compression

问题 I'm currently working on a project regarding compression of HDF5 datasets and recently began using h5py. I followed the basic tutorials and was able to open,create and compress a file while it was being created. However, I've been unsuccessful when it comes to compressing an existing file (which is the aim of my work). I've tried opening files using 'r+' and then compressing chunked datasets but the file sizes have remained the same. Any suggestions on what commands to use or am I going about

问题 I have a csv file zipped in bz2 format, like unix/linux do we have any single line command to extrac/decompress the file file.csv.bz2 to file.csv in spark-scala? 回答1: You can use built in function in SparkContext(sc), this worked for me sc.textFile("file.csv.bz2").saveAsTextFile("file.csv") 来源： https://stackoverflow.com/questions/52981195/how-to-extract-a-bz2-file-in-spark

问题 I have a situation where I am generating a XML file to be submitted to a webservice, sometimes due to the amount of data it exceeds 30mb or 50mb. I need to compress the file, using c#, .net framework 4.0, rather one of the nodes which has most of the data.. I have no idea how i am going to do it .. is it possible if someone can give me a example of how I can get this done please. the xml file looks like this <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <HeaderTalk xmlns="http://www

问题 I want to compress a string in Dart (in the browser). I tried this: import 'package:archive/archive.dart'; [...] List<int> stringBytes = UTF8.encode(myString); List<int> gzipBytes = new GZipEncoder().encode(stringBytes); String compressedString = UTF8.decode(gzipBytes, allowMalformed: true); Obviously UTF8.decode is not intended for this and it doesn't work (file is unreadable). What is the right way to compress a string in Dart? 回答1: The compressed list of bytes is probably not a valid UTF8

问题 I want to compress a string in Dart (in the browser). I tried this: import 'package:archive/archive.dart'; [...] List<int> stringBytes = UTF8.encode(myString); List<int> gzipBytes = new GZipEncoder().encode(stringBytes); String compressedString = UTF8.decode(gzipBytes, allowMalformed: true); Obviously UTF8.decode is not intended for this and it doesn't work (file is unreadable). What is the right way to compress a string in Dart? 回答1: The compressed list of bytes is probably not a valid UTF8

问题 I am considering what level of zlib compression to use, and I am curious about the different compression rates for the different compression levels that can be specified in zlib commands. The zlib manual has the following constants for specifying the compression level: #define Z_NO_COMPRESSION 0 #define Z_BEST_SPEED 1 #define Z_BEST_COMPRESSION 9 #define Z_DEFAULT_COMPRESSION (-1) Clearly, a lower the number means lower latency for compression and deflation at the cost of a less-compressed

问题 People, How Can I Zip my iOS app's sqlite database? Because I'm trying to sinc it with the cloud but im having some troubles... Which classes I'm supposed to use to zip it ? please help me out! 回答1: You can use ZipArchive, its a objective c wrapper to zip/unzip - http://code.google.com/p/ziparchive/ for zip :- NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString* dPath = [paths objectAtIndex:0]; NSString* txtfile = [dPath

问题 I'm using h5py to save numpy arrays in HDF5 format from python. Recently, I tried to apply compression and the size of the files I get is bigger... I went from things (every file has several datasets) like this self._h5_current_frame.create_dataset( 'estimated position', shape=estimated_pos.shape, dtype=float, data=estimated_pos) to things like this self._h5_current_frame.create_dataset( 'estimated position', shape=estimated_pos.shape, dtype=float, data=estimated_pos, compression="gzip",

问题 I want to compress and then encrypt my data, and for improved speed (by not having to write to byte arrays and back) decided to chain the streams used for compression and encryption together. It works perfectly when I write (compress and encrypt) the data, but when I try to read the data (decompress and decrypt), the Read operation breaks - simply calling Read once reads exactly 0 bytes, because the first Read always returns 0. Looping as in the below code almost works, except that at a

问题 The problem I'm experiencing is the name of the stored file. The stored file isn't named with the original/uncompressed file name. Instead the stored file is named with the archive name (with the appended ".gz" extension). Expected Result: file.txt.gz {archive name} ....file.txt {stored file name} Actual Result: file.txt.gz {archive name} ....file.txt.gz {stored file name} Reading through the gzip documentation (https://docs.python.org/2.7/library/gzip.html) example code: import gzip import