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• Select row After UIPickerView is loaded

  - by Steve Gibson

  I have an iphone database app that loads a UIPickerView with data from a table. I want to set the selected row to a particular row from the data in another table. for example: Lets say I have a UIPickerView that is loaded with X number of names of the iPhone users friends (the number of names is variable, could be 1 or 1000 and all are entered into the DB by the user). The iPhone user has a preference set that their current best friend is TED. I want the UIPickerView to be position to TED when displayed. Where do I call selectRow? I tried in viewDidAppear but it was never called, in titleForRow which caused all kinds of strange behavior. viewDidLoad and viewWillAppear are out of the question because I don't know what's in the datasource to the picker yet. Thanks in advance.

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• How do I convert decimal numbers to binary in Perl?

  - by David

  I am trying to make a program that converts decimal numbers or text into binary numbers in perl. The program asks for user input of a character or string , and then prints out the result to the console. How do I do this? My code I have been working on is below, but i cannot seem to fix it. print "Enter a number to convert: "; chomp($decimal = <STDIN>); print "\nConverting $number to binary...\n"; $remainder = $decimal%2; while($decimal > 0) { $decimal/2; print $remainder; }

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• Hashing words to numbers with respect to definition

  - by thornate

  As part of a larger project, I need to read in text and represent each word as a number. For example, if the program reads in "Every good boy deserves fruit", then I would get a table that converts 'every' to '1742', 'good' to '977513', etc. Now, obviously I can just use a hashing algorithm to get these numbers. However, it would be more useful if words with similar meanings had numerical values close to each other, so that 'good' becomes '6827' and 'great' becomes '6835', etc. As another option, instead of a simple integer representing each number, it would be even better to have a vector made up of multiple numbers, eg (lexical_category, tense, classification, specific_word) where lexical_category is noun/verb/adjective/etc, tense is future/past/present, classification defines a wide set of general topics and specific_word is much the same as described in the previous paragraph. Does any such an algorithm exist? If not, can you give me any tips on how to get started on developing one myself? I code in C++.

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• Hive NR map progress inconsistent and regurlarly restart from 0%

  - by user92471

  I have a Yarn MR (with two ec2 instances to mapreduce) job on a dataset of approximately a thousand avro records, and the map phase is behaving erratically. See the progress below. Of course i checked the logs on resourcemanager and nodemanagers and saw nothing suspicious, but these logs are too verbose What is going on there ? hive> select * from nikon where qs_cs_s_aid='VIEW' limit 10; Total MapReduce jobs = 1 Launching Job 1 out of 1 Number of reduce tasks is set to 0 since there's no reduce operator Starting Job = job_1352281315350_0020, Tracking URL = http://blabla.ec2.internal:8088/proxy/application_1352281315350_0020/ Kill Command = /usr/lib/hadoop/bin/hadoop job -Dmapred.job.tracker=blabla.com:8032 -kill job_1352281315350_0020 Hadoop job information for Stage-1: number of mappers: 4; number of reducers: 0 2012-11-07 11:14:40,976 Stage-1 map = 0%, reduce = 0% 2012-11-07 11:15:06,136 Stage-1 map = 1%, reduce = 0%, Cumulative CPU 10.38 sec 2012-11-07 11:15:07,253 Stage-1 map = 1%, reduce = 0%, Cumulative CPU 12.18 sec 2012-11-07 11:15:08,371 Stage-1 map = 1%, reduce = 0%, Cumulative CPU 12.18 sec 2012-11-07 11:15:09,491 Stage-1 map = 1%, reduce = 0%, Cumulative CPU 12.18 sec 2012-11-07 11:15:10,643 Stage-1 map = 2%, reduce = 0%, Cumulative CPU 15.42 sec (...) 2012-11-07 11:15:35,441 Stage-1 map = 28%, reduce = 0%, Cumulative CPU 37.77 sec 2012-11-07 11:15:36,486 Stage-1 map = 28%, reduce = 0%, Cumulative CPU 37.77 sec here restart at 16% ? 2012-11-07 11:15:37,692 Stage-1 map = 16%, reduce = 0%, Cumulative CPU 21.15 sec 2012-11-07 11:15:38,815 Stage-1 map = 16%, reduce = 0%, Cumulative CPU 21.15 sec 2012-11-07 11:15:39,865 Stage-1 map = 16%, reduce = 0%, Cumulative CPU 21.15 sec 2012-11-07 11:15:41,064 Stage-1 map = 18%, reduce = 0%, Cumulative CPU 22.4 sec 2012-11-07 11:15:42,181 Stage-1 map = 18%, reduce = 0%, Cumulative CPU 22.4 sec 2012-11-07 11:15:43,299 Stage-1 map = 18%, reduce = 0%, Cumulative CPU 22.4 sec here restart at 0% ? 2012-11-07 11:15:44,418 Stage-1 map = 0%, reduce = 0% 2012-11-07 11:16:02,076 Stage-1 map = 1%, reduce = 0%, Cumulative CPU 6.86 sec 2012-11-07 11:16:03,193 Stage-1 map = 1%, reduce = 0%, Cumulative CPU 6.86 sec 2012-11-07 11:16:04,259 Stage-1 map = 2%, reduce = 0%, Cumulative CPU 8.45 sec (...) 2012-11-07 11:16:31,291 Stage-1 map = 22%, reduce = 0%, Cumulative CPU 35.34 sec 2012-11-07 11:16:32,414 Stage-1 map = 26%, reduce = 0%, Cumulative CPU 37.93 sec here restart at 11% ? 2012-11-07 11:16:33,459 Stage-1 map = 11%, reduce = 0%, Cumulative CPU 19.53 sec 2012-11-07 11:16:34,507 Stage-1 map = 11%, reduce = 0%, Cumulative CPU 19.53 sec 2012-11-07 11:16:35,731 Stage-1 map = 13%, reduce = 0%, Cumulative CPU 21.47 sec (...) 2012-11-07 11:16:46,839 Stage-1 map = 17%, reduce = 0%, Cumulative CPU 24.14 sec here restart at 0% ? 2012-11-07 11:16:47,939 Stage-1 map = 0%, reduce = 0% 2012-11-07 11:16:56,653 Stage-1 map = 1%, reduce = 0%, Cumulative CPU 7.54 sec 2012-11-07 11:16:57,814 Stage-1 map = 1%, reduce = 0%, Cumulative CPU 7.54 sec (...) Needless to say the job crashes after some time with an Error: java.io.IOException: java.io.IOException: java.lang.ArrayIndexOutOfBoundsException: -56

