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• Decoding a compressed short string; uncertain on compression used - Updated

  - by James

  Hi, I have a program that is compressing a string in an unknown way. I know a few inputs and the output produced, but I am not sure what is being used to compress the string. Here are my examples. (just 38 x a, no spaces or anything else) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" Out: "026900211AA63000026900"   (just 32 x a) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" Out: "0209001c1aa7a000020900" (31 x a, then 1 b) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab" Out: "0209000177c553c000020900" (31 x b, then 1 a) In: "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbba" Out: "0209001e7754f38000020900" In: "Hey wot u doing 2day u wanna do something" Out: "02990011C7C62E78CE6B8E3ACD83E81B37C5C5A6B9D1E1B06963DB5E71155C1000029900" (same as previous string, but with a space at the end) In: "Hey wot u doing 2day u wanna do something " Out: "02A90012C7718B9E339AE2EB360FA02CDF17177A674786DF4B1EDAF388AAE08000000002A90000" The only definite thing I can see so far is digit 2 and 3 are the amount of characters (hex value), ie first one is 26 = 38 Also the first 6 digits are repeated at the end Any help / advice would be great, thanks!

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• How can Core Data store an NSData?

  - by mystify

  The documentation says, that core data properties can only store NSString, NSNumber and NSDate types. However, a lot of Core Data users claim Core Data could also store an NSData type. But I wasn't able to see that in the documentation, although the Xcode Data Modeler allows to choose a data type called "binary" (which seems to be NSData). Did I miss something? Is there a hidden place in the documentation that indeed lists NSData for binary stuff?

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• Suggestion for a Data Structure!

  - by Jay

  I have the following requirements for a data structure: Direct access to an element with the help of a key (Key will be an integer, range is also same as integer range) Avoid memory allocation in chunks (Allocate contigous memory for the data structure including the data) Should be able to grow the data structure size dynamically Which data structure would you suggest? Any pointers in the direction will also be of help.

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• What are the benefits of the PHP the different PHP compression libraries?

  - by Christopher W. Allen-Poole

  I've been looking into ways to compress PHP libraries, and I've found several libraries which might be useful, but I really don't know much about them. I've specifically been reading about bcompiler and PHAR libraries. Is there any performance benefit in either of these? Are there any "gotchas" I need to watch out for? What are the relative benefits? Do either of them add to/detract from performance? I'm also interested in learning of other libs which might be out there which are not obvious in the documentation? As an aside, does anyone happen to know whether these work more like zip files which just happen to have the code in there, or if they operate more like Python's pre-compiling which actually runs a pseudo-compiler? ======================= EDIT ======================= I've been asked, "What are you trying to accomplish?" Well, I suppose the answer is that this is all hypothetical. It is a combination of these: What if my pet project becomes the most popular web project on earth and I want to distribute it quickly and easily? (hay, a man can dream, right?) It also seems if using PHAR can be done easily, it would be the best way to create a subversion snapshot. Python has this really cool pre-compiling policy, I wonder if PHP has something like that? These libraries seem to do something similar. Will they do that? Hey, these libraries seem pretty neat, but I'd like clarification on the differences as they seem to do the same thing

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• Finding easily parseable chemical element data

  - by nickname

  I am writing an application that needs simple data found (mostly) on the periodic table of elements, such as atomic mass, atomic number, state, etc. However, I would prefer not to manually enter this data. I managed to find the NIST website (http://www.nist.gov/pml/data/edi.cfm) with all of the data I need, but not in a downloadable format. Where can I find this data? Preferably, it would be in an XML/YAML/JSON/other documented format, however, any format would be helpful.

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• C# - Fast and simple multi dimensional data structures?

  - by Jeremy Rudd

  I need to store multi-dimensional data consisting of numbers in a manner thats easy to work with. I'm capturing data in real time, and once processed I would destroy and GC older data. This data structure must be fast so it won't hit my overall app performance. The faster the better. What are my choices in terms of platform supported data structures? I'm using VS 2010. and .NET 4.

