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  • How to get REALLY fast python over a simple loop

    - by totallymike
    I'm working on a spoj problem, INTEST. The goal is to specify the number of test cases (n) and a divisor (k), then feed your program n numbers. The program will accept each number on a newline of stdin and after receiving the nth number, will tell you how many were divisible by k. The only challenge in this problem is getting your code to be FAST because it k can be anything up to 10^7 and the test cases can be as high as 10^9. I'm trying to write it in python and having trouble speeding it up. Any ideas? import sys first_in = raw_input() thing = first_in.split() n = int(thing[0]) k = int(thing[1]) total = 0 i = 0 for line in sys.stdin: t = int(line) if t % k == 0: total += 1 print total

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  • Parsing a string representing a float *with an exponent* in Python

    - by Lucas
    Hi, I have a large file with numbers in the form of 6,52353753563E-7. So there's an exponent in that string. float() dies on this. While I could write custom code to pre-process the string into something float() can eat, I'm looking for the pythonic way of converting these into a float (something like a format string passed somewhere). I must say I'm surprised float() can't handle strings with such an exponent, this is pretty common stuff. I'm using python 2.6, but 3.1 is an option if need be.

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  • Django: ordering numerical value with order_by

    - by h3
    I'm in a situation where I must output a quite large list of objects by a CharField used to store street addresses. My problem is, that obviously the data is ordered by ASCII codes since it's a Charfield, with the predictable results .. it sort the numbers like this; 1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2, 20, 21.... Now the obvious step would be to change the Charfield the proper field type (IntegerField let's say), however it cannot work since some address might have apartments .. like "128A". I really don't know how I can order this properly ..

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  • gprof and execl() - is it possible?

    - by Chris
    Background: I have a game (an old-school-esque MUD) which I've been attempting to profile with gprof. The documentation of gprof (on Linux 2.6) states that The profiled program must call "exit"(2) or return normally for the profiling information to be saved in the gmon.out file. Now, if I kill the server with the shutdown command, the application "returns normally" (i.e., main() returns) and I get a gmon.out to analyze. However, it's far more common to reboot the server. The reboot command does the following: Writes usernames and socket FD numbers to disc. Makes a call to execl(). The new process looks for the stored data, picks up the FDs, and moves on. I see the following error on the command line, as the whole process fails: Profiling timer expired ./program Question: Is it possible to get a gmon.out file from the execl()-calling process? Perhaps some environmental parameter to execl(), or else perhaps a different, gprof-friendly, system call to achieve the same effect (beginning a new process while preserving file descriptors)?

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  • How to select a subset of results from a select statement

    - by Ankur
    I have a table that stores RDF triples: triples(triple_id, sub_id, pre_id, obj_id) The method (I need to write) will receive an array of numbers which correspond to pre_id values. I want to select all sub_id values that have a corresponding pre_id for all the pre_ids in the array that is passed in. E.g. if I had a single pre_id values passed in... lets call the value passed in preId, I would do: select sub_id from triples where pre_id=preId; However since I have mutliple pre_id values I want to keep iterating through the pre_id values and only keep the sub_id values corresponding to the "triples" records that have both. E.g. image there are five records: triples(1, 34,65,23) triples(2, 31,35,28) triples(3, 32,32,19) triples(4, 12,65,28) triples(5, 76,32,34) If I pass in an array of pre_id values [65,32] then I want to select the first, third, fourth and fifth records. What would I do for that?

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  • Pseudorandom Number Generation with Specific Non-Uniform Distributions

    - by carnun
    Hello all, I'm writing a program that simulates various random walks (with differing distributions). At each timestep, I need randomly generated, two dimensional step distances and angles from the distribution of the random walk. I'm hoping someone can check my understanding of how to generate these random numbers. As I understand it I can use Inverse Transform Sampling as follows: If f(x) is the pdf of our random walk that has a non-uniform distribution, and y is a random number from a uniform distribution. Then if we let f(x) = y and solve to find x then we have a random number from the non-uniform distribution. Is this a feasible solution?

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  • Separating merged array of arithmetic and geometric series

    - by user1814037
    My friend asked me an interseting question. Given an array of positive integers in increasing order. Seperate them in two series, an arithmetic sequence and geometric sequence. The given array is such that a solution do exist. The union of numbers of the two sequence must be the given array. Both series can have common elements i.e. series need not to be disjoint. The ratio of the geometric series can be fractional. Example: Given series : 2,4,6,8,10,12,25 AP: 2,4,6,8,10,12 GP: 4,10,25 I tried taking few examples but could not reach a general way. Even tried some graph implementation by introducing edges if they follow a particular sequence but could not reach solution.