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• R regex to validate user input is correct.

  - by John

  I'm trying to practice writing better code, so I wanted to validate my input sequence with regex to make sure that the first thing I get is a single letter A to H only, and the second is a number 1 to 12 only. I'm new to regex and not sure what the expression should look like. I'm also not sure what type of error R would throw if this is invalidated? In Perl it would be something like this I think: =~ m/([A-M]?))/) Here is what I have so far for R: input_string = "A1" first_well_row = unlist(strsplit(input_string, ""))[1] # get the letter out first_well_col = unlist(strsplit(input_string, ""))[2] # get the number out

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• OCR an RSA key fob (security token)

  - by user130582

  I put together a quick WinForm/embedded IE browser control which logs into our company's bank website each morning and scrapes/exports the desired deposit information (the bank is a smallish regional bank). Since we have a few dozen "pseudoaccounts" that draw from the same master account, this actually takes 10-15 minutes to retrieve. Anyway, the only problem is that our business bank account reuires an RSA security token (http://www.rsa.com/node.aspx?id=1156)--if you are not familiar, it is a small device which shows a random 6 digit number every 15(?) seconds, so I have to prompt for this value before starting. This is on top of the website's login based security model, so even if you create a read-only account that can't do anything, you still have to put the RSA number in. We have 5 of these tokens for different people in the company. From our perspective this is nusiance security. I was joking about using a web camera to OCR the digits from the key fob so they didn't have to type it in -- mainly so that the scraping/export would be done before anyone arrives in the morning. Well, they asked if I could really do it. So now I ask you, how hard (how many hours) do you think it would take to OCR these digits reliably from a JPEG image produced by the camera? I already know I can get the JPEG easily. I think you get 3 tries to log in, so it really needs to hit a 99% accuracy rate. I could work on this on my off time, but they don't want me to put more than a few hours into it, so I want to leverage as much existing code as possible. This is a 7-segment display (like an alarm clock) so it's not exactly text that an OCR package would be used to seeing. Also--there is a countdown timer on the side of the display; typically when it is down to 1 bar, you wait until the next number appears and it starts over at 5 bars (like signal strength on your cell phone). So this would need to be OCRd as well but it is not text. Anyway the more I think about it as I type this, the less convinced I am that I can truly get this right, so maybe I should just work on it in my spare time?

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• Python - calculate multinomial probability density functions on large dataset?

