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  • how to init binary buffer in python

    - by ace
    so, I read from DB binary field i.e. 'field1' to var Buf1, and then do something like: unpack_from('I', Buf1, 0) so, all is ok. but question is how can I ini Buf1 without going to DB? I can get value from DB manually and init my var statically, but how? in DB field 'field1' I see something like '0x7B0500000100000064000000B80100006'. and how can I init valid binary buffer from it?

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  • VB6: Slow Binary Write?

    - by Tom the Junglist
    Wondering why a particular binary write operation in VB is so slow. The function reads a Byte array from memory and dumps it into a file like this: Open Destination For Binary Access Write As #1 Dim startP, endP As Long startP = BinaryStart endP = UBound(ReadBuf) - 1 Dim i as Integer For i = startP To endP DoEvents Put #1, (i - BinaryStart) + 1, ReadBuf(i) Next Close #1 For two megabytes on a slower system, this can take up to a minute. Can anyone tell me why this is so slow?

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  • PHP - post data ends when '&' is in data.

    - by Phil Jackson
    Hi all, im posting data using jquery/ajax and PHP at the backend. Problem being, when I input something like 'Jack & Jill went up the hill' im only recieving 'Jack' when it gets to the backend. I have thrown an error at the frontend before that data is sent which alerts 'Jack & Jill went up the hill'. When I put die(print_r($_POST)); at the very top of my index page im only getting [key] => Jack how can I be loosing the data? I thought It may have been my filter; <?php function filter( $data ) { $data = trim( htmlentities( strip_tags( mb_convert_encoding( $data, 'HTML-ENTITIES', "UTF-8") ) ) ); if ( get_magic_quotes_gpc() ) { $data = stripslashes( $data ); } //$data = mysql_real_escape_string( $data ); return $data; } echo "<xmp>" . filter("you & me") . "</xmp>"; ?> but that returns fine in the test above you &amp; me which is in place after I added die(print_r($_POST));. Can anyone think of how and why this is happening? Any help much appreciated. Regards, Phil.

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  • Is this the right strategy to convert an in-level order binary tree to a doubly linked list?

    - by Ankit Soni
    So I recently came across this question - Make a function that converts a in-level-order binary tree into a doubly linked list. Apparently, it's a common interview question. This is the strategy I had - Simply do a pre-order traversal of the tree, and instead of returning a node, return a list of nodes, in the order in which you traverse them. i.e return a list, and append the current node to the list at each point. For the base case, return the node itself when you are at a leaf. so you would say left = recursive_function(node.left) right = recursive_function(node.right) return(left.append(node.data)).append(right);` Is this the right approach?

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  • How to have operations with character/items in binary with concrete operations?

    - by Piperoman
    I have the next problem. A item can have a lot of states: NORMAL = 0000000 DRY = 0000001 HOT = 0000010 BURNING = 0000100 WET = 0001000 COLD = 0010000 FROZEN = 0100000 POISONED= 1000000 A item can have some states at same time but not all of them Is impossible to be dry and wet at same time. If you COLD a WET item, it turns into FROZEN. If you HOT a WET item, it turns into NORMAL A item can be BURNING and POISON Etc. I have tried to set binary flags to states, and use AND to combine different states, checking before if it is possible or not to do it, or change to another status. Does there exist a concrete approach to solve this problem efficiently without having an interminable switch that checks every state with every new state? It is relatively easy to check 2 different states, but if there exists a third state it is not trivial to do.

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  • How to have operations with character/items on binary with concrete operations on C++?

    - by Piperoman
    I have the next problem. A item can have a lot of states: NORMAL = 0000000 DRY = 0000001 HOT = 0000010 BURNING = 0000100 WET = 0001000 COLD = 0010000 FROZEN = 0100000 POISONED= 1000000 A item can have some states at same time but not all of them Is impossible to be dry and wet at same time. If you COLD a WET item, it turns into FROZEN. If you HOT a WET item, it turns into NORMAL A item can be BURNING and POISON Etc. I have tried to set binary flags to states, and use AND to combine different states, checking before if it is possible or not to do it, or change to another status. Does there exist a concrete approach to solve this problem efficiently without having an interminable switch that checks every state with every new state? It is relatively easy to check 2 different states, but if there exists a third state it is not trivial to do.

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  • How to had operation with character/items on binary with concrete operations on C++?