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• New article available in "SOA Suite Essentials for WLI Users" series: Dynamic Data Lookup in a Busin

  - by simone.geib

  It is my pleasure to announce the publishing of another article in our "SOA Suite Essentials for WLI Users" series: "Dynamic Data Lookup in a Business Process: Meta Data Cache Control in Oracle WebLogic Integration and Domain Value Maps in SOA Suite". This article explains how dynamic data can be retrieved in a business process using Domain Value Maps in SOA Suite and shows the similarities to the WLI XML MetaData Cache Control. Lots of customers have asked about this comparison and I hope they will find it useful. The article follows "Setting Web Service and JCA Adapter Endpoints Dynamically in Oracle SOA Suite" which describes how web services and JCA adapter endpoints in SOA Suite can be changed at run-time, and so completes the use case where a BPEL process writes to a file (via file adapter) and the output directory and the file name are set dynamically. Please let me know what you think about the series and this specific article.

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• WP7 “Phantom Data” Source Possibly Revealed?

  - by Bil Simser

  Recently there’s been rumours floating around regarding “phantom” Windows Phone 7 data being magically sent and received on the latest WP7 phones. The news has mostly been floating around twitter so I didn’t pay it much attention. The BBC Technology News picked it up so I thought I would look more into it myself seeing that we have WP7 phones and maybe there was some truth to all this (and more importantly what was the cause). Full disclosure. I don’t have a lot of data points around this. This is from looking at a few phone logs, changing the configuration and looking back again after the change. I haven’t done a clean baseline test nor have I done testing with hundreds of phones. I leave the experience up to the reader to decide. So I went spelunking into the phone logs to see what was up. Most providers will show you data usage, at least on a daily basis. I lucked out with the provider and plan in that they provide hourly breakdowns. Here’s a snapshot from my usage throughout one night. Timestamp Data Usage 12:38:30 AM 2098 Kilobytes 1:30:30 AM 2 Kilobytes 2:38:30 AM 7118 Kilobytes 3:38:30 AM 6622 Kilobytes 4:38:30 AM 76 Kilobytes 5:38:30 AM 29 Kilobytes 6:38:30 AM 19 Kilobytes 7:38:30 AM 20 Kilobytes So a few observations from this data: Data seems to be collected on a regular basis. Looking at some other people phone logs, the times vary but it’s always hourly. There’s not a tremendous amount of data here (about 16 megabytes) but it seems like a lot for 7 hours The phone was connected to my home Wifi during this period Nothing was running and the phone was in a locked state Like I said, not a lot of data but it adds up. 16MB for 7 hours = about 50MB in a 24 hour period. That’s just plain old data being collected (somewhere, somehow) and not actual usage (Marketplace, Email, Browsing, etc.). Besides, when connected to a WiFi network you shouldn’t be charged data usage from your phone company (in theory, YMMV). After reviewing the logs I made a theory that the only thing that could possibly be sending data is the Feedback feature. With no other apps running under lock, what else could it be? In Windows 7 under your Settings the last option is Feedback. This sends feedback to Microsoft to “help improve Windows Phone”. On this page you have three options: Send feedback and use my cellular data connection Send feedback and (presumably) use my WiFi connection Don’t send feedback Knowing what I know about Microsoft, they do use the feedback data. For example some of the placement and inclusion of features in Office 2007 was based on that Feedback data that Office sends (assuming you had opted in). However in the Privacy Statement (it’s long but a good read at least once in your life), the Phone manual, and every other source I could look at there is no information about how much data it’s planning to send, just that it’s sending some data and that “some data charges with your carrier may apply”. Looking back at the logs, I have to wonder. 6MB at 3:30 and *then* 7MB the next hour. That’s a lot of information. And it adds up. 50MB in a 24 hour period X 30 days puts most people over a normal 1GB plan. And frankly why am I paying for a data plan only to have 80% of it chewed up by Microsoft, with no real benefit to me. If they included porn in the 50mb daily transfer I’d be okay with this, but I don’t see any new movies on my phone. So I turned it off. Set Feedback to disabled and wait. I waited. And waited. And generally didn’t use the phone if I could. The next day I went back to look at the data usage logs from the time period after turning the feedback mechanism off. Here are the results. Timestamp Data Usage 1:19:48 PM 0 Kilobytes 2:19:48 PM 0 Kilobytes 3:19:48 PM 0 Kilobytes 4:19:48 PM 678 Kilobytes (took a phone call) 5:19:48 PM 82 Kilobytes 6:19:48 PM 88 Kilobytes 7:20:30 PM 86 Kilobytes (guess they changed their reporting time) 8:20:30 PM 86 Kilobytes 9:20:30 PM 66 Kilobytes 10:20:30 PM 67 Kilobytes 11:20:30 PM 49 Kilobytes 12:20:30 AM 32 Kilobytes 1:20:30 AM 38 Kilobytes 2:20:31 AM 18 Kilobytes 3:20:31 AM 27 Kilobytes 4:20:31 AM 86 Kilobytes 5:20:31 AM 53 Kilobytes 6:20:31 AM 22 Kilobytes 7:22:15 AM 30 Kilobytes (another reporting time change) 8:22:15 AM 29 Kilobytes 9:22:15 AM 74 Kilobytes 10:22:15 AM 154 Kilobytes (phone call) 11:22:15 AM 12 Kilobytes 12:13:27 PM 49 Kilobytes 1:13:27 PM 197 Kilobytes (phone call) Quite a *drastic* change from what Feedback was turned on. I mean for a 24 hour period (sans 3 phone calls) I consumed about 1MB. Still quite a bit of transfer going on but at least it amounts to 30MB per month, not 30MB per day! Like I said this observation is neither scientific or conclusive. You decide what to do but frankly until Microsoft makes this data transfer exempt from your data plan (like that will happen) I would just turn Feedback off. YMMV.