  - by Seafoid

  Hi, I originally intended to use MATLAB to tackle this problem but the inbuilt functions has limitations that do not suit my goal. The same limitation occurs in NumPy. I have two tab-delimited files. The first is a file showing amino acid residue, frequency and count for an in-house database of protein structures, i.e. A 0.25 1 S 0.25 1 T 0.25 1 P 0.25 1 The second file consists of quadruplets of amino acids and the number of times they occur, i.e. ASTP 1 Note, there are 8,000 such quadruplets. Based on the background frequency of occurence of each amino acid and the count of quadruplets, I aim to calculate the multinomial probability density function for each quadruplet and subsequently use it as the expected value in a maximum likelihood calculation. The multinomial distribution is as follows: f(x|n, p) = n!/(x1!*x2!*...*xk!)*((p1^x1)*(p2^x2)*...*(pk^xk)) where x is the number of each of k outcomes in n trials with fixed probabilities p. n is 4 four in all cases in my calculation. I have created three functions to calculate this distribution. # functions for multinomial distribution def expected_quadruplets(x, y): expected = x*y return expected # calculates the probabilities of occurence raised to the number of occurrences def prod_prob(p1, a, p2, b, p3, c, p4, d): prob_prod = (pow(p1, a))*(pow(p2, b))*(pow(p3, c))*(pow(p4, d)) return prob_prod # factorial() and multinomial_coefficient() work in tandem to calculate C, the multinomial coefficient def factorial(n): if n <= 1: return 1 return n*factorial(n-1) def multinomial_coefficient(a, b, c, d): n = 24.0 multi_coeff = (n/(factorial(a) * factorial(b) * factorial(c) * factorial(d))) return multi_coeff The problem is how best to structure the data in order to tackle the calculation most efficiently, in a manner that I can read (you guys write some cryptic code :-)) and that will not create an overflow or runtime error. To data my data is represented as nested lists. amino_acids = [['A', '0.25', '1'], ['S', '0.25', '1'], ['T', '0.25', '1'], ['P', '0.25', '1']] quadruplets = [['ASTP', '1']] I initially intended calling these functions within a nested for loop but this resulted in runtime errors or overfloe errors. I know that I can reset the recursion limit but I would rather do this more elegantly. I had the following: for i in quadruplets: quad = i[0].split(' ') for j in amino_acids: for k in quadruplets: for v in k: if j[0] == v: multinomial_coefficient(int(j[2]), int(j[2]), int(j[2]), int(j[2])) I haven'te really gotten to how to incorporate the other functions yet. I think that my current nested list arrangement is sub optimal. I wish to compare the each letter within the string 'ASTP' with the first component of each sub list in amino_acids. Where a match exists, I wish to pass the appropriate numeric values to the functions using indices. Is their a better way? Can I append the appropriate numbers for each amino acid and quadruplet to a temporary data structure within a loop, pass this to the functions and clear it for the next iteration? Thanks, S :-)

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• How to Solve N-Queens Problem in Scheme?

  - by Philip

  Hi, I'm stuck on the extended exercise 28.2 of How to Design Programs. Here is the link to the question: http://www.htdp.org/2003-09-26/Book/curriculum-Z-H-35.html#node_chap_28 I used a vector of true or false values to represent the board instead of using a list. This is what I've got which doesn't work: #lang Scheme (define-struct posn (i j)) ;takes in a position in i, j form and a board and returns a natural number that represents the position in index form ;example for board xxx ; xxx ; xxx ;(0, 1) - 1 ;(2, 1) - 7 (define (board-ref a-posn a-board) (+ (* (sqrt (vector-length a-board)) (posn-i a-posn)) (posn-j a-posn))) ;reverse of the above function ;1 - (0, 1) ;7 - (2, 1) (define (get-posn n a-board) (local ((define board-length (sqrt (vector-length a-board)))) (make-posn (floor (/ n board-length)) (remainder n board-length)))) ;determines if posn1 threatens posn2 ;true if they are on the same row/column/diagonal (define (threatened? posn1 posn2) (cond ((= (posn-i posn1) (posn-i posn2)) #t) ((= (posn-j posn1) (posn-j posn2)) #t) ((= (abs (- (posn-i posn1) (posn-i posn2))) (abs (- (posn-j posn1) (posn-j posn2)))) #t) (else #f))) ;returns a list of positions that are not threatened or occupied by queens ;basically any position with the value true (define (get-available-posn a-board) (local ((define (get-ava index) (cond ((= index (vector-length a-board)) '()) ((vector-ref a-board index) (cons index (get-ava (add1 index)))) (else (get-ava (add1 index)))))) (get-ava 0))) ;consume a position in the form of a natural number and a board ;returns a board after placing a queen on the position of the board (define (place n a-board) (local ((define (foo x) (cond ((not (board-ref (get-posn x a-board) a-board)) #f) ((threatened? (get-posn x a-board) (get-posn n a-board)) #f) (else #t)))) (build-vector (vector-length a-board) foo))) ;consume a list of positions in the form of natural number and consumes a board ;returns a list of boards after placing queens on each of the positions on the board (define (place/list alop a-board) (cond ((empty? alop) '()) (else (cons (place (first alop) a-board) (place/list (rest alop) a-board))))) ;returns a possible board after placing n queens on a-board ;returns false if impossible (define (placement n a-board) (cond ((zero? n) a-board) (else (local ((define available-posn (get-available-posn a-board))) (cond ((empty? available-posn) #f) (else (or (placement (sub1 n) (place (first available-posn) a-board)) (placement/list (sub1 n) (place/list (rest available-posn) a-board))))))))) ;returns a possible board after placing n queens on a list of boards ;returns false if all the boards are not valid (define (placement/list n boards) (cond ((empty? boards) #f) ((zero? n) (first boards)) ((not (boolean? (placement n (first boards)))) (first boards)) (else (placement/list n (rest boards)))))