    - by Piperoman
    I have the next problem. A item can had a lot of states: NORMAL = 0000000 DRY = 0000001 HOT = 0000010 BURNING = 0000100 WET = 0001000 COLD = 0010000 FROZEN = 0100000 POISONED= 1000000 A item can had some states at same time but not all of them Is impossible to be dry and wet at same time. If you COLD a WET item, it turns into FROZEN. If you HOT a WET item, it turns into NORMAL A item can be BURNING and POISON Etc. I have try to set binary flags to states, and use AND to set operation to combine different states, checking before if is possible or not to do it, or change to another status. Exist a concrete patron to solve this problem efficiently without had a interminable switch that check every states with everynew states? It is relative easy to check 2 different states, but if exist a third state it is not trivial to do.

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  • What web oriented language would work best with binary data?

    - by Qqwy
    I want to create a service where people can upload files. However, since file storage costs money, I want to compress the files so they take less space. I would want to write my own compression algorithm, however, PHP doesn't have good ways to handle binary data (which is needed for many compression algorithms). So I wondered, what would be a better language to create such a website in? I have knowledge of PHP (and Javascript, HTML and CSS) but no experience with other things like Ruby, Perl, Python, and other web development languages.

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  • improving conversions to binary and back in C#

    - by Saad Imran.
    I'm trying to write a general purpose socket server for a game I'm working on. I know I could very well use already built servers like SmartFox and Photon, but I wan't to go through the pain of creating one myself for learning purposes. I've come up with a BSON inspired protocol to convert the the basic data types, their arrays, and a special GSObject to binary and arrange them in a way so that it can be put back together into object form on the client end. At the core, the conversion methods utilize the .Net BitConverter class to convert the basic data types to binary. Anyways, the problem is performance, if I loop 50,000 times and convert my GSObject to binary each time it takes about 5500ms (the resulting byte[] is just 192 bytes per conversion). I think think this would be way too slow for an MMO that sends 5-10 position updates per second with a 1000 concurrent users. Yes, I know it's unlikely that a game will have a 1000 users on at the same time, but like I said earlier this is supposed to be a learning process for me, I want to go out of my way and build something that scales well and can handle at least a few thousand users. So yea, if anyone's aware of other conversion techniques or sees where I'm loosing performance I would appreciate the help. GSBitConverter.cs This is the main conversion class, it adds extension methods to main datatypes to convert to the binary format. It uses the BitConverter class to convert the base types. I've shown only the code to convert integer and integer arrays, but the rest of the method are pretty much replicas of those two, they just overload the type. public static class GSBitConverter { public static byte[] ToGSBinary(this short value) { return BitConverter.GetBytes(value); } public static byte[] ToGSBinary(this IEnumerable<short> value) { List<byte> bytes = new List<byte>(); short length = (short)value.Count(); bytes.AddRange(length.ToGSBinary()); for (int i = 0; i < length; i++) bytes.AddRange(value.ElementAt(i).ToGSBinary()); return bytes.ToArray(); } public static byte[] ToGSBinary(this bool value); public static byte[] ToGSBinary(this IEnumerable<bool> value); public static byte[] ToGSBinary(this IEnumerable<byte> value); public static byte[] ToGSBinary(this int value); public static byte[] ToGSBinary(this IEnumerable<int> value); public static byte[] ToGSBinary(this long value); public static byte[] ToGSBinary(this IEnumerable<long> value); public static byte[] ToGSBinary(this float value); public static byte[] ToGSBinary(this IEnumerable<float> value); public static byte[] ToGSBinary(this double value); public static byte[] ToGSBinary(this IEnumerable<double> value); public static byte[] ToGSBinary(this string value); public static byte[] ToGSBinary(this IEnumerable<string> value); public static string GetHexDump(this IEnumerable<byte> value); } Program.cs Here's the the object that I'm converting to binary in a loop. class Program { static void Main(string[] args) { GSObject obj = new GSObject(); obj.AttachShort("smallInt", 15); obj.AttachInt("medInt", 120700); obj.AttachLong("bigInt", 10900800700); obj.AttachDouble("doubleVal", Math.PI); obj.AttachStringArray("muppetNames", new string[] { "Kermit", "Fozzy", "Piggy", "Animal", "Gonzo" }); GSObject apple = new GSObject(); apple.AttachString("name", "Apple"); apple.AttachString("color", "red"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)1.5); GSObject lemon = new GSObject(); apple.AttachString("name", "Lemon"); apple.AttachString("color", "yellow"); apple.AttachBool("inStock", false); apple.AttachFloat("price", (float)0.8); GSObject apricoat = new GSObject(); apple.AttachString("name", "Apricoat"); apple.AttachString("color", "orange"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)1.9); GSObject kiwi = new GSObject(); apple.AttachString("name", "Kiwi"); apple.AttachString("color", "green"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)2.3); GSArray fruits = new GSArray(); fruits.AddGSObject(apple); fruits.AddGSObject(lemon); fruits.AddGSObject(apricoat); fruits.AddGSObject(kiwi); obj.AttachGSArray("fruits", fruits); Stopwatch w1 = Stopwatch.StartNew(); for (int i = 0; i < 50000; i++) { byte[] b = obj.ToGSBinary(); } w1.Stop(); Console.WriteLine(BitConverter.IsLittleEndian ? "Little Endian" : "Big Endian"); Console.WriteLine(w1.ElapsedMilliseconds + "ms"); } Here's the code for some of my other classes that are used in the code above. Most of it is repetitive. GSObject GSArray GSWrappedObject