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• Arithmetic Coding Questions

  - by Xophmeister

  I have been reading up on arithmetic coding and, while I understand how it works, all the guides and instructions I've read start with something like: Set up your intervals based upon the frequency of symbols in your data; i.e., more likely symbols get proportionally larger intervals. My main query is, once I have encoded my data, presumably I also need to include this statistical model with the encoding, otherwise the compressed data can't be decoded. Is that correct? I don't see this mentioned anywhere -- the most I've seen is that you need to include the number of iterations (i.e., encoded symbols) -- but unless I'm missing something, this also seems necessary to me. If this is true, that will obviously add an overhead to the final output. At what point does this outweigh the benefits of compression (e.g., say if I'm trying to compress just a few thousand bits)? Will the choice of symbol size also make a significant difference (e.g., if I'm looking at 2-bit words, rather than full octets/whatever)?

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• How a .NET Programmer learn Big Data/Hadoop? [on hold]

  - by Smith Pascal Jr.

  I have been ASP.NET developer for sometime now and I have been reading a lot about Big Data- Hadoop and its future as to how it is the next technology in IT and how it would be useful to create million of jobs in US and elsewhere in the world. Now since Hadoop is an open source big data tool which is managed by Apache Server Foundation Group, I'm assuming I have to be well aware of JAVA - Correct me if I'm wrong. Moreover, How a .NET programmer can learn Big Data and its related technologies and can work professionally full time into this technology? What challenges and opportunities does a .NET professional face while changing the technology platform? Please advice. Thanks

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• Ogre3D : seeking advices about game files management

  - by Tibor

  I'm working on a new game, and its related level editor, based on Ogre3D. I was thinking about how i could manage the game files, knowing that Ogre use .mesh files for models, .material for materials/texture information etc... . At first i thought about a common .zip folder decompressed at runtime (the same way Torchlight and Ogre samples do). But this way the game assets become a monolithic archive, loading takes time, and could be difficult to eventually patch them. So, let's say i have a game object named "Cube" i want to load in my program. Going for modularity, what if i create a compressed file (using zlib compression routines) named Cube.extname, containing its sub-files Cube.mesh, Cube.material and so on ? Are there any alternatives or should i stick with compressed objects? PS: Just to clear things, the answer is unrelated to my program code, at the moment i'm using "resources.cfg" pointing to the OgreSDK media directory.