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• Spawning BackgroundWorkers

  - by washtik

  We have a business case that would be perfect for multiple BackgroundWorkers. As an example, we have a form with a "Save" button on it. Normally we would run all the save commands (Save is an example) synchronously and then close the form. We would like to now split the work onto separate threads using backgroundworker. We will loop through each "Save" required (could be many and/or different number of commands that need executing) creating a BackgroundWorker for each command required. The question is ... how do we wait for ALL the BackgroundWorkers to complete before we close the form. We understand how to wait for a single BackgroundWorker to complete but when we have X number of BackgroundWorkers operating, how do we wait until all are complete before closing the UI form?

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• Max TCP Connections to a machine

  - by A9S6

  I am creating a Windows Service in .NET to which N number of client can connect. The service starts a TCP listener and accepts the client connections. The problem I am facing is that I can only open 10 connections to this service. The listener::AcceptTcpClient() method accepts only 10 connection and throws an exception for 11th one. The client application uses the System.Net.Sockets.TcpClient class and the service is using System.Net.Sockets.TcpListener class. This is the exception that I am getting when I try to make a number of connections in a for loop to this service (after the 10th connection is made): "Unable to read data from Transport connection: An exsting connection was forcibly closed by remote host"

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• How can I read individual lines of a CSV file into a string array, to then be selectively displayed

  - by Ryan

  I need your help, guys! :| I've got myself a CSV file with the following contents: 1,The Compact,1.8GHz,1024MB,160GB,440 2,The Medium,2.4GHz,1024MB,180GB,500 3,The Workhorse,2.4GHz,2048MB,220GB,650 It's a list of computer systems, basically, that the user can purchase. I need to read this file, line-by-line, into an array. Let's call this array csvline(). The first line of the text file would stored in csvline(0). Line two would be stored in csvline(1). And so on. (I've started with zero because that's where VB starts its arrays). A drop-down list would then enable the user to select 1, 2 or 3 (or however many lines/systems are stored in the file). Upon selecting a number - say, 1 - csvline(0) would be displayed inside a textbox (textbox1, let's say). If 2 was selected, csvline(1) would be displayed, and so on. It's not the formatting I need help with, though; that's the easy part. I just need someone to help teach me how to read a CSV file line-by-line, putting each line into a string array - csvlines(count) - then increment count by one so that the next line is read into another slot. So far, I've been able to paste the numbers of each system into an combobox: Using csvfileparser As New Microsoft.VisualBasic.FileIO.TextFieldParser _ ("F:\folder\programname\programname\bin\Debug\systems.csv") Dim csvalue As String() csvfileparser.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited csvfileparser.Delimiters = New String() {","} While Not csvfileparser.EndOfData csvalue = csvfileparser.ReadFields() combobox1.Items.Add(String.Format("{1}{0}", _ Environment.NewLine, _ csvalue(0))) End While End Using But this only selects individual values. I need to figure out how selecting one of these numbers in the combobox can trigger textbox1 to be appended with just that line (I can handle the formatting, using the string.format stuff). If I try to do this using csvalue = csvtranslator.ReadLine , I get the following error message: "Error 1 Value of type 'String' cannot be converted to '1-dimensional array of String'." If I then put it as an array, ie: csvalue() = csvtranslator.ReadLine , I then get a different error message: "Error 1 Number of indices is less than the number of dimensions of the indexed array." What's the knack, guys? I've spent hours trying to figure this out. Please go easy on me - and keep any responses ultra-simple for my newbie brain - I'm very new to all this programming malarkey and just starting out! :)