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  • Binary files printing and desired precision

    - by yCalleecharan
    Hi, I'm printing a variable say z1 which is a 1-D array containing floating point numbers to a text file so that I can import into Matlab or GNUPlot for plotting. I've heard that binary files (.dat) are smaller than .txt files. The definition that I currently use for printing to a .txt file is: void create_out_file(const char *file_name, const long double *z1, size_t z_size){ FILE *out; size_t i; if((out = _fsopen(file_name, "w+", _SH_DENYWR)) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < z_size; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } I have three questions: Are binary files really more compact than text files?; If yes, I would like to know how to modify the above code so that I can print the values of the array z1 to a binary file. I've read that fprintf has to be replaced with fwrite. My output file say dodo.dat should contain the values of array z1 with one floating number per line. I have %.16Le up in my code but I think that %.15Le is right as I have 15 precision digits with long double. I have put a dot (.) in the width position as I believe that this allows expansion to an arbitrary field to hold the desired number. Am I right? As an example with %.16Le, I can have an output like 1.0047914240730432e-002 which gives me 16 precision digits and the width of the field has the right width to display the number correctly. Is placing a dot (.) in the width position instead of a width value a good practice? Thanks a lot...

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  • Using recursion to to trim a binary tree based on a given min and max value

    - by Justin
    As the title says, I have to trim a binary tree based on a given min and max value. Each node stores a value, and a left/right node. I may define private helper methods to solve this problem, but otherwise I may not call any other methods of the class nor create any data structures such as arrays, lists, etc. An example would look like this: overallRoot _____[50]____________________ / \ __________[38] _______________[90] / \ / _[14] [42] [54]_____ / \ \ [8] [20] [72] \ / \ [26] [61] [83] trim(52, 65); should return: overallRoot [54] \ [61] My attempted solution has three methods: public void trim(int min, int max) { rootFinder(overallRoot, min, max); } First recursive method finds the new root perfectly. private void rootFinder(IntTreeNode node, int min, int max) { if (node == null) return; if (overallRoot.data < min) { node = overallRoot = node.right; rootFinder(node, min, max); } else if (overallRoot.data > max) { node = overallRoot = node.left; rootFinder(node, min, max); } else cutter(overallRoot, min, max); } This second method should eliminate any further nodes not within the min/max, but it doesn't work as I would hope. private void cutter(IntTreeNode node, int min, int max) { if (node == null) return; if (node.data <= min) { node.left = null; } if (node.data >= max) { node.right = null; } if (node.data < min) { node = node.right; } if (node.data > max) { node = node.left; } cutter(node.left, min, max); cutter(node.right, min, max); } This returns: overallRoot [54]_____ \ [72] / [61] Any help is appreciated. Feel free to ask for further explanation as needed.

