody have experience with using dot to visualize structural equation models/latent class mixture models? There is especially one feature that I can't figure out how to do beautifully: I need arrows from nodes to the center of another arrow like C | | V A ------------> B I tried to insert an invisible node at the intersection of the arrows. This, however, results in a "cracked" A---B arrow because dot does represent it as two independent arrows. Is this even possible with dot? Thanks for suggestions and help! Gregor

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• Should we use NsMutableArray in CGRectIntersect ?

  - by srikanth rongali

  To know whether two sprites cross each other or not, should we use NSMutableArray to store the sprites ? In my game one fixed sprite(player) is there. And the other is a bullet fired and if this sprite intersects player sprite, then enemy won. I have used NSMutable Array to store the bullet sprites. If I do not use NSMutableArray then even though the the bullet intersects player it is not recognizing the intersection ? I am using ( (CGRectIntersectsRect(bulletRect, playerRect)). Thank You.

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• An algorithm Problem

  - by Vignesh

  For coverage, I've a set of run time variables of from my program execution. It happens that I get it from a series of executions(Automated testing). ie. its a vector<vector<var,value>> I've a limited set of variables with expected values and generate combination s, that is I have vector<vector<var,value>(smaller than the execution vector)>. Now I need to compare and tell which of the combination I generated were exactly executed in one of the tests. My algo is O(n^4). Is there any way to bring it down. Something like set intersection. I'm using java, and vectors because of thread safety.

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• How to randomize a sorted list?

  - by Faken

  Here's a strange question for you guys, I have a nice sorted list that I wish to randomize. How would i go about doing that? In my application, i have a function that returns a list of points that describe the outline of a discretized object. Due to the way the problem is solved, the function returns a nice ordered list. i have a second boundary described in math and want to determine if the two objects intersect each other. I simply itterate over the points and determine if any one point is inside the mathematical boundary. The method works well but i want to increase speed by randomizing the point data. Since it is likely that that my mathematical boundary will be overlapped by a series of points that are right beside each other, i think it would make sense to check a randomized list rather than iterating over a nice sorted one (as it only takes a single hit to declare an intersection). So, any ideas on how i would go about randomizing an ordered list?

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• adding an element to a list in lisp

  - by user272483

  i'm using r5rs and i just want to implement a function that returns the intersection of two given lists but i can't do that because i can npot add element to a list. here is my code. how can i fix it? i'm really a beginner in lisp, this is my first work on lisp? thx in advance.. (define list3 '()) (define (E7 list1 list2) (cond ((null? list1) list3) ((member (car list1) list2) (append list3 (list (car list1)))) ) (cond ((null? list1) list3) ((not(null? list1)) (E7 (cdr list1) list2) ) ) ) (E7 '(4 5) '(3 4))

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• Date ranges intersections..

  - by Puzzled

  MS Sql 2008: I have 3 tables: meters, transformers (Ti) and voltage transformers (Tu) ParentId MeterId BegDate EndDate 10 100 '20050101' '20060101' ParentId TiId BegDate EndDate 10 210 '20050201' '20050501' 10 220 '20050801' '20051001' ParentId TuId BegDate EndDate 10 300 '20050801' '20050901' where date format is yyyyMMdd (year-month-day) Is there any way to get periods intersection and return the table like this? ParentId BegDate EndDate MeterId TiId TuId 10 '20050101' '20050201' 100 null null 10 '20050201' '20050501' 100 210 null 10 '20050501' '20050801' 100 null null 10 '20050801' '20050901' 100 220 300 10 '20050901' '20051001' 100 220 null 10 '20051001' '20060101' 100 null null Here is the table creation script: --meters declare @meters table (ParentId int, MeterId int, BegDate smalldatetime, EndDate smalldatetime ) insert @meters select 10, 100, '20050101', '20060101' --transformers declare @ti table (ParentId int, TiId int, BegDate smalldatetime, EndDate smalldatetime ) insert @ti select 10, 210, '20050201', '20050501' union all select 10, 220, '20050801', '20051001' --voltage transformers declare @tu table (ParentId int, TuId int, BegDate smalldatetime, EndDate smalldatetime ) insert @tu select 10, 300, '20050801', '20050901'

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• construct graph from python set type.

  - by Vincent

  The sort question, is the an off the self function to make a graph from a set of python sets? The longer: I have several python set types. They each overlap or some are sub sets of others. I would like to make a graph (as in nodes and edges) with the edges weighted by common intersection of the sets. There are several graphing packages for python. (NetworkX, igraph,...) I am not familiar with the use of any of them. Will any of them make a graph directly from a list of sets ie, MakeGraphfromSets(alistofsets) If not do you know of an example of how to take the list of sets to define the edges. It actually looks like it might be straight forward but an example is always good to have.

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• How does this Perl grep work to determine the union of several hashes?

  - by titaniumdecoy

  I don't understand the last line of this function from Programming Perl 3e. Here's how you might write a function that does a kind of set intersection by returning a list of keys occurring in all the hashes passed to it: @common = inter( \%foo, \%bar, \%joe ); sub inter { my %seen; for my $href (@_) { while (my $k = each %$href) { $seen{$k}++; } } return grep { $seen{$_} == @_ } keys %seen; } I understand that %seen is a hash which maps each key to the number of times it was encountered in any of the hashes provided to the function.