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• Figuring out the required MaxReceivedMessageSize in WCF with NetTcpBinding

  - by Flo

  I'm using NetTcpBinding in WCF and i want to send a Stream which does not exceed the size of 1 MB. I have set the MaxReceivedMessageSize to a really high number and that works fine of course. But I am curious: Does setting the MaxReceivedMessageSize to a very hight number have any (negative) impact or would it be useful to set it just above the size I actually want to send/receive? What kind of overhead can I expect when using the NetTcpBinding to transfer a stream? Meaning: when I send a stream of 1 MB, how large does my MaxReceivedMessageSize has to be?

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• Setting the position within a spinner

  - by eric

  Good Afternoon, I have a spinner array containing 3 spinners. Each spinner is populated via a res string array. Each array contains the numbers 1-100. When the activity starts each spinner contains a string array of 1-100 and when you click on a spinner the first choice is 1. Say a user picks 25 on the first spinner. I'd like the 2nd spinner to show 25 as the starting point for scrolling when the spinner is clicked but not fire the spinner. The 2nd spinner would still contain the array 1-100 though so a user could scroll down to a lessor number if the wanted to. I've tried using setSelection but that causes the 2nd spinner to fire causing undesirable effects (an edit box is populated with the 2nd number even though the user hasn't clicked the 2nd spinner). I would like the 2nd spinner to just show 25 as the starting point. How do I do this?

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• Win32 API Question

  - by Lalit_M

  We have developed a ASP.NET web application and has implemented a custom authentication solution using active directory as the credentials store. Our front end application uses a normal login form to capture the user name and password and leverages the Win32 LogonUser method to authenticate the user’s credentials. When we are calling the LogonUser method, we are using the LOGON32_LOGON_NETWORK as the logon type. The issue we have found is that user profile folders are being created under the C:\Users folder of the web server. The folder seems to be created when a new user who has never logged on before is logging in for the first time. As the number of new users logging into the application grows, disk space is shrinking due to the large number of new user folders getting created. Has anyone seen this behavior with the Win32 LogonUser method? Does anyone know how to disable this behavior?

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• Graphing a dataset

  - by brooke

  What type of graphical tool shows the shape of the data set by stacking x's above each data value on q number line?

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• EF Code First to SQL Azure

  - by Predrag Pejic

  I am using EF Code First to create a database on local .\SQLEXPRESS. Among others. I have these 2 classes: public class Shop { public int ShopID { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a name!")] [MaxLength(25, ErrorMessage = "Name must be 25 characters or less")] public string Name { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter an address!")] [MaxLength(30, ErrorMessage = "Address must be 30 characters or less")] public string Address { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a valid city name!")] [MaxLength(30, ErrorMessage = "City name must be 30 characters or less")] public string City { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a phone number!")] [MaxLength(14, ErrorMessage = "Phone number must be 14 characters or less")] public string Phone { get; set; } [MaxLength(100, ErrorMessage = "Description must be 50 characters or less")] public string Description { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a WorkTime!")] public DateTime WorkTimeBegin { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a WorkTime!")] public DateTime WorkTimeEnd { get; set; } public DateTime? SaturdayWorkTimeBegin { get; set; } public DateTime? SaturdayWorkTimeEnd { get; set; } public DateTime? SundayWorkTimeBegin { get; set; } public DateTime? SundayWorkTimeEnd { get; set; } public int ShoppingPlaceID { get; set; } public virtual ShoppingPlace ShoppingPlace { get; set; } public virtual ICollection<Category> Categories { get; set; } } public class ShoppingPlace { [Key] public int ShopingplaceID { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a name!")] [MaxLength(25, ErrorMessage = "Name must be 25 characters or less")] public string Name { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter an address!")] [MaxLength(50, ErrorMessage = "Address must be 50 characters or less")] public string Address { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a city name!")] [MaxLength(30, ErrorMessage = "City must be 30 characters or less")] public string City { get; set; } [Required(AllowEmptyStrings = false, ErrorMessage = "You must enter a valid phone number!")] [MaxLength(14, ErrorMessage = "Phone number must be 14 characters or less")] public string Phone { get; set; } public int ShoppingCenterID { get; set; } public virtual ShoppingCenter ShoppingCenter { get; set; } public virtual ICollection<Shop> Shops { get; set; } } and a method in DbContext: modelBuilder.Entity<Item>() .HasRequired(p => p.Category) .WithMany(a => a.Items) .HasForeignKey(a => a.CategoryID) .WillCascadeOnDelete(false); modelBuilder.Entity<Category>() .HasRequired(a => a.Shop) .WithMany(a => a.Categories) .HasForeignKey(a => a.ShopID) .WillCascadeOnDelete(false); modelBuilder.Entity<Shop>() .HasOptional(a => a.ShoppingPlace) .WithMany(a => a.Shops) .HasForeignKey(a => a.ShoppingPlaceID) .WillCascadeOnDelete(false); modelBuilder.Entity<ShoppingPlace>() .HasOptional(a => a.ShoppingCenter) .WithMany(a => a.ShoppingPlaces) .HasForeignKey(a => a.ShoppingCenterID) .WillCascadeOnDelete(false); Why I can't create Shop without creating and populating ShopingPlace. How to achieve that? EDIT: Tried with: modelBuilder.Entity<Shop>() .HasOptional(a => a.ShoppingPlace) .WithOptionalPrincipal(); modelBuilder.Entity<ShoppingPlace>() .HasOptional(a => a.ShoppingCenter) .WithOptionalPrincipal(); and it passed, but what is the difference? And why in SQL Server i am allowed to see ShoppingPlaceID and ShoppingPlace_ShopingPlaceID when in the case of Item and Category i see only one?

