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  • How to store and collect data for mining such information as most viewed for last 24 hours, last 7 d

    - by Kirzilla
    Hello, Let's imagine that we have high traffic project (a tube site) which should provide sorting using this options (NOT IN REAL TIME). Number of videos is about 200K and all information about videos is stored in MySQL. Number of daily video views is about 1.5KK. As instruments we have Hard Disk Drive (text files), MySQL, Redis. Views top viewed top viewed last 24 hours top viewed last 7 days top viewed last 30 days top rated last 365 days How should I store such information? The first idea is to log all visits to text files (single file per hour, for example visits_20080101_00.log). At the beginning of each hour calculate views per video for previous hour and insert this information into MySQL. Then recalculate totals (for last 24 hours) and update statistics in tables. At the beginning of every day we have to do the same but recalculate for last 7 days, last 30 days, last 365 days. This method seems to be very poor for me because we have to store information about last 365 days for each video to make correct calculations. Is there any other good methods? Probably, we have to choose another instruments for this? Thank you.

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  • Convert bit vector (array of booleans) to an integer, and integer to bit vector, in Java.

    - by dreeves
    What's the best way to unstub the following functions? // Convert a bit-vector to an integer. int bitvec2int(boolean[] b) { [CODE HERE] } // Convert an integer x to an n-element bit-vector. boolean[] int2bitvec(int x, int n) { [CODE HERE] } Or is there a better way to do that sort of thing than passing boolean arrays around? This comes up in an Android app where we need an array of 20 booleans to persist and the easiest way to do that is to write an integer or string to the key-value store. I'll post the way we (Bee and I) wrote the above as an answer. Thanks!

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  • C Population Count of unsigned 64-bit integer with a maximum value of 15

    - by BitTwiddler1011
    I use a population count (hamming weight) function intensively in a windows c application and have to optimize it as much as possible in order to boost performance. More than half the cases where I use the function I only need to know the value to a maximum of 15. The software will run on a wide range of processors, both old and new. I already make use of the POPCNT instruction when Intel's SSE4.2 or AMD's SSE4a is present, but would like to optimize the software implementation (used as a fall back if no SSE4 is present) as much as possible. Currently I have the following software implementation of the function: inline int population_count64(unsigned __int64 w) { w -= (w 1) & 0x5555555555555555ULL; w = (w & 0x3333333333333333ULL) + ((w 2) & 0x3333333333333333ULL); w = (w + (w 4)) & 0x0f0f0f0f0f0f0f0fULL; return int(w * 0x0101010101010101ULL) 56; } So to summarize: (1) I would like to know if it is possible to optimize this for the case when I only want to know the value to a maximum of 15. (2) Is there a faster software implementation (for both Intel and AMD CPU's) than the function above?

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  • Is it compulsory to learn about Data Structures if you want to be a Java/C++ programmer ?

    - by happysoul
    So do I like really need to learn about them ? Isn't there an interesting way to learn about stacks, linked lists, heaps ,etc ? I found it a boring subject. **While posting this question it showed some warning.Am I not allowed to post such a question ? Admins please clarify and I will delete it :/ Warning :: The question you're asking appears subjective and is likely to be closed.

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  • Most performant way to check how many objects are referenced by an to-many relationship in Core Data

    - by dontWatchMyProfile
    Lets say I have an employees relationship in an Company entity, and it's to-many. And they're really many. Apple in 100 years, with 1.258.500.073 employees. Could I simply do something like NSInteger numEmployees = [apple.employees count]; without firing 1.258.500.073 faults? (Well, in 100 years, the iPhone will easily handle so many objects, for sure...but anyways)

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  • How does the stream manipulators work?

    - by Narek
    It is well known that the user can define stream manipulators like this: ostream& tab(ostream & output) { return output<< '\t'; } And this can be used in main() like this: cout<<'a'<<tab<<'b'<<'c'<<endl; Please explain me how does this all work? If operator<< assumes as a second parameter a pointer to the function that takes and returns ostream &, then please explain my why it is necessary? What would be wrong if the function does not take and return ostream & but it was void instead of ostream &? Also it is interesting why “dec”, “hex” manipulators take effect until I don’t change between them, but user defined manipulators should be always used in order to take effect for each streaming?