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  • Reading Characher from Image

    - by Chinjoo
    I am working on an application which requires matching of numbers from a scanned image file to database entry and update the database with the match result. Say I have image- employee1.jpg. This image will have two two handwritten entries - Employee number and the amount to be paid to the employee. I have to read the employee number from the image and query the database for the that number, update the employee with the amount to be paid as got from the image. Both the employee number and amount to be paid are written inside two boxes at a specified place on the image. Is there any way to automate this. Basically I want a solution in .net using c#. I know this can be done using artificial neural networks. Any ideas would be much appreciated.

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  • Collection was modified; enumeration operation may not execute

    - by Rita
    I have the below code. I am trying to remove the record and it is throwing Exception when it is removing the Record. "Collection was modified; enumeration operation may not execute." Any ideas on how to get rid of the message. Appreciate your time. //validClaimControlNo has valid ClaimControl Numbers. List<string> validClaimControlNo = new List<string>(); int count = 0; foreach (List<Field> f in records) { foreach (Field fe in f) { if (i == 0) if (!(validClaimControlNo.Contains(fe.Value))) { //if this claim is not in the Valid list, Remove that Record records.RemoveAt(count); } i++; } i = 0; count++; }

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  • How to insert into std::map.

    - by Knowing me knowing you
    In code below: map<string,vector<int>> create(ifstream& in, const vector<string>& vec) { /*holds string and line numbers into which each string appears*/ typedef map<string,vector<int>> myMap; typedef vector<string>::const_iterator const_iter; myMap result; string tmp; unsigned int lineCounter = 0; while(std::getline(in,tmp)) { const_iter beg = vec.begin(); const_iter end = vec.end(); while (beg < end) { if ( tmp.find(*beg) != string::npos) { result[*beg].push_back(lineCounter);//THIS IS THE LINE I'M ASKING FOR } ++beg; } ++lineCounter; } return result; } How should I do it (check line commented in code) if I want to use insert method of map instead of using operator[]? Thank you.

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  • VBA long overflow

    - by HK_CH
    Hi I am trying to do some maths with my VBA excel (prime factorization) and I am hitting the limit of the long data type (runtime error 6 Overflow). Is there any way to get around this and still stay within VBA? (I am aware that the obvious one would be to use another more appropriate programming language) Thanks for help in advance! Thank you, it works in so far that I am able to get the big numbers into the variables now. However when I try to apply the MOD function (bignumber MOD 2 for example) it still fails with error message runtime error 6 Overflow.

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  • Which database should I use for best performance

    - by _simon_
    Hello, I am working in Visual Studio 2005, .NET 2.0. I need to write an application, which listens on COM port and saves incoming data to a database. Main feature: save incoming data (series of 13-digits numbers), if this number allready exists, then mark it as double. For example, there could be these records in database: 0000000000001 OK 0000000000002 OK 0000000000002 Double 0000000000003 OK 0000000000004 OK I could use SQL database, but I don't know if it is fast enough... Database should be able to store up to 10.000.000 records and write up to 100 records per minute (so it needs to check 100 times per minute if this record allready exists). Which database should I use? Maybe the whole database would need to be in RAM. Where could I learn more about this? Thanks

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  • How to prevent users from typing incorrect inputs ?

    - by ZaZu
    Hello, I want the program to loop a scan function if the user types anything else other than numbers.. My code is : do{ printf("Enter rows\n"); scanf("%d",&row); }while(row>='a' && row<='z'); but this code doesnt work .. I keep getting an error when typing in a letter. I tried manipulating around it and the whole thing loops infinitely ... What am I doing wrong ? Please help thanks !

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  • I can't understand GroupJoin where i will need it in database relationships.

    - by Freshblood
    Hello Everybody I am thinking 5-6 hours to understand something about GroupJoin. I am talking about query with linq for Database tables.I understand what Join and GroupJoin does but I really couldn't understand where i will need it.I feel that Join does all what i will need but if there is something which Join can't without GroupJoin so i feel that situation is meaningless or useless. For example: Persons table in relation with Phones and Phones table hold foreign keys of Persons and one person can have one more phone number.If we want to brings all persons who has phone numbers and who hasn't too so we will need GroupJOin but what for we will need this query ? Can u give me good reason , example or explenation for using GroupJoin ?

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  • Find a common element within N arrays

    - by kunjaan
    If I have N arrays, what is the best(Time complexity. Space is not important) way to find the common elements. You could just find 1 element and stop. Edit: The elements are all Numbers. Edit: These are unsorted. Please do not sort and scan. This is not a homework problem. Somebody asked me this question a long time ago. He was using a hash to solve the problem. I was thinking if SO has solved similar problems.

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  • How to check input text into web form? java script

    - by butteff
    how to check input text before POST operation? it must be numbers only <form method="post" action="credit.php"> ????? ???????: <input type="text" name="sum"> <br /> ?????? ?????: <input type="text" name="pv"> <br /> ????: <input type="text" name="srok"> <br /> ?????????? ??????: <input type="text" name="percent"> <br /> <input type="submit"> </form> sorry for my bad english.

