When I a wanted to try out your interesting example here I discovered
that it needed a bit more to run.
To begin with the dir command is missing
require'dir'
Then a simple example
aa=.dir climb 'C:\j601'
And something to display the results
,.aa
So like this to start with
require'dir'
climb=: 1 : 0
svdir=. 1!:43 ''
1!:44 svdir [ rr=. u y [ 1!:44 y
subds=. ((('d'e.&>4{"1])#0{"1])@:(1!:0@<)) y,'\*.*' NB. Only subdir names
if. 0~:#subds do. rr=. rr;(u climb)&.>(<y,'\'),&.>subds end.
)
aa=.dir climb 'C:\j601'
$aa
5
$ &.> aa
┌─────┬─┬─┬─┬─┐
│25 54│5│6│2│6│
└─────┴─┴─┴─┴─┘
,.aa
The results from the example is still a bit complicated for a beginner
I guess but it sure looks interesting.
2009/7/17 Devon McCormick <[email protected]>:
> Members of the Forum -
>
> I've recently been playing with a useful utility I'm calling "climb" because
> it climbs a directory tree, doing something at each node. This "doing
> something" is user-specifiable, so this naturally lends itself to an
> adverbial construction, to whit:
>
> climb=: 1 : 0
> svdir=. 1!:43 ''
> 1!:44 svdir [ rr=. u y [ 1!:44 y
> subds=. ((('d'e.&>4{"1])#0{"1])@:(1!:0@<)) y,'\*.*' NB. Only subdir names
> if. 0~:#subds do. rr=. rr;(u climb)&.>(<y,'\'),&.>subds end.
> )
>
> The only very complicated line is the one assigning the subdirectory
> variable "subds". I had originally written this
>
> subds=. jd dir y,'\*.*' NB. Only subdir names
>
> but have since substituted the definitions for "jd" (just directories) and
> "dir" since this makes the function self-contained.
>
> I'm interested in comments on a couple of design choices. First of all, is
> the name good? The more normal terminology has one "walk" a directory
> tree. In fact, the Rosetta code page "Walk Directory Tree" (
> http://rosettacode.org/mw/index.php?title=Walk_Directory_Tree) presents an
> application of this code though the problem statement is poorly worded. It
> states that this algorithm will "[w]alk a given directory tree and print
> files matching a given pattern" when it apparently means not "print files"
> but "display file information", based on the submissions.
>
> Of course, the J function here is more general as it allows one to do
> anything while climbing the tree.
>
> Another design choice has us changing directories to run the supplied verb
> but it's not clear this is really necessary.
>
> Yet another choice is to make this recursive in order to simplify the
> logic. However, if we were to handle the sub-directory navigation more
> explicitly, this opens up the possibility of being able to specify either
> "depth-first" or "breadth-first" processing of the tree rather than the
> implicit "depth-first" approach of recursion.
>
> Finally, when I first attempted to use this to list files matching a certain
> pattern, I had an initial problem specifying my verb. My first attempt,
>
> aa=. (dir&'*Bis-B*.csv') climb 'C:\amisc'
>
> failed. When I examined the behavior of my verb - which intentionally
> ignores the default argument inside "climb" of the current directory path -
> I found this:
> (dir&'*Bis-B*.csv') 'C:\amisc'
> |length error: dir
> | (dir&'*Bis-B*.csv')''
>
> Playing around with some variations led me to this
>
> aa=. ((dir@:])&'*Bis-B*.csv') climb 'C:\amisc'
>
> which worked fine but I'm not clear on why my initial attempt to bind the
> right argument of "dir" fails.
>
> In any case, this is a useful utility that offers some room for improvement
> but I've already used it successfully in a couple of different ways.
>
> --
> Devon McCormick, CFA
> ^me^ at acm.
> org is my
> preferred e-mail
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
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