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  • How can I debug or set a break statement inside an expression tree?

    - by Abel
    When an external library contains a LINQ provider, and it throws an exception when executing a dynamic expression tree, how can I break when that expression is thrown? For example, I use a third party LINQ2CRM provider, which allows me to call the Max<TSource, TResult>() method of IQueryable, but when it throws an InvalidCastException, I fail to break on the spot when the exception is thrown, making it hard to review the stack-trace because it's already unwinded when the debugger breaks it in my code. I've set "break on throw" for the mentioned exception. My debug settings are: Clarification on where exactly I'd want to break. I do not want to break in side the LINQ Expression, but instead, I want to break when the expression tree is executed, or, put in other words, when the IQueryable extension method Max() calls the override provided by the LINQ provider. The top of the stacktrace looks like this, which is where I would like to break inside (or step through, or whatever): at XrmLinq.QueryProviderBase.Execute[T](Expression expression) at System.Linq.Queryable.Max[TSource,TResult](IQueryable`1 source, Expression`1 selector)

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  • Build a decision tree for classification of large amount data,using python?

    - by kaushik
    Hi,i am working for speech synthesis.In this i have a large number of pronunciation for each phone i.e alphabet and need to classify them according to few feature such as segment size(int) and alphabet itself(string) into a smaller set suitable for that particular context. For this purpose,i have decided to use decision tree for classification.the data to be parsed is in the S expression format.eg:((question)(LEFTNODE)(RIGHTNODE)). i hav idea for building decision tree for normal buit in type such as list..looking for suggestion for implementation for S expression.. kindly help.. Thanks in advance.. Note:this question may look similar to my prev post,srry if cant giv multiple post.already edited it many times so though of wirting new question instead of editing again

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  • Chess board position numbers in 6-rooted-binary tree?

    - by HH
    The maximum number of adjacent vertices is 6 that corresponds to the number of roots. By the term root, I mean the number of children for each node. If adjacent square is empty, fill it with Z-node. So every square will have 6 nodes. How can you formulate it with binary tree? Is the structure just 6-rooted-binary tree? What is the structure called if nodes change their positions? Suppose partially ordered list where its units store a large randomly expanding board. I want a self-adjusting data structure, where it is easy to calculate distances between nodes. What is its name?

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  • Can I ReRender the entire tree of a component?

    - by Ben
    Hi, I have a JSF application with several major components and a component tree under each. On a certain event (Value change) I would like to reRender the entire component tree for one of those components. For example: can I rerender components 1,2 and 3 in one shot here: <h:panelgroup id="1"> <h:panelgroup id="2"> <h:panelgroup id="3"> <h:panelgroup/> <h:panelgroup/> <h:panelgroup/> <h:commandButton rerender="1*"> <--- Made up code. Is that possible? Another Idea - Can I reRender with wildcards? (I.E - ReRender all components who's ID's begin or contain: "UpdateMe") Thanks!

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  • How do I manipulate a tree of immutable objects?

    - by Frederik
    I'm building an entire application out of immutable objects so that multi-threading and undo become easier to implement. I'm using the Google Collections Library which provides immutable versions of Map, List, and Set. My application model looks like a tree: Scene is a top-level object that contains a reference to a root Node. Each Node can contain child Nodes and Ports. An object graph might look like this: Scene | +-- Node | +-- Node | +- Port +-- Node | +- Port +- Port If all of these objects are immutable, controlled by a top-level SceneController object: What is the best way to construct this hierarchy? How would I replace an object that is arbitrarily deep in the object tree? Is there a way to support back-links, e.g. a Node having a "parent" attribute?

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  • Is Family Tree Maker 2011 the right upgrade for a FTM 11 user?

    - by bill weaver
    My father has used Family Tree Maker for years, but hasn't upgraded since version 11. It is difficult to tell from reviews at Amazon and other places whether upgrading to FTM 2011 is a good choice. File incompatibilities and upgrade woes sound like customer service is lacking, and i've read reports of it uploading your data to their database but then trying to sell you a download of data. Looking at the ancestry.com site makes me think it's solely about selling add-ons and upgrades. On the other hand, the feature set seems fairly rich and the software has a pretty strong following. I was able to get Gramps working on my system, but that's not going to work for my dad. Any advice on a good upgrade path?

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  • Copying a large directory tree locally? cp or rsync?

    - by Rory
    I have to copy a large directory tree, about 1.8 TB. It's all local. Out of habit I'd use rsync, however I wonder if there's much point, and if I should rather use cp. I'm worried about permissions and uid/gid, since they have to be preserved in the clopy (I know rsync does this). As well as thinks like symlinks. The destination is empty, so I don't have to worry about conditionally updating some files. It's all local disk access, so I don't have to worry about ssh or network. The reason I'd be tempted away from rsync, is because rsync might do more than I need. rsync checksums files. I don't need that, and am concerned that it might take longer than cp. So what do you reckon, rsync or cp?

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  • Windows 7 Explorer - Activate mouse focus to be able to scroll in tree and file view?

    - by none
    I'd like to be able to scroll in the tree view without having to click in it. Is there a way to do this? I have once used a tool that generally gives focus to the window underneath the mouse cursor, but this caused some other glitches so I would like to achieve this without an extra tool. I also think that there are programs that embed the Windows Explorer and offer more features, including the behaviour I would like to have. But maybe a registry value change is all that is needed?