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  • how to send binary data within an xml string

    - by daemonkid
    I want to send a binary file to .net c# component in the following xml format <BinaryFileString fileType='pdf'> <!--binary file data string here--> </BinaryFileString> In the component that is called I will use the above xml string and convert the binary string recieved within the BinaryFileString tag, into a file as specified by the filetype='' attribute. The file type could be doc/pdf/xls/rtf I have the code in the calling application to get out the bytes from the file to be sent. How do I prepare it to be sent with xml tags wrapped around it? I want the application to send out a string to the component and not a byte stream. This is because there is no way I can decipher the file type [pdf/doc/xls] by just looking at the byte stream. Hence the xml string with the filetype attribute. Any ideas on this? method for extracting Bytes below FileStream fs = new FileStream(_filePath, FileMode.Open, FileAccess.Read); using (Stream input = fs) { byte[] buffer = new byte[8192]; int bytesRead; while ((bytesRead = input.Read(buffer, 0, buffer.Length)) > 0) { } } return buffer; Thanks.

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  • Boost Binary Endian parser not working?

    - by Hai
    I am studying how to use boost spirit Qi binary endian parser. I write a small test parser program according to here and basics examples, but it doesn't work proper. It gave me the msg:"Error:no match". Here is my code. #include "boost/spirit/include/qi.hpp" #include "boost/spirit/include/phoenix_core.hpp" #include "boost/spirit/include/phoenix_operator.hpp" #include "boost/spirit/include/qi_binary.hpp" // parsing binary data in various endianness template '<'typename P, typename T void binary_parser( char const* input, P const& endian_word_type, T& voxel, bool full_match = true) { using boost::spirit::qi::parse; char const* f(input); char const* l(f + strlen(f)); bool result1 = parse(f,l,endian_word_type,voxel); bool result2 =((!full_match) || (f ==l)); if ( result1 && result2) { //doing nothing, parsing data is pass to voxel alreay } else { std::cerr << "Error: not match!!" << std::endl; exit(1); } } typedef boost::uint16_t bs_int16; typedef boost::uint32_t bs_int32; int main ( int argc, char *argv[] ) { namespace qi = boost::spirit::qi; namespace ascii = boost::spirit::ascii; using qi::big_word; using qi::big_dword; boost::uint32_t ui; float uf; binary_parser("\x01\x02\x03\x04",big_word,ui); assert(ui=0x01020304); binary_parser("\x01\x02\x03\x04",big_word,uf); assert(uf=0x01020304); return 0; }' I almost copy the example, but why this binary parser doesn't work. I use Mac OS 10.5.8 and gcc 4.01 compiler.

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  • SQL Developer Debugging, Watches, Smart Data, & Data

    - by thatjeffsmith
    After presenting the SQL Developer PL/SQL debugger for about an hour yesterday at KScope12 in San Antonio, my boss came up and asked, “Now, would you really want to know what the Smart Data panel does?” Apparently I had ‘made up’ my own story about what that panel’s intent is based on my experience with it. Not good Jeff, not good. It was a very small point of my presentation, but I probably should have read the docs. The Smart Data tab displays information about variables, using your Debugger: Smart Data preferences. You can also specify these preferences by right-clicking in the Smart Data window and selecting Preferences. Debugger Smart Data Preferences, control number of variables to display The Smart Data panel auto-inspects the last X accessed variables. So if you have a program with 26 variables, instead of showing you all 26, it will just show you the last two variables that were referenced in your program. If you were to click on the ‘Data’ debug panel, you’ll see EVERYTHING. And if you only want to see a very specific set of values, then you should use Watches. The Smart Data Panel As I step through the code, the variables being tracked change as they are referenced. Only the most recent ones display. This is controlled by the ‘Maximum Locations to Remember’ preference. Step through the code, see the latest variables accessed The Data Panel All variables are displayed. Might be information overload on large PL/SQL programs where you have many dozens or even hundreds of variables to track. Shows everything all the time Watches Watches are added manually and only show what you ask for. Data on Demand – add a watch to track a specific variable Remember, you can interact with your data If you want to do more than just watch, you can mouse-right on a data element, and change the value of the variable as the program is running. This is one of the primary benefits to debugging over using DBMS_OUTPUT to track what’s happening in your program. Change the values while the program is running to test your ‘What if?’ scenarios

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  • SQL – Biggest Concerns in a Data-Driven World

