Good afternoon, all.

I *have* a a working function, but I do not like it.

What I *want to* do (nobody asks me): take a string of arbitrary
length, or an array of such random strings and modify them in a way
that, in the result, all strings are split up into chunks of a maximum string-length.

This sounds and reads so simple that my current solutions make me feel
as dumb as a brick. Here is one of my functions which transforms 1
string:

------------
def string_to_array(str, width)
arr = str.split(/\s/)
items = ''
wwidth = 0
arr.each do |w|
wwidth += w.size + 1
if( width < wwidth )
items << "\n"
wwidth = w.size + 1
end
items << w << ' '
end
# split up again or not, as needed
items.split(/\n/)
end
-------------

An exemplary call of this fuction:

---------------
puts string_to_array(ARGV[0], ARGV[1])
---------------

And the output on the command line:

-----------
me@here:/tmp$ ./test.rb "Ein König mit Krone ist besser als ohne" 15
Ein König mit
Krone ist
besser als
ohne
-----------

Yeah... I am so proud. Trying to simplify the working function, above, I
use to mess it all up and after hours arrive at a new solution which
tends to look terribly like the original. If you say that it must be
ugly, I leave it this way.

Thank you for any hints for an alternative implementation.

Michael

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On 19.12.2016 17:19, Michael Uplawski wrote:

What I *want to* do (nobody asks me): take a string of arbitrary
length, or an array of such random strings and modify them in a way
that, in the result, all strings are split up into chunks of a maximum string-length.

max_len = 10
strings = str.scan /.{1,#{max_len}}/

-----------
me@here:/tmp$ ./test.rb "Ein König mit Krone ist besser als ohne" 15
Ein König mit
Krone ist
besser als
ohne
-----------

You never mentioned that you want word splitting.

irb(main):011:0> str = "Ein König mit Krone ist besser als ohne"

"Ein König mit Krone ist besser als ohne"

irb(main):015:0> str.scan %r{\S.{0,#{max_len - 1}}(?!\S)}

["Ein König mit", "Krone ist", "besser als ohne"]

It seems your last two strings should be one.

Cheers

robert

--
remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/

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Good morning.

On Tue, 20 Dec 2016 19:16:52 +0100,
Robert Klemme <[email protected]> wrote:

On 19.12.2016 17:19, Michael Uplawski wrote:
max_len = 10
strings = str.scan /.{1,#{max_len}}/

Thank you. This is clearly the function that I need.

I am not jubilating for the simple reason, that I understand the
documentation on String.scan only with this concrete example and already
know, that I cannot use the function for anything that I have not yet
seen in code.

It solves my current problem, though.

It seems your last two strings should be one.

Right. That is a bug in my code.

Nice holidays all, happy new year, too, within the limits of the
televised joy.

Cheers

robert

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On 21.12.2016 10:55, Michael Uplawski wrote:

Good morning.

On Tue, 20 Dec 2016 19:16:52 +0100,
Robert Klemme <[email protected]> wrote:

On 19.12.2016 17:19, Michael Uplawski wrote:
max_len = 10
strings = str.scan /.{1,#{max_len}}/

Thank you. This is clearly the function that I need.

Good!

I am not jubilating for the simple reason, that I understand the documentation on String.scan only with this concrete example and already know, that I cannot use the function for anything that I have not yet
seen in code.

You should really get familiar with regular expressions. One book I
usually recommend is "Mastering Regular Expressions" (O'Reilly).

There is also a nice programm called "Regex Coach" which allows to watch
a regex engine match. This is really helpful for learning. Runs under
WINE as well.

http://weitz.de/regex-coach/

It solves my current problem, though.

But note the form above does _not_ do word splitting. For that you need
the other one.

Nice holidays all, happy new year, too, within the limits of the
televised joy.

Same to you!

Kind regards

robert

--
remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/

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On Wed, 21 Dec 2016 19:02:29 +0100,
Robert Klemme <[email protected]> wrote:

You should really get familiar with regular expressions. One book I
usually recommend is "Mastering Regular Expressions" (O'Reilly).

You are probably right. The difficulties that I have with String.scan
(and functions documented in a similar way) are certainly induced by my
using Regexps scarcely and only those, that I already master for some
time.

In which way do you consider the O'Reilly book superior to other
publications or, to simplify, the man-pages to egrep, regex (7) or the
RDoc to Regexp, my principal though rarely consulted sources of
information?

There is also a nice programm called "Regex Coach" which allows to watch
a regex engine match. This is really helpful for learning. Runs under
WINE as well.

http://weitz.de/regex-coach/

I will consider this. Paul Lutus put a “Regular Expression Laboratory”
on his web-site (what did he *not* put on his web-site, actually?). It
is simpler with less options than the “Regex-Coach”: http://arachnoid.com/regex_lab/index.html

It solves my current problem, though.

But note the form above does _not_ do word splitting. For that you need
the other one.

Yes. Word-splitting was not in the original “requirement”; I only want
to ensure that a text fits into a laterally limited space... like, let's
say, for a text-mode spreadsheet program, if line-breaks are activated
for a cell. Of all choices.

Cheerio.

Nice holidays all, happy new year, too, within the limits of the
televised joy.

Same to you!

Kind regards

robert

--
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On 22.12.2016 15:34, Michael Uplawski wrote:

On Wed, 21 Dec 2016 19:02:29 +0100,
Robert Klemme <[email protected]> wrote:

You should really get familiar with regular expressions. One book I
usually recommend is "Mastering Regular Expressions" (O'Reilly).

You are probably right. The difficulties that I have with String.scan
(and functions documented in a similar way) are certainly induced by my
using Regexps scarcely and only those, that I already master for some
time.

The knowledge needed about regular expressions and Ruby's dialect of
them is obviously vast compared to the basic mechanics of these methods.
So the documentation has to leave that "bit" out.

In which way do you consider the O'Reilly book superior to other
publications or, to simplify, the man-pages to egrep, regex (7) or the
RDoc to Regexp, my principal though rarely consulted sources of
information?

The book is not a textbook on formal languages (like the classic
dragonbook) but rather a pragmatic's guide to how modern regex engines
work, why they work that way and what the side effects of the fact are
that most are NFA today (famous exception: sed). It explains how to
write expressions to efficiently match and shows techniques to tackle
specific problems.

https://en.wikipedia.org/wiki/Compilers:_Principles,_Techniques,_and_Tools

Manpages of grep also touch regular expressions very briefly only and do
not explain the concept.

I will consider this. Paul Lutus put a “Regular Expression Laboratory”
on his web-site (what did he *not* put on his web-site, actually?). It
is simpler with less options than the “Regex-Coach”: http://arachnoid.com/regex_lab/index.html

But there is a fundamental difference: that tool will only highlight
matches - something that you can do with IRB or grep (with match
coloring) or any other tool / language. But with the Coach you can
watch how the engine (a NFA btw.) actually matches internally. You see
the backtracking that will occur in certain circumstances etc.

Cheerio.

... Mrs. Sophie!

robert

--
remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/

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On 12/19/2016, Michael Uplawski wrote:

arr = str.split(/\s/)

arr = str.split

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