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  • Strange hex formatting in NSString

    - by pseudopeach
    Try this: unsigned long long int N; = 23229877463LL; NSString* s = [NSString stringWithFormat:@"dec:%qi, hex:%qX",N,N]; NSLog(@"output: %@",s); output: dec:23229877460, hex:689BCCD400000005 What's up with the 00000005??? In mySQL, hex(23229877460) = 5689BCCD4. Also, every other language seems to do this correctly. A 16 digit long hex is like 4 gazillion (16^16), right? How can I get objective-c to format hex numbers that other languages can understand?

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  • Write set of integers to std::ofstream and be able to read them back

    - by bndu
    Hello, I need to write a bunch of unsigned integers to std::ofstream in binary mode: std::ofstream f; f.open("some path", std::ios::out | std::ios::binary); // some loop { unsigned int k = get_k(); // may product numbers from 0 to 65535 f << k; } f.close(); They are written to the output file "as is" w/o any delimiter. So when I'm trying to read them back (expecting to get what I wrote) using std::ifstream I get very strange values. What I'm doing wrong? Or I should to put ' ' (space) to the stream after any added number to separate them? Thanks.

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  • How to introduce multi-column constraint with JPA annotations?

    - by plouh
    I am trying to introduce a multi-key constraint on a JPA-mapped entity: public class InventoryItem { @Id private Long id; @Version private Long version; @ManyToOne @JoinColumn("productId") private Product product; @Column(nullable=false); private long serial; } Basically (product, serial) pair should be unique, but I only found a way to say that serial should be unique. This obviously isn't a good idea since different products might have same serial numbers. Is there a way to generate this constraint via JPA or am I forced to manually create it to DB?

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  • JavaScript: how to use data but to hide it so as it cannot be reused

    - by loukote
    Hi all. I've some data that i'd like to publish just on one website, ie. it should not be reused on other websites. The data is a set of numbers that change every day, our journalists work to get hard gather it. Is there any way to hide, crypt, etc. the data in a way that it cannot be reused by others? But to show it in a graph in the same time? I found the ASCII to HEX tool that could be used for (http://utenti.multimania.it/ascii2hex/). I wonder if you can suggest other ways. (Even if I have to completely change the strategy.) Many thanks!

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  • how do I check if a c++ string is an int?

    - by user342231
    when I use getline, I would input a bunch of strings or numbers, but I only want the while loop to output the "word" if it is not a number. so is there any way to check if "word" is a number or not, I know I could use atoi() for c-strings but how about for strings of the string class int main () { stringstream ss (stringstream::in | stringstream::out); string word; string str; getline(cin,str); ss<<str; while(ss>>word) { //if( ) cout<<word<<endl; } }

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  • What is the cost of memory access?

    - by Jurily
    We like to think that a memory access is fast and constant, but on modern architectures/OSes, that's not necessarily true. Consider the following C code: int i = 34; int *p = &i; // do something that may or may not involve i and p {...} // 3 days later: *p = 643; What is the estimated cost of this last assignment in CPU instructions, if i is in L1 cache, i is in L2 cache, i is in L3 cache, i is in RAM proper, i is paged out to an SSD disk, i is paged out to a traditional disk? Where else can i be? Of course the numbers are not absolute, but I'm only interested in orders of magnitude. I tried searching the webs, but Google did not bless me this time.

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  • Trouble converting string/character to byte in lisp

    - by WanderingPhd
    I've some data that I'm reading in using read-line and I want to convert it into a byte-array. babel:string-to-octet works for the most part except when the character\byte is larger (above 200) in which case it returns two numbers. As an example, if the character is ú using babel:string-to-octet returns (195 185) instead of 250 which is what I'm looking for. I tried a number of encodings in babel but none of them seem to work. If I use read-byte or read-sequence it does read in 250. But for reasons of backward compatibility, I'm left with using read-line and I would like to know if there is something I'm missing when using babel:string-to-octet to convert ú to 250. I'm using ccl 1.8 btw.

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  • Is there a way to get the expression in a string in vb.net

    - by Jim Thio
    LogEvents(System.Text.Encoding.UTF8.GetString(queryPlaces.ToBson)) I want to be able to output not just the content of System.Text.Encoding.UTF8.GetString(queryPlaces.ToBson) but also the actual string of System.Text.Encoding.UTF8.GetString(queryPlaces.ToBson) itself, perhaps with line numbers and file names. I know that I can do this easily with objective-c. How can I do that with .net? I've heard that that's what reflextion is for. But how? There is no macro in vb.net right?

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  • c++ - QListWidget

    - by user1889459
    I created a working QListWidget with multiple items, but I can't figure out how to make it user-friendly. It looks like this: 1000 1001 1002 ... But I want it to look like this, where firt 4 numbers have a meaning, while all the rest info is just for user. 1000 Name LastName and some other helpful info 1001 tom jeff smallville 1002 ming vase, 1992 ... For example, this line fotoId = ui->devices->currentItem()->text().toInt(); should give me same result in both cases.

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