    - by Pinal Dave
    The ongoing chaos over Government Agency’s snooping has ignited a heated debate on privacy of personal data and its use by government and/or other institutions. It has created a feeling of disapproval and distrust among users. This incident proves to be a lesson for companies that are looking to leverage their business using a data driven approach. According to analysts, the goal of gathering personal information should be to deliver benefits to both the parties – the user as well as the data collector(government or business). Using data the right way is crucial, and companies need to deploy the right software applications and systems to ensure that their efforts are well-directed. However, there are various issues plaguing analysts regarding available software, which are highlighted below. According to a InformationWeek 2013 Survey of Analytics, Business Intelligence and Information Management where 541 business technology professionals contributed as respondents, it was discovered that the biggest concern was deemed to be the scarcity of expertise and high costs associated with the same. This concern was voiced by as many as 38% of the participants. A close second came out to be the issue of data warehouse appliance platforms being expensive, with 33% of those present believing it to be a huge roadblock. Another revelation made in this respect was that 31% professionals weren’t even sure how Data Analytics can create business opportunities for them. Another 17% shared that they found data platform technologies such as Hadoop and NoSQL technologies hard to learn. These results clearly pointed out that there are awareness and expertise issues that also need much attention. Unless the demand-supply gap of Business Intelligence professionals well versed in data analysis technologies is met, this divide is going to affect how companies make the most of their BI campaigns. One of the key action points that can be taken to salvage the situation, is to provide training on Data Analytics concepts. Koenig Solutions offer courses on many such technologies including a course on MCSE SQL Server 2012: BI Platform. So it’s time to brush up your skills and get down to work in a data driven world that awaits you ahead. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Mac 10.6 Universal Binary scipy: cephes/specfun "_aswfa_" symbol not found

    - by Markus
    Hi folks, I can't get scipy to function in 32 bit mode when compiled as a i386/x86_64 universal binary, and executed on my 64 bit 10.6.2 MacPro1,1. My python setup With the help of this answer, I built a 32/64 bit intel universal binary of python 2.6.4 with the intention of using the arch command to select between the architectures. (I managed to make some universal binaries of a few libraries I wanted using lipo.) That all works. I then installed scipy according to the instructions on hyperjeff's article, only with more up-to-date numpy (1.4.0) and skipping the bit about moving numpy aside briefly during the installation of scipy. Now, everything except scipy seems to be working as far as I can tell, and I can indeed select between 32 and 64 bit mode using arch -i386 python and arch -x86_64 python. The error Scipy complains in 32 bit mode: $ arch -x86_64 python -c "import scipy.interpolate; print 'success'" success $ arch -i386 python -c "import scipy.interpolate; print 'success'" Traceback (most recent call last): File "<string>", line 1, in <module> File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/interpolate/__init__.py", line 7, in <module> from interpolate import * File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/interpolate/interpolate.py", line 13, in <module> import scipy.special as spec File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/special/__init__.py", line 8, in <module> from basic import * File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/special/basic.py", line 8, in <module> from _cephes import * ImportError: dlopen(/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/special/_cephes.so, 2): Symbol not found: _aswfa_ Referenced from: /Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/special/_cephes.so Expected in: flat namespace in /Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/special/_cephes.so Attempt at tracking down the problem It looks like scipy.interpolate imports something called _cephes, which looks for a symbol called _aswfa_ but can't find it in 32 bit mode. Browsing through scipy's source, I find an ASWFA subroutine in specfun.f. The only scipy product file with a similar name is specfun.so, but both that and _cephes.so appear to be universal binaries: $ cd /Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/special/ $ file _cephes.so specfun.so _cephes.so: Mach-O universal binary with 2 architectures _cephes.so (for architecture i386): Mach-O bundle i386 _cephes.so (for architecture x86_64): Mach-O 64-bit bundle x86_64 specfun.so: Mach-O universal binary with 2 architectures specfun.so (for architecture i386): Mach-O bundle i386 specfun.so (for architecture x86_64): Mach-O 64-bit bundle x86_64 Ho hum. I'm stuck. Things I may try but haven't figured out how yet include compiling specfun.so myself manually, somehow. I would imagine that scipy isn't broken for all 32 bit machines, so I guess something is wrong with the way I've installed it, but I can't figure out what. I don't really expect a full answer given my fairly unique (?) setup, but if anyone has any clues that might point me in the right direction, they'd be greatly appreciated. (edit) More details to address questions: I'm using gfortran (GNU Fortran from GCC 4.2.1 Apple Inc. build 5646). Python 2.6.4 was installed more-or-less like so: cd /tmp curl -O http://www.python.org/ftp/python/2.6.4/Python-2.6.4.tar.bz2 tar xf Python-2.6.4.tar.bz2 cd Python-2.6.4 # Now replace buggy pythonw.c file with one that supports the "arch" command: curl http://bugs.python.org/file14949/pythonw.c | sed s/2.7/2.6/ > Mac/Tools/pythonw.c ./configure --enable-framework=/Library/Frameworks --enable-universalsdk=/ --with-universal-archs=intel make -j4 sudo make frameworkinstall Scipy 0.7.1 was installed pretty much as described as here, but it boils down to a simple sudo python setup.py install. It would indeed appear that the symbol is undefined in the i386 architecture if you look at the _cephes library with nm, as suggested by David Cournapeau: $ nm -arch x86_64 /Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/special/_cephes.so | grep _aswfa_ 00000000000d4950 T _aswfa_ 000000000011e4b0 d _oblate_aswfa_data 000000000011e510 d _oblate_aswfa_nocv_data (snip) $ nm -arch i386 /Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/scipy/special/_cephes.so | grep _aswfa_ U _aswfa_ 0002e96c d _oblate_aswfa_data 0002e99c d _oblate_aswfa_nocv_data (snip) however, I can't yet explain its absence.