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  • How can I store this kind of graph in neo4j for fast traversal?

    - by James
    This is a graph whose nodes exist in many connected components at once because a node's relationships are a collection of edge groups such that only one edge per edge group can be present at once. I need to be able to find all of the connected components that a node exists in. What would be the best way to store this graph in neo4j to quickly find all of the connected components that a node exists in? Is there a way to use the built in traversals to do this? Also: is there a name for this kind of graph? I'd appreciate any help/ideas. Update: Sorry for not being clear. All nodes are of the same type. Nodes have a variable number of edge groups. Exactly one edge from each edge group needs to be chosen for a particular connected component. I'm going to try to explain through example: Node x1 is related to: (x2 or x3 or x4) AND (x5 or x6) AND (x7) Node x2 is related to: (x8) AND (x9 or x10) So x1's first edge group is (x2, x3, x4), its second edge group is (x5, x6), and its third edge group is (x7). So here are a few connected components that x1 exists in: CC1: x1 is related to: x2, x5, x7 x2 is related to: x8 x9 CC2: x1 is related to: x2, x6, x7 x2 is related to: x8, x9 CC3: x1 is related to: x3, x5, x7 CC4: x1 is related to: x3, x6, x7 etc. I'm grateful for your help in this.

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  • Add collison detection to enemy sprites?

