I have several TSV tables (for any characters below ASCII 32 only common characters are contained, such as '\a\b\t\n\v\f\r\e'). I'd like to put them into a single stream. I think that ASCII control characters can be used to separate them. But I am not sure which ASCII control character (other than the ones already used as shown above) is standard for this purpose. Does anybody know what is the standard?
I don't know of standards for what you suggest.
Many protocols use envelopes with a count for what is to follow (TCP) or an index with offsets and lengths (tar, zip) or an arbitrary unique separator that is defined in the header (multipart MIME). There are some that are a simple series like yours but that have formatting that makes item separation obvious (XML element stream [which differs from a document because it has no root element]).
Is the idea that you might not know from the start how many tables and/or rows there are? (That is the use case for XML element streams.)
␀ seems reasonable, perhaps with final extra ␀ to mark the end of the stream (DOS/Windows program environment block).
␊ making an empty line also seems reasonable (like in SMTP).
␚(^Z) is a common file terminator from the days of CP/M and DOS.
How can I do a conditional change in an .ods document? I have two columns. One of them stores a string and the second a value. I want to search the document with a particular string that I have, say "xyz". If this matches any of the strings that are shown in the first column, I would like a value of 1 to be deducted from the cell in the same row, but from the second column. The data in the .ods document are separated by the different adjoining cells (so a tab?)
As an example, consider the following:
xyz 23
xxy 42
xzz 76
If I have the string "xxy", I would like the bash script to update the .ods file such that it looks as so:
xyz 23
xxy 41
xzz 76
Now, the strings that I am searching for are stored in a seperate .txt file. I would like to iterate over all of the strings in the .txt file and repeatedly perform the described operation in the .ods file. There can be cases where the are multiple occurrences of the same string. Any helps with this?
This should be a comment, but its a bit long
am searching for are stored in a text file.
No. A MS Excel files is not a text file. Its not even a file but rather an embedded filesystem where content is encapsuleted in OLE, or more recently as an xml tree. While there are both OLE and XML parsers available on Unix (I assume you want to run this on Linux/Unix/Posix since you've flagged this with bash, awk and sed) that just gets you access to where the data is stored. You still need a detailled understanding of the file format to be able to make changes. While it may be possible to do this in bash, it would be a lot easier in a dedicated programming language. Several do come with libraries for processing Excel files but vary in their support for file formats. Alternatively you could load it up in openoffice using its UNO API.
Currently i'm working on transforming a xml file to delimited seperated file.I was pondering over the idea of representing multiple values of an attribute field..Currently my idea is to represent the values as below:
First Name;Last Name;E-mail id;Description
Fresher;user1;"|email1#abc.com|;|email2#abc.com|";This user joined as fresher.
My question is;Is there is a standard followed for representation of multiple values.?
How is this scenario taken care in common spreadsheet programs available such as Microsoft excel,openoffice calc and lotus notes 123 when imported into .csv file..??
Based on this i want to make changes to my xslt code..
Appreciate any help in this regard..
According to my experiences it is always good to stick to database normalisation standards. There are a lot of information everywhere in the web for further references.
a) When looking in your proposal what I like is to separate each column with semicolon instead of comma. It's easier to import data to any system later especially when you will deal with different (national) standards of number separation symbols
b) However, which I don't like is the 'e-mail' section. There would be a problem in the following areas:
quotation marks are problems- try to avoid them.
don't separate inside e-mail addresses with the same mark as for column separation. Therefore you shouldn't use semicolon there (what I guess- you can have one or few e-mails for each record).
If you can't introduce database normalisation standards I would propose the following small improvements to your idea:
Fresher;user1;email1#abc.com|email2#abc.com;This user joined as fresher
If you provide that kind of data file I think each of vba user would be able to import it to Excel (or any other system) easily and quickly.
I have two files with different data formats in HDFS. How would a job set up look like, if I needed to reduce across both data files?
e.g. imagine the common word count problem, where in one file you have space as the world delimiter and in another file the underscore. In my approach I need different mappers for the various file formats, that than feed into a common reducer.
How to do that?
Or is there a better solution than mine?
Check out the MultipleInputs class that solves this exact problem. It's pretty neat-- you pass in the InputFormat and optionally the Mapper class.
If you are looking for code examples on google, search for "Reduce-side join", which is where this method is typically used.
On the other hand, sometimes I find it easier to just use a hack. For example, if you have one set of files that is space delimited and the other that is underscore delimited, load both with the same mapper and TextInputFormat and tokenize on both possible delimiters. Count the number of tokens from the two results set. In the word count example, pick the one with more tokens.
This also works if both files are the same delimiter but have a different number of standard columns. You can tokenize on comma then see how many tokens there are. If it is say 5 tokens it is from data set A, if it is 7 tokens it is from data set B.