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  • Store XML data in Core Data

    - by ct2k7
    Hi, is there any easy way of store XML data into core data? Currently, my app just pulls the values from the XML file directly, however, this isn't efficient for XML files which holds over 100 entries, thus storing the data in Core Data would be the best option. XML file is called/downloaded/parsed ever time the app opens. With the Core Data, the XML data would be downloaded ever 3600 seconds or so, and refresh the current data in the core data, to reduce the loading time when opening the app. Any ideas on how I can do this? Having reviewed the developer documentation, it doesn't look very tasty.

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  • Where can I find free and open data?

    - by kitsune
    Sooner or later, coders will feel the need to have access to "open data" in one of their projects, from knowing a city's zip to a more obscure information such as the axial tilt of Pluto. I know data.un.org which offers access to the UN's extensive array of databases that deal with human development and other socio-economic issues. The other usual suspects are NASA and the USGS for planetary data. There's an article at readwriteweb with more links. infochimps.org seems to stand out. Personally, I need to find historic commodity prices, stock values and other financial data. All these data sets seem to cost money however. Clarification To clarify, I'm interested in all kinds of open data, because sooner or later, I know I will be in a situation where I could need it. I will try to edit this answer and include the suggestions in a structured manners. A link for financial data was hidden in that readwriteweb article, doh! It's called opentick.com. Looks good so far! Update I stumbled over semantic data in another question of mine on here. There is opencyc ('the world's largest and most complete general knowledge base and commonsense reasoning engine'). A project called UMBEL provides a light-weight, distilled version of opencyc. Umbel has semantic data in rdf/owl/skos n3 syntax. The Worldbank also released a very nice API. It offers data from the last 50 years for about 200 countries

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  • Temporary storage for keeping data between program iterations?

    - by mr.b
    I am working on an application that works like this: It fetches data from many sources, resulting in pool of about 500,000-1,500,000 records (depends on time/day) Data is parsed Part of data is processed in a way to compare it to pre-existing data (read from database), calculations are made, and stored in database. Resulting dataset that has to be stored in database is, however, much smaller in size (compared to original data set), and ranges from 5,000-50,000 records. This process almost always updates existing data, perhaps adds few more records. Then, data from step 2 should be kept somehow, somewhere, so that next time data is fetched, there is a data set which can be used to perform calculations, without touching pre-existing data in database. I should point out that this data can be lost, it's not irreplaceable (key information can be read from database if needed), but it would speed up the process next time. Application components can (and will be) run off different computers (in the same network), so storage has to be reachable from multiple hosts. I have considered using memcached, but I'm not quite sure should I do so, because one record is usually no smaller than 200 bytes, and if I have 1,500,000 records, I guess that it would amount to over 300 MB of memcached cache... But that doesn't seem scalable to me - what if data was 5x that amount? If it were to consume 1-2 GB of cache only to keep data in between iterations (which could easily happen)? So, the question is: which temporary storage mechanism would be most suitable for this kind of processing? I haven't considered using mysql temporary tables, as I'm not sure if they can persist between sessions, and be used by other hosts in network... Any other suggestion? Something I should consider?