    - by xBroak
    i'd like to add the same collision detection used by the player sprite to the enemy sprites or 'creeps' ive added all the relevant code I can see yet collisons are still not being detected and handled, please find below the class, I have no idea what is wrong currently, the list of walls to collide with is 'wall_list' import pygame import pauseScreen as dm import re from pygame.sprite import Sprite from pygame import Rect, Color from random import randint, choice from vec2d import vec2d from simpleanimation import SimpleAnimation import displattxt black = (0,0,0) white = (255,255,255) blue = (0,0,255) green = (101,194,151) global currentEditTool currentEditTool = "Tree" global editMap editMap = False open('MapMaker.txt', 'w').close() def draw_background(screen, tile_img): screen.fill(black) img_rect = tile_img.get_rect() global rect rect = img_rect nrows = int(screen.get_height() / img_rect.height) + 1 ncols = int(screen.get_width() / img_rect.width) + 1 for y in range(nrows): for x in range(ncols): img_rect.topleft = (x * img_rect.width, y * img_rect.height) screen.blit(tile_img, img_rect) def changeTool(): if currentEditTool == "Tree": None elif currentEditTool == "Rock": None def pauseGame(): red = 255, 0, 0 green = 0,255, 0 blue = 0, 0,255 screen.fill(black) pygame.display.update() if editMap == False: choose = dm.dumbmenu(screen, [ 'Resume', 'Enable Map Editor', 'Quit Game'], 64,64,None,32,1.4,green,red) if choose == 0: print("hi") elif choose ==1: global editMap editMap = True elif choose ==2: print("bob") elif choose ==3: print("bob") elif choose ==4: print("bob") else: None else: choose = dm.dumbmenu(screen, [ 'Resume', 'Disable Map Editor', 'Quit Game'], 64,64,None,32,1.4,green,red) if choose == 0: print("Resume") elif choose ==1: print("Dis ME") global editMap editMap = False elif choose ==2: print("bob") elif choose ==3: print("bob") elif choose ==4: print("bob") else: None class Wall(pygame.sprite.Sprite): # Constructor function def __init__(self,x,y,width,height): pygame.sprite.Sprite.__init__(self) self.image = pygame.Surface([width, height]) self.image.fill(green) self.rect = self.image.get_rect() self.rect.y = y self.rect.x = x class insertTree(pygame.sprite.Sprite): def __init__(self,x,y,width,height, typ): pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load("images/map/tree.png").convert() self.image.set_colorkey(white) self.rect = self.image.get_rect() self.rect.y = y self.rect.x = x class insertRock(pygame.sprite.Sprite): def __init__(self,x,y,width,height, typ): pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load("images/map/rock.png").convert() self.image.set_colorkey(white) self.rect = self.image.get_rect() self.rect.y = y self.rect.x = x class Creep(pygame.sprite.Sprite): """ A creep sprite that bounces off walls and changes its direction from time to time. """ change_x=0 change_y=0 def __init__( self, screen, creep_image, explosion_images, field, init_position, init_direction, speed): """ Create a new Creep. screen: The screen on which the creep lives (must be a pygame Surface object, such as pygame.display) creep_image: Image (surface) object for the creep explosion_images: A list of image objects for the explosion animation. field: A Rect specifying the 'playing field' boundaries. The Creep will bounce off the 'walls' of this field. init_position: A vec2d or a pair specifying the initial position of the creep on the screen. init_direction: A vec2d or a pair specifying the initial direction of the creep. Must have an angle that is a multiple of 45 degres. speed: Creep speed, in pixels/millisecond (px/ms) """ Sprite.__init__(self) self.screen = screen self.speed = speed self.field = field self.rect = creep_image.get_rect() # base_image holds the original image, positioned to # angle 0. # image will be rotated. # self.base_image = creep_image self.image = self.base_image self.explosion_images = explosion_images # A vector specifying the creep's position on the screen # self.pos = vec2d(init_position) # The direction is a normalized vector # self.direction = vec2d(init_direction).normalized() self.state = Creep.ALIVE self.health = 15 def is_alive(self): return self.state in (Creep.ALIVE, Creep.EXPLODING) def changespeed(self,x,y): self.change_x+=x self.change_y+=y def update(self, time_passed, walls): """ Update the creep. time_passed: The time passed (in ms) since the previous update. """ if self.state == Creep.ALIVE: # Maybe it's time to change the direction ? # self._change_direction(time_passed) # Make the creep point in the correct direction. # Since our direction vector is in screen coordinates # (i.e. right bottom is 1, 1), and rotate() rotates # counter-clockwise, the angle must be inverted to # work correctly. # self.image = pygame.transform.rotate( self.base_image, -self.direction.angle) # Compute and apply the displacement to the position # vector. The displacement is a vector, having the angle # of self.direction (which is normalized to not affect # the magnitude of the displacement) # displacement = vec2d( self.direction.x * self.speed * time_passed, self.direction.y * self.speed * time_passed) self.pos += displacement # When the image is rotated, its size is changed. # We must take the size into account for detecting # collisions with the walls. # self.image_w, self.image_h = self.image.get_size() bounds_rect = self.field.inflate( -self.image_w, -self.image_h) if self.pos.x < bounds_rect.left: self.pos.x = bounds_rect.left self.direction.x *= -1 elif self.pos.x > bounds_rect.right: self.pos.x = bounds_rect.right self.direction.x *= -1 elif self.pos.y < bounds_rect.top: self.pos.y = bounds_rect.top self.direction.y *= -1 elif self.pos.y > bounds_rect.bottom: self.pos.y = bounds_rect.bottom self.direction.y *= -1 # collision detection old_x=bounds_rect.left new_x=old_x+self.direction.x bounds_rect.left = new_x # hit a wall? collide = pygame.sprite.spritecollide(self, walls, False) if collide: # yes bounds_rect.left=old_x old_y=self.pos.y new_y=old_y+self.direction.y self.pos.y = new_y collide = pygame.sprite.spritecollide(self, walls, False) if collide: # yes self.pos.y=old_y elif self.state == Creep.EXPLODING: if self.explode_animation.active: self.explode_animation.update(time_passed) else: self.state = Creep.DEAD self.kill() elif self.state == Creep.DEAD: pass #------------------ PRIVATE PARTS ------------------# # States the creep can be in. # # ALIVE: The creep is roaming around the screen # EXPLODING: # The creep is now exploding, just a moment before dying. # DEAD: The creep is dead and inactive # (ALIVE, EXPLODING, DEAD) = range(3) _counter = 0 def _change_direction(self, time_passed): """ Turn by 45 degrees in a random direction once per 0.4 to 0.5 seconds. """ self._counter += time_passed if self._counter > randint(400, 500): self.direction.rotate(45 * randint(-1, 1)) self._counter = 0 def _point_is_inside(self, point): """ Is the point (given as a vec2d) inside our creep's body? """ img_point = point - vec2d( int(self.pos.x - self.image_w / 2), int(self.pos.y - self.image_h / 2)) try: pix = self.image.get_at(img_point) return pix[3] > 0 except IndexError: return False def _decrease_health(self, n): """ Decrease my health by n (or to 0, if it's currently less than n) """ self.health = max(0, self.health - n) if self.health == 0: self._explode() def _explode(self): """ Starts the explosion animation that ends the Creep's life. """ self.state = Creep.EXPLODING pos = ( self.pos.x - self.explosion_images[0].get_width() / 2, self.pos.y - self.explosion_images[0].get_height() / 2) self.explode_animation = SimpleAnimation( self.screen, pos, self.explosion_images, 100, 300) global remainingCreeps remainingCreeps-=1 if remainingCreeps == 0: print("all dead") def draw(self): """ Blit the creep onto the screen that was provided in the constructor. """ if self.state == Creep.ALIVE: # The creep image is placed at self.pos. To allow for # smooth movement even when the creep rotates and the # image size changes, its placement is always # centered. # self.draw_rect = self.image.get_rect().move( self.pos.x - self.image_w / 2, self.pos.y - self.image_h / 2) self.screen.blit(self.image, self.draw_rect) # The health bar is 15x4 px. # health_bar_x = self.pos.x - 7 health_bar_y = self.pos.y - self.image_h / 2 - 6 self.screen.fill( Color('red'), (health_bar_x, health_bar_y, 15, 4)) self.screen.fill( Color('green'), ( health_bar_x, health_bar_y, self.health, 4)) elif self.state == Creep.EXPLODING: self.explode_animation.draw() elif self.state == Creep.DEAD: pass def mouse_click_event(self, pos): """ The mouse was clicked in pos. """ if self._point_is_inside(vec2d(pos)): self._decrease_health(3) #begin new player class Player(pygame.sprite.Sprite): change_x=0 change_y=0 frame = 0 def __init__(self,x,y): pygame.sprite.Sprite.__init__(self) # LOAD PLATER IMAGES # Set height, width self.images = [] for i in range(1,17): img = pygame.image.load("images/player/" + str(i)+".png").convert() #player images img.set_colorkey(white) self.images.append(img) self.image = self.images[0] self.rect = self.image.get_rect() self.rect.y = y self.rect.x = x self.health = 15 self.image_w, self.image_h = self.image.get_size() health_bar_x = self.rect.x - 7 health_bar_y = self.rect.y - self.image_h / 2 - 6 screen.fill( Color('red'), (health_bar_x, health_bar_y, 15, 4)) screen.fill( Color('green'), ( health_bar_x, health_bar_y, self.health, 4)) def changespeed(self,x,y): self.change_x+=x self.change_y+=y def _decrease_health(self, n): """ Decrease my health by n (or to 0, if it's currently less than n) """ self.health = max(0, self.health - n) if self.health == 0: self._explode() def update(self,walls): # collision detection old_x=self.rect.x new_x=old_x+self.change_x self.rect.x = new_x # hit a wall? collide = pygame.sprite.spritecollide(self, walls, False) if collide: # yes self.rect.x=old_x old_y=self.rect.y new_y=old_y+self.change_y self.rect.y = new_y collide = pygame.sprite.spritecollide(self, walls, False) if collide: # yes self.rect.y=old_y # right to left if self.change_x < 0: self.frame += 1 if self.frame > 3*4: self.frame = 0 # Grab the image, divide by 4 # every 4 frames. self.image = self.images[self.frame//4] # Move left to right. # images 4...7 instead of 0...3. if self.change_x > 0: self.frame += 1 if self.frame > 3*4: self.frame = 0 self.image = self.images[self.frame//4+4] if self.change_y > 0: self.frame += 1 if self.frame > 3*4: self.frame = 0 self.image = self.images[self.frame//4+4+4] if self.change_y < 0: self.frame += 1 if self.frame > 3*4: self.frame = 0 self.image = self.images[self.frame//4+4+4+4] score = 0 # initialize pyGame pygame.init() # 800x600 sized screen global screen screen = pygame.display.set_mode([800, 600]) screen.fill(black) #bg_tile_img = pygame.image.load('images/map/grass.png').convert_alpha() #draw_background(screen, bg_tile_img) #pygame.display.flip() # Set title pygame.display.set_caption('Test') #background = pygame.Surface(screen.get_size()) #background = background.convert() #background.fill(black) # Create the player player = Player( 50,50 ) player.rect.x=50 player.rect.y=50 movingsprites = pygame.sprite.RenderPlain() movingsprites.add(player) # Make the walls. (x_pos, y_pos, width, height) global wall_list wall_list=pygame.sprite.RenderPlain() wall=Wall(0,0,10,600) # left wall wall_list.add(wall) wall=Wall(10,0,790,10) # top wall wall_list.add(wall) #wall=Wall(10,200,100,10) # poke wall wall_list.add(wall) wall=Wall(790,0,10,600) #(x,y,thickness, height) wall_list.add(wall) wall=Wall(10,590,790,10) #(x,y,thickness, height) wall_list.add(wall) f = open('MapMaker.txt') num_lines = sum(1 for line in f) print(num_lines) lineCount = 0 with open("MapMaker.txt") as infile: for line in infile: f = open('MapMaker.txt') print(line) coords = line.split(',') #print(coords[0]) #print(coords[1]) #print(coords[2]) #print(coords[3]) #print(coords[4]) if "tree" in line: print("tree in") wall=insertTree(int(coords[0]),int(coords[1]), int(coords[2]),int(coords[3]),coords[4]) wall_list.add(wall) elif "rock" in line: print("rock in") wall=insertRock(int(coords[0]),int(coords[1]), int(coords[2]),int(coords[3]),coords[4] ) wall_list.add(wall) width = 20 height = 540 height = height - 48 for i in range(0,23): width = width + 32 name = insertTree(width,540,790,10,"tree") #wall_list.add(name) name = insertTree(width,height,690,10,"tree") #wall_list.add(name) CREEP_SPAWN_TIME = 200 # frames creep_spawn = CREEP_SPAWN_TIME clock = pygame.time.Clock() bg_tile_img = pygame.image.load('images/map/grass.png').convert() img_rect = bg_tile_img FIELD_RECT = Rect(50, 50, 700, 500) CREEP_FILENAMES = [ 'images/player/1.png', 'images/player/1.png', 'images/player/1.png'] N_CREEPS = 3 creep_images = [ pygame.image.load(filename).convert_alpha() for filename in CREEP_FILENAMES] explosion_img = pygame.image.load('images/map/tree.png').convert_alpha() explosion_images = [ explosion_img, pygame.transform.rotate(explosion_img, 90)] creeps = pygame.sprite.RenderPlain() done = False #bg_tile_img = pygame.image.load('images/map/grass.png').convert() #draw_background(screen, bg_tile_img) totalCreeps = 0 remainingCreeps = 3 while done == False: creep_images = pygame.image.load("images/player/1.png").convert() creep_images.set_colorkey(white) draw_background(screen, bg_tile_img) if len(creeps) != N_CREEPS: if totalCreeps < N_CREEPS: totalCreeps = totalCreeps + 1 print(totalCreeps) creeps.add( Creep( screen=screen, creep_image=creep_images, explosion_images=explosion_images, field=FIELD_RECT, init_position=( randint(FIELD_RECT.left, FIELD_RECT.right), randint(FIELD_RECT.top, FIELD_RECT.bottom)), init_direction=(choice([-1, 1]), choice([-1, 1])), speed=0.01)) for creep in creeps: creep.update(60,wall_list) creep.draw() for event in pygame.event.get(): if event.type == pygame.QUIT: done=True if event.type == pygame.KEYDOWN: if event.key == pygame.K_LEFT: player.changespeed(-2,0) creep.changespeed(-2,0) if event.key == pygame.K_RIGHT: player.changespeed(2,0) creep.changespeed(2,0) if event.key == pygame.K_UP: player.changespeed(0,-2) creep.changespeed(0,-2) if event.key == pygame.K_DOWN: player.changespeed(0,2) creep.changespeed(0,2) if event.key == pygame.K_ESCAPE: pauseGame() if event.key == pygame.K_1: global currentEditTool currentEditTool = "Tree" changeTool() if event.key == pygame.K_2: global currentEditTool currentEditTool = "Rock" changeTool() if event.type == pygame.KEYUP: if event.key == pygame.K_LEFT: player.changespeed(2,0) creep.changespeed(2,0) if event.key == pygame.K_RIGHT: player.changespeed(-2,0) creep.changespeed(-2,0) if event.key == pygame.K_UP: player.changespeed(0,2) creep.changespeed(0,2) if event.key == pygame.K_DOWN: player.changespeed(0,-2) creep.changespeed(0,-2) if event.type == pygame.MOUSEBUTTONDOWN and pygame.mouse.get_pressed()[0]: for creep in creeps: creep.mouse_click_event(pygame.mouse.get_pos()) if editMap == True: x,y = pygame.mouse.get_pos() if currentEditTool == "Tree": name = insertTree(x-10,y-25, 10 , 10, "tree") wall_list.add(name) wall_list.draw(screen) f = open('MapMaker.txt', "a+") image = pygame.image.load("images/map/tree.png").convert() screen.blit(image, (30,10)) pygame.display.flip() f.write(str(x) + "," + str(y) + ",790,10, tree\n") #f.write("wall=insertTree(" + str(x) + "," + str(y) + ",790,10)\nwall_list.add(wall)\n") elif currentEditTool == "Rock": name = insertRock(x-10,y-25, 10 , 10,"rock") wall_list.add(name) wall_list.draw(screen) f = open('MapMaker.txt', "a+") f.write(str(x) + "," + str(y) + ",790,10,rock\n") #f.write("wall=insertRock(" + str(x) + "," + str(y) + ",790,10)\nwall_list.add(wall)\n") else: None #pygame.display.flip() player.update(wall_list) movingsprites.draw(screen) wall_list.draw(screen) pygame.display.flip() clock.tick(60) pygame.quit()