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  • ruby enclose selected whole words in brackets

    - by astropanic
    @string = "Sometimes some stupid people say some stupid words" @string.enclose_in_brackets("some") # => "Sometimes {some} stupid people say {some} stupid words" How should the method enclose_in_brackets look ? Please keep in mind, I want only enclose whole words, (I don't want "{Some}times {some} stupid....", the "sometimes" word should be left unchanged

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  • [VB.Net] String Manipultation - Get String between two other Strings?

    - by Ben
    I have a large piece of text in which there is something simular to this: !#_KT_#!COMMANDHERE!#_KT_#! I want, in VB.Net, to get the 'COMMANDHERE' part of the string, how would I go about doing this? I have this so far: Dim temp As String = WebBrowser1.Document.Body.ToString Dim startIndex As Integer = temp.IndexOf("!#__KT__#!") + 1 Dim endIndex As Integer = temp.IndexOf("!#__KT__#!", startIndex) Dim extraction As String = temp.Substring(startIndex, endIndex - startIndex).Trim TextBox1.Text = extraction However this only removes the LAST string eg: #_KT_#! COMMAND. Any help is appreciated!

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  • bit ordering and endianess

    - by Neeraj
    I am reading a file byte-by-byte. Say for example i have this byte: 0x41 (0100 0001) represented in hex. Now, I want the first three bits of this byte, i.e (010). I can use bitwise logic to extract the first three bits, but my question is will the first three bits be independent of endianess of the machine.(i.e they can't be 001)? Thanks,

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  • How to optimize this simple function which translates input bits into words?

    - by psihodelia
    I have written a function which reads an input buffer of bytes and produces an output buffer of words where every word can be either 0x0081 for each ON bit of the input buffer or 0x007F for each OFF bit. The length of the input buffer is given. Both arrays have enough physical place. I also have about 2Kbyte free RAM which I can use for lookup tables or so. Now, I found that this function is my bottleneck in a real time application. It will be called very frequently. Can you please suggest a way how to optimize this function? I see one possibility could be to use only one buffer and do in-place substitution. void inline BitsToWords(int8 *pc_BufIn, int16 *pw_BufOut, int32 BufInLen) { int32 i,j,z=0; for(i=0; i<BufInLen; i++) { for(j=0; j<8; j++, z++) { pw_BufOut[z] = ( ((pc_BufIn[i] >> (7-j))&0x01) == 1? 0x0081: 0x007f ); } } } Please do not offer any compiler specific or CPU/Hardware specific optimization, because it is a multi-platform project.

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  • How to evaluate the string in ruby if the string contains ruby command?

    - by Arun
    In my case, I was storing the sql query in my database as text. I am showing you one record which is present in my database Query.all :id => 1, :sql => "select * from user where id = #{params[:id]}" str = Query.first Now 'str' has value "select * from user where id = #{params[:id]}" Here, I want to parsed the string like If my params[:id] is 1 then "select * from user where id = 1" I used eval(str). Is this correct?

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  • c++ creating ambigram from string

    - by mike_hornbeck
    I have a task to implement "void makeAmbigram(char*)" that will print on screen ambigram of latin string or return something like 'ambigram not possible'. Guess it's just about checking if string contains only of SNOXZHI and printing string backwards. Or am I wrong ? I'm a complete noob when dealing with cpp so that's what I've created : #include <iostream> using namespace std; char[]words; char[]reversed; char[] ret_str(char* s) { if(*s != '\0') ret_str(s+1); return s; } void makeAmbigram(char* c) { /* finding chars XIHNOZS and printing ambigram */ } int main() { cin>>words; reversed = ret_str(words); makeAmbigram(reversed); return 0; } I can reverse string but how to check if my reversed string contains only needed chars ? I've found some function but it's hard or even imposible to implement it for greater amount of chars : http://www.java2s.com/Code/C/String/Findcharacterinstringhowtousestrchr.htm

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  • Searching for online database software/cms

    - by ButterdBread
    I am searching for a software or CMS that manages and displays large online databases, as some kind of frontend to MySQL or any other database. It should be accessible through the browser, be as secure as possible (offering login). The data I'd like to store would be personal information such as name, adress and birthday - also I'd need to be able to add custom fields as well. Also forms and the possibility to download the data in an excel? table would be great. PHPmyadmin is not an option, it should be similar to a CRM but more closely adapted to managing database tables, searching for entries and filtering data. It should be possible to have many user accounts with different rights, with each of them being able to acces certain parts of the data and entering own data. Is there something out there, that might get close to what I imagine? I appreciate any help!