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• How to optimize my PageRank calculation?

  - by asmaier

  In the book Programming Collective Intelligence I found the following function to compute the PageRank: def calculatepagerank(self,iterations=20): # clear out the current PageRank tables self.con.execute("drop table if exists pagerank") self.con.execute("create table pagerank(urlid primary key,score)") self.con.execute("create index prankidx on pagerank(urlid)") # initialize every url with a PageRank of 1.0 self.con.execute("insert into pagerank select rowid,1.0 from urllist") self.dbcommit() for i in range(iterations): print "Iteration %d" % i for (urlid,) in self.con.execute("select rowid from urllist"): pr=0.15 # Loop through all the pages that link to this one for (linker,) in self.con.execute("select distinct fromid from link where toid=%d" % urlid): # Get the PageRank of the linker linkingpr=self.con.execute("select score from pagerank where urlid=%d" % linker).fetchone()[0] # Get the total number of links from the linker linkingcount=self.con.execute("select count(*) from link where fromid=%d" % linker).fetchone()[0] pr+=0.85*(linkingpr/linkingcount) self.con.execute("update pagerank set score=%f where urlid=%d" % (pr,urlid)) self.dbcommit() However, this function is very slow, because of all the SQL queries in every iteration >>> import cProfile >>> cProfile.run("crawler.calculatepagerank()") 2262510 function calls in 136.006 CPU seconds Ordered by: standard name ncalls tottime percall cumtime percall filename:lineno(function) 1 0.000 0.000 136.006 136.006 <string>:1(<module>) 1 20.826 20.826 136.006 136.006 searchengine.py:179(calculatepagerank) 21 0.000 0.000 0.528 0.025 searchengine.py:27(dbcommit) 21 0.528 0.025 0.528 0.025 {method 'commit' of 'sqlite3.Connecti 1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler 1339864 112.602 0.000 112.602 0.000 {method 'execute' of 'sqlite3.Connec 922600 2.050 0.000 2.050 0.000 {method 'fetchone' of 'sqlite3.Cursor' 1 0.000 0.000 0.000 0.000 {range} So I optimized the function and came up with this: def calculatepagerank2(self,iterations=20): # clear out the current PageRank tables self.con.execute("drop table if exists pagerank") self.con.execute("create table pagerank(urlid primary key,score)") self.con.execute("create index prankidx on pagerank(urlid)") # initialize every url with a PageRank of 1.0 self.con.execute("insert into pagerank select rowid,1.0 from urllist") self.dbcommit() inlinks={} numoutlinks={} pagerank={} for (urlid,) in self.con.execute("select rowid from urllist"): inlinks[urlid]=[] numoutlinks[urlid]=0 # Initialize pagerank vector with 1.0 pagerank[urlid]=1.0 # Loop through all the pages that link to this one for (inlink,) in self.con.execute("select distinct fromid from link where toid=%d" % urlid): inlinks[urlid].append(inlink) # get number of outgoing links from a page numoutlinks[urlid]=self.con.execute("select count(*) from link where fromid=%d" % urlid).fetchone()[0] for i in range(iterations): print "Iteration %d" % i for urlid in pagerank: pr=0.15 for link in inlinks[urlid]: linkpr=pagerank[link] linkcount=numoutlinks[link] pr+=0.85*(linkpr/linkcount) pagerank[urlid]=pr for urlid in pagerank: self.con.execute("update pagerank set score=%f where urlid=%d" % (pagerank[urlid],urlid)) self.dbcommit() This function is 20 times faster (but uses a lot more memory for all the temporary dictionaries) because it avoids the unnecessary SQL queries in every iteration: >>> cProfile.run("crawler.calculatepagerank2()") 64802 function calls in 6.950 CPU seconds Ordered by: standard name ncalls tottime percall cumtime percall filename:lineno(function) 1 0.004 0.004 6.950 6.950 <string>:1(<module>) 1 1.004 1.004 6.946 6.946 searchengine.py:207(calculatepagerank2 2 0.000 0.000 0.104 0.052 searchengine.py:27(dbcommit) 23065 0.012 0.000 0.012 0.000 {meth 'append' of 'list' objects} 2 0.104 0.052 0.104 0.052 {meth 'commit' of 'sqlite3.Connection 1 0.000 0.000 0.000 0.000 {meth 'disable' of '_lsprof.Profiler' 31298 5.809 0.000 5.809 0.000 {meth 'execute' of 'sqlite3.Connectio 10431 0.018 0.000 0.018 0.000 {method 'fetchone' of 'sqlite3.Cursor' 1 0.000 0.000 0.000 0.000 {range} But is it possible to further reduce the number of SQL queries to speed up the function even more?