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• Is it a good practice to use smaller data types for variables to save memory?

  - by ThePlan

  When I learned the C++ language for the first time I learned that besides int, float etc, smaller or bigger versions of these data types existed within the language. For example I could call a variable x int x; or short int x; The main difference being that short int takes 2 bytes of memory while int takes 4 bytes, and short int has a lesser value, but we could also call this to make it even smaller: int x; short int x; unsigned short int x; which is even more restrictive. My question here is if it's a good practice to use separate data types according to what values your variable take within the program. Is it a good idea to always declare variables according to these data types?

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• Photo sharing social platform [closed]

  - by user1696497

  I am working on a photo sharing social platform like Flickr, Photobucket. To start off with I have half a million photos as of now. I want to convert all of these into a single format, compression ratio and use it as an original image. I will be storing original image, re-sized image according to layout and a thumbnail. I have started off with ruby, didn't find supporting libraries. I am considering python as it has a good image processing library and instagram is using it. I want some advise about how the image has to be processed while uploading, efficient way of storage whether database or a file system, image compressions, and precautions to be taken. I would be having profile pictures, do I need store them separately or along with the images? If I want to store the images on a file system, which file system should I use and also should I store the url or should I use any intermediate key value store like redis?

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• ?????????????????~BI/DWH????????(2)

  - by Yusuke.Yamamoto

  Oracle Database ???BI???????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????! ??????????(04:19)????????????? Enterprise Manager ?????????????????????????? ???????????????????? Enterprise Manager ??SQL????????????????????I/O?????????? ??????????????Oracle GRID Center ??????????????? ????????????????????????? ????????DWH????????????????·???????? ???? ???????/???????!! ???????????? ~????·???????????????~ ????????: Advanced Compression|??????????? Oracle Enterprise Manager|??????????? DWH(?????????)??·??

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• post image and other data using mulipart form data in iphone