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  • Set hidden form field values with JavaScript but request still empty

    - by tigerstyle
    HI volks, I try to set some hidden form field values with an onclick event. Ok, after I did something like this: document.getElementById('hidden_field').value = 123; I can output the value with the firebug console by entering this: alert(document.getElementById('hidden_field').value); So the values are definitely set. But now when I submit the form, the hidden field values are still empty. Do you have any idea whats going wrong? Thx for your answers.

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  • How to Concatenate 2 C strings, without overwriting any terminating Null characters?

    - by Ben313
    Hello, I am trying to set up a list of file names for a parameter to SHFileOperation. I want to be able to concatenate a file name onto the char array, but i dont want to get rid of the terminating character. for example, I want this: C:\...\0E:\...\0F:\...\0\0 when i use strcat(), it overwrites the null, so it looks like C:\...E:\...F:\...0\ Is there any easy way to do this? or am i going to have to code a new strcat for myself?

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  • Overwriting a range of bits in an integer in a generic way

    - by porgarmingduod
    Given two integers X and Y, I want to overwrite bits at position P to P+N. Example: int x = 0xAAAA; // 0b1010101010101010 int y = 0x0C30; // 0b0000110000110000 int result = 0xAC3A; // 0b1010110000111010 Does this procedure have a name? If I have masks, the operation is easy enough: int mask_x = 0xF00F; // 0b1111000000001111 int mask_y = 0x0FF0; // 0b0000111111110000 int result = (x & mask_x) | (y & mask_y); What I can't quite figure out is how to write it in a generic way, such as in the following generic C++ function: template<typename IntType> IntType OverwriteBits(IntType dst, IntType src, int pos, int len) { // If: // dst = 0xAAAA; // 0b1010101010101010 // src = 0x0C30; // 0b0000110000110000 // pos = 4 ^ // len = 8 ^------- // Then: // result = 0xAC3A; // 0b1010110000111010 } The problem is that I cannot figure out how to make the masks properly when all the variables, including the width of the integer, is variable. Does anyone know how to write the above function properly?

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  • clever way to conditionally split this string?

    - by sprugman
    I've got a string that could be in one of two forms: prefix=key=value (which could have any characters, including '=') or key=value So I need to split it either on the first or second equals sign, based on a boolean that gets set elsewhere. I'm doing this: if ($split_on_second) { $parts = explode('=', $str, 3); $key = $parts[0] . '=' . $parts[1]; $val = $parts[2]; } else { $parts = explode('=', $str, 2); $key = $parts[0]; $val = $parts[1]; } Which should work, but feels inelegant. Got any better ideas in php? (I imagine there's a regex-ninja way to do it, but I'm not a regex-ninja.;-)

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  • string in c++,question

    - by user189364
    Hi, I created a program in C++ that remove commas (') from a given integer. i.e. 2,00,00 would return 20000. I am not using any new space. Here is the program i created void removeCommas(string& str1,int len) { int j=0; for(int i=0;i<len;i++) { if(str1[i] == ',') continue; else { str1[j] =str1[i]; j++; } } str1[j] = '\0'; } void main() { string str1; getline(cin,str1); int i = str1.length(); removeCommas(str1,i); cout<<"the new string "<<str1<<endl; } Here is the result i get : Input : 2,000,00 String length =8 Output = 200000 0 Length = 8 My question is that why does it show the length has 8 in output and shows the rest of string when i did put a null character. It should show output as 200000 and length has 6.

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  • servlet ArrayList and HashMap problem witch result

    - by nonameplum
    Hi, I have that code List<Map<String, Object>> data = new ArrayList<Map<String, Object>>(); Map<String, Object> item = new HashMap<String, Object>(); data.clear(); item.clear(); int i = 0; while (i < 5){    item.put("id", i);    i++;    out.println("id: " + item.get("id"));    out.println("--------------------------");    data.add(item); } for(i=0 ; i<5 ; i++){    out.println("print data[" + i + "]" + data.get(i)); } Result of that is: id: 0 -------------------------- id: 1 -------------------------- id: 2 -------------------------- id: 3 -------------------------- id: 4 -------------------------- print data[0]{id=4} print data[1]{id=4} print data[2]{id=4} print data[3]{id=4} print data[4]{id=4} Why only last element is stored?

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