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• Confusing Perl code

  - by titaniumdecoy

  I don't understand the last line of this function from Programming Perl 3e. Here's how you might write a function that does a kind of set intersection by returning a list of keys occurring in all the hashes passed to it: @common = inter( \%foo, \%bar, \%joe ); sub inter { my %seen; for my $href (@_) { while (my $k = each %$href) { $seen{$k}++; } } return grep { $seen{$_} == @_ } keys %seen; } I understand that %seen is a hash which maps each key to the number of times it was encountered in any of the hashes provided to the function.

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• Alternative to 'where col in (list)' for MySQL

  - by user210481

  Hi I have the following table T: id 1 2 3 4 col a b a c I want to do a select that returns the id,col when group by(col) having count(col)1 One way of doing it is SELECT id,col FROM T WHERE col IN (SELECT col FROM T GROUP BY(col) HAVING COUNT(col)>1); The intern select (from the right) returns 'a' and main one (left) will return 1,a and 3,a The problem is that the where in statement seems to be extremely slow. In my real case, the results from the internal select has many 'col's, something about 70000 and it's taking hours. Right now it's much faster to do the internal select and the main select getting all ids and upcs and do the intersection locally. MySQL should be able to handle this kind of query efficiently. Can I substitute the where in for a join or something faster? Thanks

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• Tag Suggestion system, approaches and ideas

  - by Galois

  Hi guys! -- I am working on a (auto) tag suggestion system (NOT tag autocomplete). Lets say I want to suggest tags for a given question like here on SO (although SO's tagging system is auto-complete). My main idea is to get the intersection between the tags_set and the given question.split()_set. (In python the set_intersection is efficient enough). Also, in order to make it a little bit more accurate I might use words-distance to count as 'the same' very close words i.e movie == movies. For now I am not thinking about using any Collaborative Filtering technique looking for the tags to similar questions and so on, because I believe since the question text is pretty short (comparing with a blog article or a paper) it is not worth the effort. So I was wondering if you have any other (more) efficient approaches to suggest. Any ideas, specially from people who they have done something like that before, are more than welcome.

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• n*n blocks and polygons

  - by OSaad

  Hi, this is actually meant to be for a function called roipoly in matlab but it can be considered a general case problem. Roipoly is a function which lets u select a polygon over an image, and returns a binary mask where u can use it to get indices of the desired polygon. (It is just a normal polygon after all). My application (K-Nearest Neighbor) requires that i make n*n blocks out of the data i have (the polygon), i.e. If i have a polygon (a road or a piece of land), i want a n*n square moving over it while avoiding intersection with edges and putting those n*n pixels into some variable. This problem would be a lot easier if i had all my shapes in the form of rectangles, but that unfortunately isn't the case. I might have something going diagonal, circular or just irregular.

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• Interpolating height for a point inside a grid based on a discrete height function.

  - by fastrack20

  Hi, I have been wracking my brain to come up with a solution to this problem. I have a lookup table that returns height values for various points (x,z) on the grid. For instance I can calculate the height at A, B, C and D in Figure 1. However, I am looking for a way to interpolate the height at P (which has a known (x,z)). The lookup table only has values at the grid intervals, and P lies between these intervals. I am trying to calculate values s and t such that: A'(s) = A + s(C-A) B'(t) = B + t(P-B) I would then use the these two equations to find the intersection point of B'(t) with A'(s) to find a point X on the line A-C. With this I can calculate the height at this point X and with that the height at point P. My issue lies in calculating the values for s and t. Any help would be greatly appreciated.

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• In a graph, how to find the nearest node to a group of nodes?

  - by Nikola

  Hello, I have an undirected, unweighted graph, which doesn't have to be planar. I also have a subset of graph's nodes (true subset) and I need to find a node not belonging to the subset, with minimum sum of distances to all nodes in the subset. So far, I have implemented breath-first search starting from each node in the subset, and the intersection that occurs first is the node I am looking for. Unfortunately, it is running too slow since the graph contains a large number of nodes. Any advice or comment will be appreciated. Thank you, Nikola

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• Can't get flat QToolButton with border on hover stylesheet

  - by Max

  Hi, all! I need to implement textbox with inplace button (for search or filter purposes). So, I need to get Qtoolbutton, that is flat and rendered as icon, and obtain the border when hovered by mouse or pressed. And maybe I'd add some almost transparent background on hover too. I tried to set the following stylesheet: 'border: none; hover {border: 1px} pressed {border: 1px}' , but it seems that only border set. I tried to set autoRaise() to True and False, I mean, maybe some intersection occured, but haven't succeed.

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• Grammatically correct double-noun identifiers, plural versions

  - by Michal Czardybon

  Consider compounds of two nouns, which in natural English would most often appear in the form "noun of noun", e.g. "direction of light", "output of a filter". When programming we usually write "LightDirection" and "FilterOutput". Now, I have a problem with plural nouns. There are two cases: 1) singular of plural e.g. "union of (two) sets", "intersection of (two) segments" Which is correct, SetUnion and SegmentIntersection or SetsUnion and SegmentsIntersection? 2) plural of plural There are two subcases: (a) Many elements, each having many related elements, e.g. "outputs of filters" (b) Many elements, each having single related element, e.g. "directions of vectors" Shell I use FilterOutputs and VectorDirections or FiltersOutputs and VectorsDirections? I suspect correct is the first version (FilterOutupts, VectorDirections), but I think it may lead to ambiguities, e.g. FilterOutputs - many outputs of a single filter or many outputs of many filters? LineSegmentProjections - projections of many segments or many projections of a single segment?

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