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  • StreamInsight 2.1, meet LINQ

    - by Roman Schindlauer
    Someone recently called LINQ “magic” in my hearing. I leapt to LINQ’s defense immediately. Turns out some people don’t realize “magic” is can be a pejorative term. I thought LINQ needed demystification. Here’s your best demystification resource: http://blogs.msdn.com/b/mattwar/archive/2008/11/18/linq-links.aspx. I won’t repeat much of what Matt Warren says in his excellent series, but will talk about some core ideas and how they affect the 2.1 release of StreamInsight. Let’s tell the story of a LINQ query. Compile time It begins with some code: IQueryable<Product> products = ...; var query = from p in products             where p.Name == "Widget"             select p.ProductID; foreach (int id in query) {     ... When the code is compiled, the C# compiler (among other things) de-sugars the query expression (see C# spec section 7.16): ... var query = products.Where(p => p.Name == "Widget").Select(p => p.ProductID); ... Overload resolution subsequently binds the Queryable.Where<Product> and Queryable.Select<Product, int> extension methods (see C# spec sections 7.5 and 7.6.5). After overload resolution, the compiler knows something interesting about the anonymous functions (lambda syntax) in the de-sugared code: they must be converted to expression trees, i.e.,“an object structure that represents the structure of the anonymous function itself” (see C# spec section 6.5). The conversion is equivalent to the following rewrite: ... var prm1 = Expression.Parameter(typeof(Product), "p"); var prm2 = Expression.Parameter(typeof(Product), "p"); var query = Queryable.Select<Product, int>(     Queryable.Where<Product>(         products,         Expression.Lambda<Func<Product, bool>>(Expression.Property(prm1, "Name"), prm1)),         Expression.Lambda<Func<Product, int>>(Expression.Property(prm2, "ProductID"), prm2)); ... If the “products” expression had type IEnumerable<Product>, the compiler would have chosen the Enumerable.Where and Enumerable.Select extension methods instead, in which case the anonymous functions would have been converted to delegates. At this point, we’ve reduced the LINQ query to familiar code that will compile in C# 2.0. (Note that I’m using C# snippets to illustrate transformations that occur in the compiler, not to suggest a viable compiler design!) Runtime When the above program is executed, the Queryable.Where method is invoked. It takes two arguments. The first is an IQueryable<> instance that exposes an Expression property and a Provider property. The second is an expression tree. The Queryable.Where method implementation looks something like this: public static IQueryable<T> Where<T>(this IQueryable<T> source, Expression<Func<T, bool>> predicate) {     return source.Provider.CreateQuery<T>(     Expression.Call(this method, source.Expression, Expression.Quote(predicate))); } Notice that the method is really just composing a new expression tree that calls itself with arguments derived from the source and predicate arguments. Also notice that the query object returned from the method is associated with the same provider as the source query. By invoking operator methods, we’re constructing an expression tree that describes a query. Interestingly, the compiler and operator methods are colluding to construct a query expression tree. The important takeaway is that expression trees are built in one of two ways: (1) by the compiler when it sees an anonymous function that needs to be converted to an expression tree, and; (2) by a query operator method that constructs a new queryable object with an expression tree rooted in a call to the operator method (self-referential). Next we hit the foreach block. At this point, the power of LINQ queries becomes apparent. The provider is able to determine how the query expression tree is evaluated! The code that began our story was intentionally vague about the definition of the “products” collection. Maybe it is a queryable in-memory collection of products: var products = new[]     { new Product { Name = "Widget", ProductID = 1 } }.AsQueryable(); The in-memory LINQ provider works by rewriting Queryable method calls to Enumerable method calls in the query expression tree. It then compiles the expression tree and evaluates it. It should be mentioned that the provider does not blindly rewrite all Queryable calls. It only rewrites a call when its arguments have been rewritten in a way that introduces a type mismatch, e.g. the first argument to Queryable.Where<Product> being rewritten as an expression of type IEnumerable<Product> from IQueryable<Product>. The type mismatch is triggered initially by a “leaf” expression like the one associated with the AsQueryable query: when the provider recognizes one of its own leaf expressions, it replaces the expression with the original IEnumerable<> constant expression. I like to think of this rewrite process as “type irritation” because the rewritten leaf expression is like a foreign body that triggers an immune response (further rewrites) in the tree. The technique ensures that only those portions of the expression tree constructed by a particular provider are rewritten by that provider: no type irritation, no rewrite. Let’s consider the behavior of an alternative LINQ provider. If “products” is a collection created by a LINQ to SQL provider: var products = new NorthwindDataContext().Products; the provider rewrites the expression tree as a SQL query that is then evaluated by your favorite RDBMS. The predicate may ultimately be evaluated using an index! In this example, the expression associated with the Products property is the “leaf” expression. StreamInsight 2.1 For the in-memory LINQ to Objects provider, a leaf is an in-memory collection. For LINQ to SQL, a leaf is a table or view. When defining a “process” in StreamInsight 2.1, what is a leaf? To StreamInsight a leaf is logic: an adapter, a sequence, or even a query targeting an entirely different LINQ provider! How do we represent the logic? Remember that a standing query may outlive the client that provisioned it. A reference to a sequence object in the client application is therefore not terribly useful. But if we instead represent the code constructing the sequence as an expression, we can host the sequence in the server: using (var server = Server.Connect(...)) {     var app = server.Applications["my application"];     var source = app.DefineObservable(() => Observable.Range(0, 10, Scheduler.NewThread));     var query = from i in source where i % 2 == 0 select i; } Example 1: defining a source and composing a query Let’s look in more detail at what’s happening in example 1. We first connect to the remote server and retrieve an existing app. Next, we define a simple Reactive sequence using the Observable.Range method. Notice that the call to the Range method is in the body of an anonymous function. This is important because it means the source sequence definition is in the form of an expression, rather than simply an opaque reference to an IObservable<int> object. The variation in Example 2 fails. Although it looks similar, the sequence is now a reference to an in-memory observable collection: var local = Observable.Range(0, 10, Scheduler.NewThread); var source = app.DefineObservable(() => local); // can’t serialize ‘local’! Example 2: error referencing unserializable local object The Define* methods support definitions of operator tree leaves that target the StreamInsight server. These methods all have the same basic structure. The definition argument is a lambda expression taking between 0 and 16 arguments and returning a source or sink. The method returns a proxy for the source or sink that can then be used for the usual style of LINQ query composition. The “define” methods exploit the compile-time C# feature that converts anonymous functions into translatable expression trees! Query composition exploits the runtime pattern that allows expression trees to be constructed by operators taking queryable and expression (Expression<>) arguments. The practical upshot: once you’ve Defined a source, you can compose LINQ queries in the familiar way using query expressions and operator combinators. Notably, queries can be composed using pull-sequences (LINQ to Objects IQueryable<> inputs), push sequences (Reactive IQbservable<> inputs), and temporal sequences (StreamInsight IQStreamable<> inputs). You can even construct processes that span these three domains using “bridge” method overloads (ToEnumerable, ToObservable and To*Streamable). Finally, the targeted rewrite via type irritation pattern is used to ensure that StreamInsight computations can leverage other LINQ providers as well. Consider the following example (this example depends on Interactive Extensions): var source = app.DefineEnumerable((int id) =>     EnumerableEx.Using(() =>         new NorthwindDataContext(), context =>             from p in context.Products             where p.ProductID == id             select p.ProductName)); Within the definition, StreamInsight has no reason to suspect that it ‘owns’ the Queryable.Where and Queryable.Select calls, and it can therefore defer to LINQ to SQL! Let’s use this source in the context of a StreamInsight process: var sink = app.DefineObserver(() => Observer.Create<string>(Console.WriteLine)); var query = from name in source(1).ToObservable()             where name == "Widget"             select name; using (query.Bind(sink).Run("process")) {     ... } When we run the binding, the source portion which filters on product ID and projects the product name is evaluated by SQL Server. Outside of the definition, responsibility for evaluation shifts to the StreamInsight server where we create a bridge to the Reactive Framework (using ToObservable) and evaluate an additional predicate. It’s incredibly easy to define computations that span multiple domains using these new features in StreamInsight 2.1! Regards, The StreamInsight Team