  - by abdulsamad

  Hi all I am sending some data and and an image to the server using multipart/form-data in objective C. kindly give me some Php code that how can i save the image on the server i am able to get the other variables on the server that i am passing with the image. kindly see my obj C code and php and tell me where i am wrong. your help will be highly appreciated. here i make the POST request. ////////////////////// NSString *stringBoundary, *contentType, *baseURLString, *urlString; NSData *imageData; NSURL *url; NSMutableURLRequest *urlRequest; NSMutableData *postBody; // Create POST request from message, imageData, username and password baseURLString = @"http://localhost:8888/Test.php"; urlString = [NSString stringWithFormat:@"%@", baseURLString]; url = [NSURL URLWithString:urlString]; urlRequest = [[[NSMutableURLRequest alloc] initWithURL:url] autorelease]; [urlRequest setHTTPMethod:@"POST"]; // Set the params NSString *path = [[NSBundle mainBundle] pathForResource:@"LibraryIcon" ofType:@"png"]; imageData = [[NSData alloc] initWithContentsOfFile:path]; // Setup POST body stringBoundary = [NSString stringWithString:@"0xKhTmLbOuNdArY"]; contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", stringBoundary]; [urlRequest addValue:contentType forHTTPHeaderField:@"Content-Type"]; // Setting up the POST request's multipart/form-data body postBody = [NSMutableData data]; [postBody appendData:[[NSString stringWithFormat:@"\r\n\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"source\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:@"lighttable"] dataUsingEncoding:NSUTF8StringEncoding]]; // So Light Table show up as source in Twitter post [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"title\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:book.title] dataUsingEncoding:NSUTF8StringEncoding]]; // title [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"isbn\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:book.isbn] dataUsingEncoding:NSUTF8StringEncoding]]; // isbn [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"price\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:txtPrice.text] dataUsingEncoding:NSUTF8StringEncoding]]; // Price [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"condition\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithString:txtCondition.text] dataUsingEncoding:NSUTF8StringEncoding]]; // Price NSString *imageFileName = [NSString stringWithFormat:@"photo.jpeg"]; [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"upload\"; filename=\"%@\"\r\n",imageFileName] dataUsingEncoding:NSUTF8StringEncoding]]; //[postBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"upload\"\r\n\n\n"]dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[@"Content-Type: image/jpeg\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:imageData]; [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]]; // [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]]; NSLog(@"postBody=%@", [[NSString alloc] initWithData:postBody encoding:NSASCIIStringEncoding]); [urlRequest setHTTPBody:postBody]; NSLog(@"Image data=%@",[[NSString alloc] initWithData:imageData encoding:NSASCIIStringEncoding]); // Spawn a new thread so the UI isn't blocked while we're uploading the image [NSThread detachNewThreadSelector:@selector(uploadingDataWithURLRequest:) toTarget:self withObject:urlRequest]; I the method uploadingDataWithURLRequest i post the request to the server... Here is my php Code ?php $title = $_POST['title']; $isbn = $_POST['isbn']; $price = $_POST['price']; $condition = $_POST['condition']; $image=$_FILES['image']['name']; if($image) { $filename = 'newimage.jpeg'; file_put_contents($filename, $image); echo "image is there"; } else { echo "image is nil"; } ?> I am unable to get the image on server kindly help me where i am wrong.

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• Can compressing Program Files save space *and* give a significant boost to SSD performance?

  - by Christopher Galpin

  Considering solid-state disk space is still an expensive resource, compressing large folders has appeal. Thanks to VirtualStore, could Program Files be a case where it might even improve performance? Discovery In particular I have been reading: SSD and NTFS Compression Speed Increase? Does NTFS compression slow SSD/flash performance? Will somebody benchmark whole disk compression (HD,SSD) please? (may have to scroll up) The first link is particularly dreamy, but maybe head a little too far in the clouds. The third link has this sexy semi-log graph (logarithmic scale!). Quote (with notes): Using highly compressable data (IOmeter), you get at most a 30x performance increase [for reads], and at least a 49x performance DECREASE [for writes]. Assuming I interpreted and clarified that sentence correctly, this single user's benchmark has me incredibly interested. Although write performance tanks wretchedly, read performance still soars. It gave me an idea. Idea: VirtualStore It so happens that thanks to sanity saving security features introduced in Windows Vista, write access to certain folders such as Program Files is virtualized for non-administrator processes. Which means, in normal (non-elevated) usage, a program or game's attempt to write data to its install location in Program Files (which is perhaps a poor location) is redirected to %UserProfile%\AppData\Local\VirtualStore, somewhere entirely different. Thus, to my understanding, writes to Program Files should primarily only occur when installing an application. This makes compressing it not only a huge source of space gain, but also a potential candidate for performance gain. Testing The beginning of this post has me a bit timid, it suggests benchmarking NTFS compression on a whole drive is difficult because turning it off "doesn't decompress the objects". However it seems to me the compact command is perfectly capable of doing so for both drives and individual folders. Could it be only marking them for decompression the next time the OS reads from them? I need to find the answer before I begin my own testing.