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  • Why are data structures so important in interviews?

    - by Vamsi Emani
    I am a newbie into the corporate world recently graduated in computers. I am a java/groovy developer. I am a quick learner and I can learn new frameworks, APIs or even programming languages within considerably short amount of time. Albeit that, I must confess that I was not so strong in data structures when I graduated out of college. Through out the campus placements during my graduation, I've witnessed that most of the biggie tech companies like Amazon, Microsoft etc focused mainly on data structures. It appears as if data structures is the only thing that they expect from a graduate. Adding to this, I see that there is this general perspective that a good programmer is necessarily a one with good knowledge about data structures. To be honest, I felt bad about that. I write good code. I follow standard design patterns of coding, I do use data structures but at the superficial level as in java exposed APIs like ArrayLists, LinkedLists etc. But the companies usually focused on the intricate aspects of Data Structures like pointer based memory manipulation and time complexities. Probably because of my java-ish background, Back then, I understood code efficiency and logic only when talked in terms of Object Oriented Programming like Objects, instances, etc but I never drilled down into the level of bits and bytes. I did not want people to look down upon me for this knowledge deficit of mine in Data Structures. So really why all this emphasis on Data Structures? Does, Not having knowledge in Data Structures really effect one's career in programming? Or is the knowledge in this subject really a sufficient basis to differentiate a good and a bad programmer?

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  • Data structure for pattern matching.

    - by alvonellos
    Let's say you have an input file with many entries like these: date, ticker, open, high, low, close, <and some other values> And you want to execute a pattern matching routine on the entries(rows) in that file, using a candlestick pattern, for example. (See, Doji) And that pattern can appear on any uniform time interval (let t = 1s, 5s, 10s, 1d, 7d, 2w, 2y, and so on...). Say a pattern matching routine can take an arbitrary number of rows to perform an analysis and contain an arbitrary number of subpatterns. In other words, some patterns may require 4 entries to operate on. Say also that the routine (may) later have to find and classify extrema (local and global maxima and minima as well as inflection points) for the ticker over a closed interval, for example, you could say that a cubic function (x^3) has the extrema on the interval [-1, 1]. (See link) What would be the most natural choice in terms of a data structure? What about an interface that conforms a Ticker object containing one row of data to a collection of Ticker so that an arbitrary pattern can be applied to the data. What's the first thing that comes to mind? I chose a doubly-linked circular linked list that has the following methods: push_front() push_back() pop_front() pop_back() [] //overloaded, can be used with negative parameters But that data structure seems very clumsy, since so much pushing and popping is going on, I have to make a deep copy of the data structure before running an analysis on it. So, I don't know if I made my question very clear -- but the main points are: What kind of data structures should be considered when analyzing sequential data points to conform to a pattern that does NOT require random access? What kind of data structures should be considered when classifying extrema of a set of data points?

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  • Five Key Strategies in Master Data Management

