[Jprogramming] How read text file, sort its lines, write it back out?

[Murray Eisenberg]

On 26 May 2013 15:32:47 -0600, Don Guinn <donguinn at gmail.com> wrote:

That does it; thanks!

But how do you know about the optional 'b' argument of fread? I cannot find documentation about fread at all -- either in J701 or J801 using scriptdoc or in the help pages, included with J or on-line.

Where did you find that documented?

And if it's not in the documentation, is this something one is just supposed to intuit, or know only if he's a member of some secret cult and is told as part of initiation rites?

> sortandprint=:4 : 0
> 
> text=.'b' fread y
> 
> text=./:~text
> 
> text=.text,&.>LF
> 
> (;text) fwrite x
> 
> )
> 
> 
> The 'b' option means box each line.
> 
> 
> y is file to read,
> 
> x is file to write sorted.
> 
> 
> If you are dealing with windows and need CRLF as a line separator, replace
> the LF with <CRLF.
> 
> 
> On Sun, May 26, 2013 at 1:50 PM, Murray Eisenberg <murray at math.umass.edu>wrote:
> 
>> I'm really out of practice with J, and the meager-to-nonexistent
>> documentation is not helping me. I have a very simple task to perform. I
>> have a text file infile.txt on my desktop and here's what I want to do:
>> 
>> (1) read the file as lines (so I don't get all the end-of-line symbols);
>> (2) sort the file's lines (alphabetically)
>> (3) write out the result as a new text file, say outfile.txt, also on my
>> desktop.
>> 
>> I can do this trivially in Mathematica:
>> 
>> t = Import["~/Desktop/infile.txt", "Lines"]
>> Export["~/Desktop/outfile.txt", Sort[t]]
>> 
>> But how would I do this in J (which, for longer files, ought to be faster)
>> and how would I discover how to do it? I prefer to use named library
>> functions where applicable.

---
Murray Eisenberg                                    murray at math.umass.edu
Mathematics & Statistics Dept.       
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