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  • How to route tree-structured URLs with ASP.NET Routing?

    - by Venemo
    Hello Everyone, I would like to achieve something very similar to this question, with some enhancements. There is an ASP.NET MVC web application. I have a tree of entities. For example, a Page class which has a property called Children, which is of type IList<Page>. (An instance of the Page class corresponds to a row in a database.) I would like to assign a unique URL to every Page in the database. I handle Page objects with a Controller called PageController. Example URLs: http://mysite.com/Page1/ http://mysite.com/Page1/SubPage/ http://mysite.com/Page/ChildPage/GrandChildPage/ You get the picture. So, I'd like every single Page object to have its own URL that is equal to its parent's URL plus its own name. In addition to that, I also would like the ability to map a single Page to the / (root) URL. I would like to apply these rules: If a URL can be handled with any other route, or a file exists in the filesystem in the specified URL, let the default URL mapping happen If a URL can be handled by the virtual path provider, let that handle it If there is no other, map the other URLs to the PageController class I also found this question, and also this one and this one, but they weren't of much help, since they don't provide an explanation about my first two points. I see the following possible soutions: Map a route for each page invidually. This requires me to go over the entire tree when the application starts, and adding an exact match route to the end of the route table. I could add a route with {*path} and write a custom IRouteHandler that handles it, but I can't see how could I deal with the first two rules then, since this handler would get to handle everything. So far, the first solution seems to be the right one, because it is also the simplest. I would really appreciate your thoughts on this. Thank you in advance!

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  • Rails 3 HABTM Strange Association: Project and Employee in a tree.

    - by Mauricio
    Hi guys I have to adapt an existing model to a new relation. I have this: A Project has many Employees. the Employees of a Project are organized in some kind of hierarchy (nothing fancy, I resolved this adding a parent_id for each employee to build the 'tree') class Employee < AR:Base belongs_to :project belongs_to :parent, :class_name => 'Employee' has_many :childs, :class_name => 'Employee', :foreign_column => 'parent_id' end class Project < AR:Base has_many :employees, end That worked like a charm, now the new requirement is: The Employees can belong to many Projects at the same time, and the hierarchy will be different according to the project. So I though I will need a new table to build the HABTM, and a new class to access the parent_id to build the tree. Something like class ProjectEmployee < AR:Base belongs_to :project belongs_to :employee belongs_to :parent, :class_name => 'Employee' # <--- ?????? end class Project < AR:Base has_many :project_employee has_many :employees, :through => :project_employee end class Employee < AR:Base has_many :project_employee has_many :projects, :through => :project_employee end How can I access the parent and the childs of an employee for a given project? I need to add and remove childs as wish from the employees of a project. Thank you!

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  • Java Iterators - Trying to get a for each loop to work

    - by CS Student
    So I have a Tree<E> class where E is the datatype held and organized by the tree. I'd like to iterate through the Tree like this, or in a way similar to this: 1. Tree<String> tree=new Tree<String>(); 2. ...add some nodes... 3. for (String s : tree) 4. System.out.println(s); It gives me an error on line 3 though. Incompatible types required: java.lang.String found: java.lang.Object The following works fine and as expected though, performing a proper in-order traversal of the tree and printing each node out as it should: for (TreeIterator<String> i = tree.iterator(); i.hasNext(); ) System.out.println(i.next()); Any idea what I'm doing wrong? Do you need to see more of the code?

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  • How to focus a control in an MDIParent when all child windows have closed?

    - by Tim Gradwell
    I have a control in my parent mdi form which I wish to be given the focus if all mdi children have closed. I've tried hooking into the child form's FormClosed event and setting the focus from there but when I test it, my control is not left with focus when I close the mdi child. Can anyone tell me what I'm missing? In the sample below, "first focus" gets hit and does its job correctly (if I comment out the first focus line, my tree does not get focus on startup, so it must be doing its job, right?) Unfortunately, even though "second focus" gets hit, my tree does not end up with the focus when I close the child window. Sample using System; using System.Windows.Forms; namespace mdiFocus { class ParentForm : Form { public ParentForm() { IsMdiContainer = true; tree = new TreeView(); tree.Nodes.Add("SomeNode"); tree.Dock = DockStyle.Left; Controls.Add(tree); } protected override void OnShown(EventArgs e) { Form child = new Form(); child.MdiParent = this; child.Show(); child.FormClosed += new FormClosedEventHandler(child_FormClosed); tree.Focus(); // first focus works ok } void child_FormClosed(object sender, FormClosedEventArgs e) { tree.Focus(); // second focus doesn't seem to work, even though it is hit :( } TreeView tree; } static class Program { [STAThread] static void Main() { Application.Run(new ParentForm()); } } }

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  • I want to consolidate two sites into a third. Will my search engine rankings be penalized if I rewrite and redirect pages one by one?

    - by Patrick Kenny
    I have two Drupal sites with different content-- let's call them Apple and Orange. I recently developed a much more sophisticated third Drupal site-- let's call it Tree. For a large number of reasons, the content on Apple and Orange is useful for the users of Tree, so I want to move the content to Tree. However, much of the content is out of date. (This whole process took about five years.) To update the content, I will rewrite it one article at a time myself. Now here's my question: if I move the articles one by one (as I rewrite them) and then redirect the old articles (using a 301 redirect) on Apple/Orange to the new site on Tree, will this have a huge negative effect on my search engine rankings? Is there a good way to redirect among sites when they merge like this, or would I be better off keeping the old articles on Apple/Orange and simply linking them to the new, rewritten articles on Tree?