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• Excel 2010 data validation warning (compatibility mode)

  - by Madmanguruman

  We have some legacy worksheets that were created in Excel 2003, which are used by LabVIEW-based test automation software. The current LabVIEW software can only handle the legacy .xls format, so we're forced to keep these worksheets as-is for the time being. We've migrated to Office 2010 and when working with these worksheets, I see this warning: "The following features in this workbook are not supported by earlier versions of Excel. These features may be lost or degraded when you save this workbook in the currently selected file format. Click Continue to save the workbook anyway. To keep all of your features, click Cancel and then save the file in one of the new file formats." "Significant loss of functionality" "One or more cells in this workbook contain data validation rules which refer to values on other worksheets. These data validation rules will not be saved." When I click 'Find', some cells that do indeed have validation rules are highlighted, but those rules are all on the same worksheet! We're using simple list-based validation, with some cells off to the side containing the valid values (for example, cell B4 has a List with Source "=$D$4:$E$4") This makes no sense to me whatsoever. One, the workbook was created in Excel 2003, so obviously we couldn't implement a feature that doesn't exist. Secondly, the modifications we're making don't involve changing the validation rules at all. Thirdly, the complaint that Excel is making is incorrect! All of the rules are on the same worksheet as the target. As if the story wasn't bizarre enough: I went ahead and saved the worksheet with Excel 2010. I then went to an old computer back in the lab and opened the document with Excel 2003. Guess what - the validations were untouched! My questions are: is this a legitimate bug in Excel 2010, or is this some exotic error in the legacy .xls worksheet that is confusing the heck out of Excel 2010? Has anyone else observed this issue working in compatibility mode?

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• Multidimensional data table?

  - by ShreevatsaR

  [Apologies if this sort of question is off-topic for SuperUser. Please redirect to the right place if so.] There is a 3-dimensional array of values. (That is, instead of a table/2-dimensional array with values in a grid, the values can be thought of in a cube instead.) Is there a way to display this "cube" interactively, ideally on a webpage? Specifically, given the data, it would work something like this: the user selects two of the 3 variables. He then sees a "stack" of tables, one for each value of the third variable (cross-sections, in other words). By selecting the appropriate table from the stack, he can see the (i,j,k) value he wants. The "technology" for displaying such a thing (stacked tables, rotation, etc.) already exists, so this seems the sort of thing that someone ought to have written already. To be clear: I don't need sophisticated graphics necessarily, just the ability to select from cross-sections of variables. But I have no experience with (say, for displaying on a webpage) what web gadgets exist, so I'm clueless how to even search for one. (Google searches like "multidimensional data visualization" didn't throw up anything useful. Google Spreadsheets can do a few kinds of charts which can be embedded on a webpage, but I cannot tell if this is one of them.) [I can imagine how it ought to work for higher dimensions. For four-dimensions, instead of selecting just a stack, you'd first select an (i,j) from an "outer table", which would show all (k,l) values for that (i,j). For higher dimensions, inductively: you select (i,j), and then repeat what you'd do with 2 fewer dimensions.] So has this been written? Is this easy to write? Where ought one to look for such a thing?

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• Tools for displaying a multidimensional data table?

  - by ShreevatsaR

  [Apologies if this sort of question is off-topic for SuperUser. Please redirect to the right place if so.] There is a 3-dimensional array of values. (That is, instead of a table/2-dimensional array with values in a grid, the values can be thought of in a cube instead.) Is there a way to display this "cube" interactively, ideally on a webpage? Specifically, given the data, it would work something like this: the user selects two of the 3 variables. He then sees a "stack" of tables, one for each value of the third variable (cross-sections, in other words). By selecting the appropriate table from the stack, he can see the (i,j,k) value he wants. The "technology" for displaying such a thing (stacked tables, rotation, etc.) already exists, so this seems the sort of thing that someone ought to have written already. To be clear: I don't need sophisticated graphics necessarily, just the ability to select from cross-sections of variables. But I have no experience with (say, for displaying on a webpage) what web gadgets exist, so I'm clueless how to even search for one. (Google searches like "multidimensional data visualization" didn't throw up anything useful. Google Spreadsheets can do a few kinds of charts which can be embedded on a webpage, but I cannot tell if this is one of them.) [I can imagine how it ought to work for higher dimensions. For four-dimensions, instead of selecting just a stack, you'd first select an (i,j) from an "outer table", which would show all (k,l) values for that (i,j). For higher dimensions, inductively: you select (i,j), and then repeat what you'd do with 2 fewer dimensions.] So has this been written? Is this easy to write? Where ought one to look for such a thing?