    - by david.butler(at)oracle.com
    Here is a very interesting Profit Magazine article on MDM: A recent customer survey reveals the deleterious effects of data fragmentation. by Trevor Naidoo, December 2010   Across industries and geographies, IT organizations have grown in complexity, whether due to mergers and acquisitions, or decentralized systems supporting functional or departmental requirements. With systems architected over time to support unique, one-off process needs, they are becoming costly to maintain, and the Internet has only further added to the complexity. Data fragmentation has become a key inhibitor in delivering flexible, user-friendly systems. The Oracle Insight team conducted a survey assessing customers' master data management (MDM) capabilities over the past two years to get a sense of where they are in terms of their capabilities. The responses, by 27 respondents from six different industries, reveal five key areas in which customers need to improve their data management in order to get better financial results. 1. Less than 15 percent of organizations surveyed understand the sources and quality of their master data, and have a roadmap to address missing data domains. Examples of the types of master data domains referred to are customer, supplier, product, financial and site. Many organizations have multiple sources of master data with varying degrees of data quality in each source -- customer data stored in the customer relationship management system is inconsistent with customer data stored in the order management system. Imagine not knowing how many places you stored your customer information, and whether a customer's address was the most up to date in each source. In fact, more than 55 percent of the respondents in the survey manage their data quality on an ad-hoc basis. It is important for organizations to document their inventory of data sources and then profile these data sources to ensure that there is a consistent definition of key data entities throughout the organization. Some questions to ask are: How do we define a customer? What is a product? How do we define a site? The goal is to strive for one common repository for master data that acts as a cross reference for all other sources and ensures consistent, high-quality master data throughout the organization. 2. Only 18 percent of respondents have an enterprise data management strategy to ensure that data is treated as an asset to the organization. Most respondents handle data at the department or functional level and do not have an enterprise view of their master data. The sales department may track all their interactions with customers as they move through the sales cycle, the service department is tracking their interactions with the same customers independently, and the finance department also has a different perspective on the same customer. The salesperson may not be aware that the customer she is trying to sell to is experiencing issues with existing products purchased, or that the customer is behind on previous invoices. The lack of a data strategy makes it difficult for business users to turn data into information via reports. Without the key building blocks in place, it is difficult to create key linkages between customer, product, site, supplier and financial data. These linkages make it possible to understand patterns. A well-defined data management strategy is aligned to the business strategy and helps create the governance needed to ensure that data stewardship is in place and data integrity is intact. 3. Almost 60 percent of respondents have no strategy to integrate data across operational applications. Many respondents have several disparate sources of data with no strategy to keep them in sync with each other. Even though there is no clear strategy to integrate the data (see #2 above), the data needs to be synced and cross-referenced to keep the business processes running. About 55 percent of respondents said they perform this integration on an ad hoc basis, and in many cases, it is done manually with the help of Microsoft Excel spreadsheets. For example, a salesperson needs a report on global sales for a specific product, but the product has different product numbers in different countries. Typically, an analyst will pull all the data into Excel, manually create a cross reference for that product, and then aggregate the sales. The exact same procedure has to be followed if the same report is needed the following month. A well-defined consolidation strategy will ensure that a central cross-reference is maintained with updates in any one application being propagated to all the other systems, so that data is synchronized and up to date. This can be done in real time or in batch mode using integration technology. 4. Approximately 50 percent of respondents spend manual efforts cleansing and normalizing data. Information stored in various systems usually follows different standards and formats, making it difficult to match the data. A customer's address can be stored in different ways using a variety of abbreviations -- for example, "av" or "ave" for avenue. Similarly, a product's attributes can be stored in a number of different ways; for example, a size attribute can be stored in inches and can also be entered as "'' ". These types of variations make it difficult to match up data from different sources. Today, most customers rely on manual, heroic efforts to match, cleanse, and de-duplicate data -- clearly not a scalable, sustainable model. To solve this challenge, organizations need the ability to standardize data for customers, products, sites, suppliers and financial accounts; however, less than 10 percent of respondents have technology in place to automatically resolve duplicates. It is no wonder, therefore, that we get communications about products we don't own, at addresses we don't reside, and using channels (like direct mail) we don't like. An all-too-common example of a potential challenge follows: Customers end up receiving duplicate communications, which not only impacts customer satisfaction, but also incurs additional mailing costs. Cleansing, normalizing, and standardizing data will help address most of these issues. 5. Only 10 percent of respondents have the ability to share data that was mastered in a master data hub. Close to 60 percent of respondents have efforts in place that profile, standardize and cleanse data manually, and the output of these efforts are stored in spreadsheets in various parts of the organization. This valuable information is not easily shared with the rest of the organization and, more importantly, this enriched information cannot be sent back to the source systems so that the data is fixed at the source. A key benefit of a master data management strategy is not only to clean the data, but to also share the data back to the source systems as well as other systems that need the information. Aside from the source systems, another key beneficiary of this data is the business intelligence system. Having clean master data as input to business intelligence systems provides more accurate and enhanced reporting.  Characteristics of Stellar MDM When deciding on the right master data management technology, organizations should look for solutions that have four main characteristics: enterprise-grade MDM performance complete technology that can be rapidly deployed and addresses multiple business issues end-to-end MDM process management with data quality monitoring and assurance pre-built MDM business relevant applications with data stores and workflows These master data management capabilities will aid in moving closer to a best-practice maturity level, delivering tremendous efficiencies and savings as well as revenue growth opportunities as a result of better understanding your customers.  Trevor Naidoo is a senior director in Industry Strategy and Insight at Oracle. 

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