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• Python: How to read huge text file into memory

  - by asmaier

  I'm using Python 2.6 on a Mac Mini with 1GB RAM. I want to read in a huge text file $ ls -l links.csv; file links.csv; tail links.csv -rw-r--r-- 1 user user 469904280 30 Nov 22:42 links.csv links.csv: ASCII text, with CRLF line terminators 4757187,59883 4757187,99822 4757187,66546 4757187,638452 4757187,4627959 4757187,312826 4757187,6143 4757187,6141 4757187,3081726 4757187,58197 So each line in the file consists of a tuple of two comma separated integer values. I want to read in the whole file and sort it according to the second column. I know, that I could do the sorting without reading the whole file into memory. But I thought for a file of 500MB I should still be able to do it in memory since I have 1GB available. However when I try to read in the file, Python seems to allocate a lot more memory than is needed by the file on disk. So even with 1GB of RAM I'm not able to read in the 500MB file into memory. My Python code for reading the file and printing some information about the memory consumption is: #!/usr/bin/python # -*- coding: utf-8 -*- import sys infile=open("links.csv", "r") edges=[] count=0 #count the total number of lines in the file for line in infile: count=count+1 total=count print "Total number of lines: ",total infile.seek(0) count=0 for line in infile: edge=tuple(map(int,line.strip().split(","))) edges.append(edge) count=count+1 # for every million lines print memory consumption if count%1000000==0: print "Position: ", edge print "Read ",float(count)/float(total)*100,"%." mem=sys.getsizeof(edges) for edge in edges: mem=mem+sys.getsizeof(edge) for node in edge: mem=mem+sys.getsizeof(node) print "Memory (Bytes): ", mem The output I got was: Total number of lines: 30609720 Position: (9745, 2994) Read 3.26693612356 %. Memory (Bytes): 64348736 Position: (38857, 103574) Read 6.53387224712 %. Memory (Bytes): 128816320 Position: (83609, 63498) Read 9.80080837067 %. Memory (Bytes): 192553000 Position: (139692, 1078610) Read 13.0677444942 %. Memory (Bytes): 257873392 Position: (205067, 153705) Read 16.3346806178 %. Memory (Bytes): 320107588 Position: (283371, 253064) Read 19.6016167413 %. Memory (Bytes): 385448716 Position: (354601, 377328) Read 22.8685528649 %. Memory (Bytes): 448629828 Position: (441109, 3024112) Read 26.1354889885 %. Memory (Bytes): 512208580 Already after reading only 25% of the 500MB file, Python consumes 500MB. So it seem that storing the content of the file as a list of tuples of ints is not very memory efficient. Is there a better way to do it, so that I can read in my 500MB file into my 1GB of memory?