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• Creating a test database with copied data *and* its own data

  - by Jordan Reiter

  I'd like to create a test database that each day is refreshed with data from the production database. BUT, I'd like to be able to create records in the test database and retain them rather than having them be overwritten. I'm wondering if there is a simple straightforward way to do this. Both databases run on the same server, so apparently that rules out replication? For clarification, here is what I would like to happen: Test database is created with production data I create some test records that I want to keep running on the test server (basically so I can have example records that I can play with) Next day, the database is completely refreshed, but the records I created that day are retained. Records that were untouched that day are replaced with records from the production database. The complication is if a record in the production database is deleted, I want it to be deleted on the test database too, so I do want to get rid of records in the test database that no longer exist in the production database, unless those records were created within the test database. Seems like the only way to do this would be to have some sort of table storing metadata about the records being created? So for example, something like this: CREATE TABLE MetaDataRecords ( id integer not null primary key auto_increment, tablename varchar(100), action char(1), pk varchar(100) ); DELETE FROM testdb.users WHERE NOT EXISTS (SELECT * from proddb.users WHERE proddb.users.id=testdb.users.id) AND NOT EXISTS (SELECT * from testdb.MetaDataRecords WHERE testdb.MetaDataRecords.pk=testdb.users.pk AND testdb.MetaDataRecords.action='C' AND testdb.MetaDataRecords.tablename='users' );

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• Import data in Excel that doesn't have a row delimiter, but number of columns is known

  - by Alex B

  So i have this text file that looks something like this: Header1 Header2 Header3 Header4 A1 B1 C1 D1 A2 B2 C2 D2 and so on. When imported, I'd want the data to format itself in 4 columns. I tried the Get External Data from Text, and it successfully imports it, but it doesn't wrap it around, so it just keeps making columns for every space. I'd want it to go on the next line after 4 (in this case) elements have been added. What's the simplest way to achieve this? EDIT: My answer follows, since I'm not yet allowed to answer my own questions yet. The Excel function I needed is called indirect(). Not sure how it actually works though, so hopefully someone can help out with that, but the function call that worked for me is =INDIRECT(ADDRESS((ROW(A1)-1)*4+COLUMN(A1),1)) which i found over here: http://www.ozgrid.com/forum/showthread.php?t=101584&p=456031#post456031 Note: this required me to add the text to excel where i'd get this row full of columns, and then flip it so that i'd have a column full of rows.

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• saving data from a failing drive

  - by intuited

  An external 3½" HDD seems to be in danger of failing — it's making ticking sounds when idle. I've acquired a replacement drive, and want to know the best strategy to get the data off of the dubious drive with the best chance of saving as much as possible. There are some directories that are more important than others. However, I'm guessing that picking and choosing directories is going to reduce my chances of saving the whole thing. I would also have to mount it, dump a file listing, and then unmount it in order to be able to effectively prioritize directories. Adding in the fact that it's time-consuming to do this, I'm leaning away from this approach. I've considered just using dd, but I'm not sure how it would handle read errors or other problems that might prevent only certain parts of the data from being rescued, or which could be overcome with some retries, but not so many that they endanger other parts of the drive from being saved. I guess ideally it would do a single pass to get as much as possible and then go back to retry anything that was missed due to errors. Is it possible that copying more slowly — e.g. pausing every x MB/GB — would be better than just running the operation full tilt, for example to avoid any overheating issues? For the "where is your backup" crowd: this actually is my backup drive, but it also contains some non-critical and bulky stuff, like music, that aren't backups, i.e. aren't backed up. The drive has not exhibited any clear signs of failure other than this somewhat ominous sound. I did have to fsck a few errors recently — orphaned inodes, incorrect free blocks/inodes counts, inode bitmap differences, zero dtime on deleted inodes; about 20 errors in all. The filesystem of the partition is ext3.