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  • Jquery hiding all descendents of a ul tag...showing child elements as tree menu...

    - by Ronedog
    I want to hide all the descendents of the "ul" for my tree menu when the page loads up, then as each "main" "li" link is clicked display the direct child, and if the direct child has children (grandchild), when the the "Child" is clicked I want it to show the "grandchild" elements. should be simple, but some how I screwed things up and when i click on the main "li" (Heading 1) it displays all of the descendents (Including the "Sub page A - 1"), instead of just the direct children ("Sub Page A"). Which I think means the children, grandchildren, etc. were never hidden to begin with with the .hide(). What I really want to happen is to hide all the descendents (except the main top-level headings) and as I walk down the tree display the children as needed. Any tips on how to make this work? Here's the HTML: <ul id="nav"> <li>Heading 1 <ul> <li>Sub page A <ul> <li>Sub page A - 1</li> <li>Sub page A - 3</li> <li>Sub page A - 2</li> </ul> </li> <li>Sub page B</li> <li>Sub page C</li> </ul> </li> <li>Heading 2 <ul> <li>Sub page D</li> <li>Sub page E</li> <li>Sub page F</li> </ul> </li> <li>Heading 3 <ul> <li>Sub page G</li> <li>Sub page H</li> <li>Sub page I</li> </ul> </li> Here's my Jquery: $(function(){ $('#nav ul').hide(); //Supposed to Hide all <ul> tags for all descendents, but doesn't work $('#nav>li').mouseover(function(){ $(this).addClass("a_hand") }); //Add the class that displays the hand $('#nav>li').toggle(function() { $(this).find('ul').slideDown(200); }, function() { $(this).find('ul').slideUp(200); });//END TOGGLE });//END MAIN FUNCTION thanks.

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  • Android Eclipse test projects cannot be used with a project being built in an Android build tree

    - by orospakr
    An Android Java project placed in a git repository and built in an Android tree in /packages/apps needs to have the project files located at the root of the git repository. This is problematic for creating a complementary Test project, which should ideally be included in the same git repository so commits are atomic for both code and tests. Eclipse gets very unhappy if you include the Test project as a subdirectory. Is there an appropriate approach for dealing with this other than creating a second repository?

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  • How to write a recursive function that returns a linked list of nodes, when given a binary tree of n

    - by Jian Lin
    I was once asked of this in an interview: How to write a recursive function that returns a linked list of nodes, when given a binary tree of nodes? (flattening the data) For some reason, I tend to need more than 3 to 5 minutes to solve any recursive problem. Usually, 15 to 20 minutes will be more like it. How could we attack this problem, such as a very systematic way of reaching a solution, so that they can be solved in 3 to 5 minute time frame?

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  • Calculate the Hilbert value of a point for use in a Hilbert R-Tree?

    - by wrt
    I have an application where a Hilbert R-Tree (wikipedia) (citeseer) would seem to be an appropriate data structure. Specifically, it requires reasonably fast spatial queries over a data set that will experience a lot of updates. However, as far as I can see, none of the descriptions of the algorithms for this data structure even mention how to actually calculate the requisite Hilbert Value; which is the distance along a Hilbert Curve to the point. So any suggestions for how to go about calculating this?

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  • In Ant, copy all files from a tree of folders into a single folder?

    - by Sam Washburn
    Is it possible to use Ant to copy all the files (not folders) from a hierarchy of folders into one destination folder? For instance, I have a tree like this: res |-images | |-fg.png | +-bg.png +-sounds +-music.mp3 And I would like a result like this: data |-fg.png |-bg.png +-music.mp3 The way things are named, filename conflicts are not an issue. Is this possible to do with Ant?

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  • Where should I initialize variables for an OO Recursive Descent Parse Tree?

    - by Vasto
    I'd like to preface this by stating that this is for a class, so please don't solve this for me. One of my labs for my cse class is creating an interpreter for a BNF that was provided. I understand most of the concepts, but I'm trying to build up my tree and I'm unsure where to initialize values. I've tried in both the constructor, and in the methods but Eclipse's debugger still only shows the left branch, even though it runs through completely. Here is my main procedure so you can get an idea of how I'm calling the methods. public class Parser { public static void main(String[] args) throws IOException { FileTokenizer instance = FileTokenizer.Instance(); FileTokenizer.main(args); Prog prog = new Prog(); prog.ParseProg(); prog.PrintProg(); prog.ExecProg(); } Now here is My Prog class: public class Prog { private DeclSeq ds; private StmtSeq ss; Prog() { ds = new DeclSeq(); ss = new StmtSeq(); } public void ParseProg() { FileTokenizer instance = FileTokenizer.Instance(); instance.skipToken(); //Skips program (1) // ds = new DeclSeq(); ds.ParseDS(); instance.skipToken(); //Skips begin (2) // ss = new StmtSeq(); ss.ParseSS(); instance.skipToken(); } I've tried having Prog() { ds = null; ss = null; } public void ParseProg() { FileTokenizer instance = FileTokenizer.Instance(); instance.skipToken(); //Skips program (1) ds = new DeclSeq(); ds.ParseDS(); ... But it gave me the same error. I need the parse tree built up so I can do a pretty print and an execute command, but like I said, I only get the left branch. Any help would be appreciated. Explanations why are even more so appreciated. Thank you, Vasto

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