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• Check if a String is a double or an int?

  - by user69514

  I have a string for a Date in the form mm/dd, and I need to check if either the month or day was entered as a double public Date(String dateStr){ int slash = 0; //check slash is present try{ slash = dateStr.indexOf('/'); }catch(StringIndexOutOfBoundsException e){ error = "Invalid date format: " + dateStr; } //check if month is a number try{ month = Integer.parseInt(dateStr.substring(0, slash)); //day = Integer.parseInt(dateStr.substring(slash + 1, dateStr.length())); } catch(NumberFormatException e){ System.out.println("Invalid format for input string: " + dateStr.substring(0, slash)); } //check if day is a number try{ day = Integer.parseInt(dateStr.substring(slash + 1, dateStr.length())); } catch(NumberFormatException e){ System.out.println("Invalid format for input string: " + dateStr.substring(slash + 1, dateStr.length())); } //check if month was entered as a double }

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• iPhone long plist

  - by Zac Altman

  I have some data i want to add in to my app...about 650 categories (includes a name + id number), each with an average of 85 items (each with a name/id number). Will the iPhone support such a large plist? I want to first display the categories in a UITableView, when a category is selected I want to display all of the associated items. Having such a large plist, im not sure if the iPhone will lag when loading the items. At over 51,000 lines it seems like...it might.

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• Getting float values out of PostgreSQL

  - by skymander

  I am having trouble retrieving float/real values out of PostgreSQL. For example, I would like to store: 123456789123456, the retrieve that exact same number with a select statement. table tbl (num real) insert into tbl(num) values('123456789123456'); As it is now, if I "select num from tbl" the result is "1.23457e+14" If I run "select CAST(num AS numeric) as num from tbl" the result is 123457000000000 If I run "select CAST(num AS float) as num from tbl" the result is 123456788103168 (where did this number come from) How on earth can I select the value and get "123456789123456" as the result? Thanks so much in advance

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• Learning Linux screencasts

  - by Dmitriy Nagirnyak

  Hi, I am trying to get started with Linux. There are number of books (many of which are just man pages), some of them provide good overview so I can dig deeper online then. What I would like is to find number of screencasts that would cover basics of Linux commands, server administration, commonly performed tasks etc (no GUI, only terminal). I want to watch the screencasts to "get it quicker" and then use a book or online resources to "dig it deeper". Any recommendations? Thanks, Dmitriy.

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• Implementing google dashboard type interface in asp.net

  - by Sam_Cogan

  I'm looking at implementing a Google IG type dashboard in a .net app. There are a number of options I've found to do this, and i'm trying to establish what is going to be the best to use, in terms of speed, versatility etc. So far the options I am looking at are either to use asp.net webparts and .net Ajax, this would make it quicker to build, but I'm concerned this is going to make the application bulky and slow, or using JQuery, and either .net MVC or Webforms, to custom build an interface. Does anyone have any thoughts on what the best option may be, or any options I may have missed? All I want to do here is to allow users to customise a dashboard with a number of components (which will be user controls). I do also have access to Telerik controls, but I'm not sure if they would be any use here.

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• Control JSON Serialization format of a custom type in .NET

  - by mrjoltcola

  I have a PhoneNumber class that stores a normalized string, and I've defined implicit operators for string <- Phone to simplify treatment of the PhoneNumber as a string. I've also overridden the ToString() method to always return the cleaned version of the number (no hyphens or parentheses or spaces). In any MVC.NET code where I explicitly display the number, I can explicitly call phone.Format(). The problem here is serializing an entity that has a PhoneNumber to JSON; JavaScriptSerializer serializes it as [object Object]. I want to serialize it as a string in (555)555-5555 format. I've looked at writing a custom JavaScriptConverter, but JavaScriptConverter.Serialize() method returns a dictionary of name-value pairs. I don't want PhoneNumber to be treated as an object with fields, I want to simply serialize it as a string.

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• Custom types in OpenCL kernel

  - by Studer

  Is it possible to use custom types in OpenCL kernel like gmp types (mpz_t, mpq_t, …) ? To have something like that (this kernel doesn't build just because of #include <gmp.h>) : #include <gmp.h> __kernel square( __global mpz_t* input, __global mpz_t number, __global int* output, const unsigned int count) { int i = get_global_id(0); if(i < count) output[i] = mpz_divisible_p(number,input[i]); } Or maybe does OpenCL already have types that can handle large numbers ?

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