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• Recovering data from an external hard drive

  - by CCallaghan

  I have a WD Elements 2GB hard drive (formatted NTFS). I accidentally kicked out the USB cable while writing data to the disk, and now I can't access most of the data. Although this was ostensibly my backup drive, there is a great deal of important material on there which was only on there. I realise how idiotic this makes me. (So, formatting is not an option.) Things I've tried/information I've gathered: Windows Explorer will recognise the drive itself. However, it will not access most directories therein (and will sometimes crash when exploring). I can access all of the directories through the command line, but the dir command will often report that it can't read any files in most of the directories. The situation was similar when I hooked it up to an Ubuntu machine: the file explorer crashed, but I could access directories - but not files in those directories - via terminal commands. Several files I tried to copy out either resulted in an I/O error being reported or resulted in the command line crashing. The Disk Management utility on Windows reports a healthy disk formatted as NTFS and not RAW. It also indicates the correct amount of space used up and its capacity (so it seems that the files are not deleted). I've tried to run chkdsk, but that hangs on Step 2 (checking indexes) at 74%. Step 1 reported no bad sectors. I tried Recuva, but that didn't seem to work (stalled at 0% for half an hour). I should also note that the disk doesn't seem to be spinning smoothly; it seems to be chopping back, like it's reading the same sector over and over again. I noticed this after I kicked out the cable. Any help would be greatly appreciated. Update: It would seem the problem has taken a turn for the worse. The external hard drive now shows up on my computer as a local disk and is not mountable by Linux.

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• Data recovery on working hard drive

  - by emgee

  So I have a 5 bay hot swap SATA enclosure that's connected to a Silicon Image-based SATA adapter in a computer. It's running XP Pro. There are two 1.5TB hard drives in slots 1 and 2 respectively, set up using RAID 1 using the the Silicon Image utility. There are also two 1TB drives in bays 3 and 4, also set to RAID 1 the same way. The partitions for both RAID arrays are Dynamic partitions. A few days back, there was a bare hard drive that needed some files copied off of, so it was popped it in bay 5, that bay to pass-through, and the copied data off of it. Later, I noticed that my 1.5TB drives no longer showed up in windows. In the Silicon Image utility, the drives showed up fine, no error. However, in Device Manager, it shows the RAID 1 array as uninitialized. It shows up as the right size, etc., but nothing else. There's no sign of anything wrong with either drive, so I'm not sure what happened exactly. I'm not the only one who has access to that computer, so it is possible there is something else done to it that I don't know of. There's quite a lot of data on it still, and if at all possible, I'd prefer to not send it to Ontrack. Does anyone know of software that would restore the partitions, keeping in mind that it's a Windows LDM partition? I have access to a variety of Operating Systems, so something that would work on Mac, Windows or Linux would be acceptable. The programs I usually use are not compatible with LDM.

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• Easily Plotting Multiple Data Series in Excel

  - by John

  I really need help figuring out how to speed up graphing multiple series on a graph. I have seperate devices that give monthly readings for several variables like pressure, temperature, and salinity. Each of these variables is going to be its own graph with devices being the series. My x-axis is going to be the dates that these values were taken. The problem is that it takes ages to do this for each spreadsheet since I have monthly dates from 1950 up to the present and I have about 50 devices in each spreadsheet. I also have graphs for calculated values that are in columns next to them. Each of these devices is going to become a data series in the graph. E.g. In one of my graphs I have all the pressures from the devices and each of the data series' names is the name of the device. I want a fast way to do this. Doing this manually is taking a very long time. Please help! Is there any easier way to do this? It is consistent and the dates all line up. I am just repeating the same clicks over and over again Thank you!

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