Is there a standard or open format which can be used to describe the formating of a flat file. My company integrates many different customer file formats. With an XML file it's easy to get or create an XSD to describe the XML file format. I'm looking for something similar to describe a flat file format (fixed width, delimited etc). Stylus Studio uses a proprietary .conv format to do this. That .conv format can be used at runtime to transform an arbitrary flat file to an XML file. I was just wondering if there was any more open or standards based method for doing the same thing.
I'm looking for one method of describing a variety of flat file formats whether they are fixed width or delimited, so CSV is not an answer to this question.
XFlat:
http://www.infoloom.com/gcaconfs/WEB/philadelphia99/lyons.HTM#N29
http://www.unidex.com/overview.htm
For complex cases (e.g. log files) you may consider a lexical parser.
About selecting existing flat file formats: There is the Comma-separated values (CSV) format. Or, more generally, DSV. But these are not "fixed-width", since there's a delimiter character (such as a comma) that separates individual cells. Note that though CSV is standardized, not everybody adheres to the standard. Also, CSV may be to simple for your purposes, since it doesn't allow a rich document structure.
In that respect, the standardized and only slightly more complex (but thus more useful) formats JSON and YAML are a better choice. Both are supported out of the box by plenty of languages.
Your best bet is to have a look at all languages listed as non-binary in this overview and then determine which works best for you.
About describing flat file formats: This could be very easy or difficult, depending on the format. Though in most cases easier solutions exist, one way that will work in general is to view the file format as a formal grammar, and write a lexer/parser for it. But I admit, that's quite† heavy machinery.
If you're lucky, a couple of advanced regular expressions may do the trick. Most formats will not lend themselves for that however.‡ If you plan on writing a lexer/parser yourself, I can advise PLY (Python Lex-Yacc). But many other solutions exists, in many different languages, a lot of them more convenient than the old-school Lex & Yacc. For more, see What parser generator do you recommend?
†: Yes, that may be an understatement.
‡: Even properly describing the email address format is not trivial.
COBOL (whether you like it or not) has a standard format for describing fixed-width record formats in files.
Other file formats, however, are somewhat simpler to describe. A CSV file, for example, is just a list of strings. Often the first row of a CSV file is the column names -- that's the description.
There are examples of using JSON to formulate metadata for text files. This can be applied to JSON files, CSV files and fixed-format files.
Look at http://www.projectzero.org/sMash/1.1.x/docs/zero.devguide.doc/zero.resource/declaration.html
This is IBM's sMash (Project Zero) using JSON to encode metadata. You can easily apply this to flat files.
At the end of the day, you will probably have to define your own file standard that caters specifically to your storage needs. What I suggest is using xml, YAML or JSON as your internal container for all of the file types you receive. On top of this, you will have to implement some extra validation logic to maintain meta-data such as the column sizes of the fixed width files (for importing from and exporting to fixed width). Alternatively, you can store or link a set of metadata to each file you convert to the internal format.
There may be a standard out there, but it's too hard to create 'one size fits all' solutions for these problems. There are entity relationship management tools out there (Talend, others) that make creating these mappings easier, but you will still need to spend a lot of time maintaining file format definitions and rules.
As for enforcing column width, xml might be the best solution as you can describe the formats using xml schemas (with the length restriction). For YAML or JSON, you may have to write your own logic for this, although I'm sure someone else has come up with a solution.
See XML vs comma delimited text files for further reference.
I don't know if there is any standard or open format to describe a flat file format. But one industry has done this: the banking industry. Financial institutions are indeed communicating using standardized message over a dedicated network called SWIFT. SWIFT messages were originally positional (before SWIFTML, the XMLified version). I don't know if it's a good suggestion as it's kinda obscure but maybe you could look at the SWIFT Formatting Guide, it may gives you some ideas.
Having that said, check out Flatworm, an humble flat file parser. I've used it to parse positional and/or CSV file and liked its XML descriptor format. It may be a better suggestion than SWIFT :)
CSV
CSV is a delimited data format that has fields/columns separated by the comma character and records/rows separated by newlines. Fields that contain a special character (comma, newline, or double quote), must be enclosed in double quotes. However, if a line contains a single entry which is the empty string, it may be enclosed in double quotes. If a field's value contains a double quote character it is escaped by placing another double quote character next to it. The CSV file format does not require a specific character encoding, byte order, or line terminator format.
The CSV entry on wikipedia allowed me to find a comparison of data serialization formats that is pretty much what you asked for.
The only similar thing I know of is Hachoir, which can currently parse 70 file formats:
http://bitbucket.org/haypo/hachoir/wiki/Home
I'm not sure if it really counts as a declarative language, since it's plugin parser based, but it seems to work, and is extensible, which may meet your needs just fine.
As an aside, there are interesting standardised, extensible flat-file FORMATS, such as IFF (Interchange File Format).