Re: [Python-Dev] [Csv] skipfinalspace

[Tom Brown]

On Mon, Oct 20, 2008 at 00:48, John Machin <[EMAIL PROTECTED]> wrote:

> Tom Brown wrote:
>
>> (Continuing thread started at
>> http://mail.python.org/pipermail/csv/2008-October/000688.html)
>>
>> On Sun, Oct 19, 2008 at 16:46, Andrew McNamara <
>> [EMAIL PROTECTED] > wrote:
>>
>> >I downloaded the 2.6 source tar ball, but is it too late for new
>>features to
>> >get into versions <3?
>>
>>Yep.
>>
>> >How would you feel about adding the following tests to
>>Lib/test/test_csv.py
>> >and getting them to pass?
>> >
>> >Also http://www.python.org/doc/2.5.2/lib/csv-fmt-params.html says
>> >"*skipinitialspace *When True, whitespace immediately following the
>> >delimiter is ignored."
>> >but my tests show whitespace at the start of any field is ignored,
>>including
>> >the first field.
>>
>>I suspect (but I haven't checked) that it means "after the delimiter
>> and
>>before any quoted field (or some variation on that).
>>
>> I agree that whitespace after the delimiter and before any quoted field is
>> skipped. Also whitespace after the start of the line and before any quoted
>> field is skipped.
>>
>
> All of the "dialect" parameters are there to allow parsing of a
>> specific
>>common form of CSV file. Because there is no formal definition of the
>>format, the module simply aims to parse (and produce the same result)
>>as common applications such as Excel and Access. Changing the behaviour
>>in any non-backwards compatible way is sure to get screams of anguish
>>from many users. Even when the behaviour appears to be a bug, you can
>>be sure people are counting on it working like that.
>>
>>
>> skipinitialspace defaults to false and by the same logic skipfinalspace
>> should default to false to preserve compatibility with the csv module in
>> 2.6. On the other hand, the switch to version 3 is as good a time as any to
>> break backwards compatibility to adopt something that works better for new
>> users.
>>
>
> Read Andrew's lips: They don't want "better", they want "the same as MS".

okay.


>
>
>  Based on my experience parsing several hundred csv generated by many
>> different people I think it would be nice to at least have a dialect that is
>> excel + skipinitialspace=True + skipfinalspace=True.
>>
>
> Based on my experience extracting data from innumerable csv files (and
> infinite varieties thereof),

Wow, that is a _lot_ of files :-P

spreadsheet files, and database tables, in 99.99% of cases one should
> automatically apply the following transformations to each text field:
>   * strip leading whitespace
>   * strip trailing whitespace
>   * replace embedded runs of whitespace by a single space
> and one needs to ensure that the definition of whitespace includes the
> no-break space (NBSP) character.
>
> As this "space normalisation" is needed for all input sources, the csv
> module is IMHO the wrong place to put it. A string method would be a better
> idea.


I agree that strip() and something like re.sub(r"\s+", " " are handy. If
99.99% percent of csv readers should be applying these fixes to every field
perhaps there should be easy-to-enable option to apply it. Why force almost
everyone to discover they need the transformations and put a line of code
around csv reader?
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Re: [Python-Dev] Python 2.5.3: call for patches

[Jeroen Ruigrok van der Werven]

-On [20081020 19:07], A.M. Kuchling ([EMAIL PROTECTED]) wrote:
>This fixes a memory leak in itertools.chain(), which was greatly
>changed between 2.5 and 2.6, and the patch was to code not present in
>2.5.  Are you sure this bug affected 2.5 at all?

No, my mind was caught up between versions, so Raymond's closing the issue
is the logical thing to do. Apologies for wasting those few minutes.

-- 
Jeroen Ruigrok van der Werven  / asmodai
イェルーン ラウフロック ヴァン デル ウェルヴェン
http://www.in-nomine.org/ | http://www.rangaku.org/ | GPG: 2EAC625B
Nothing is more honorable than enlightenment, nothing is more beautiful
than virtue...
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Re: [Python-Dev] [Csv] skipfinalspace

[Magnus Lie Hetland]

On Oct 20, 2008, at 09:48, John Machin wrote:

Based on my experience extracting data from innumerable csv files  
(and infinite varieties thereof), spreadsheet files, and database  
tables, in 99.99% of cases one should automatically apply the  
following transformations to each text field:

  * strip leading whitespace
  * strip trailing whitespace
  * replace embedded runs of whitespace by a single space
and one needs to ensure that the definition of whitespace includes  
the no-break space (NBSP) character.


As this "space normalisation" is needed for all input sources, the  
csv module is IMHO the wrong place to put it. A string method would  
be a better idea.


Hm. It seems quite familiar, somehow...

You could certainly do the following (for each field)...

  " ".join(field.split())

... but I seem to recall running across something that did this?  
(Maybe I'm confusing it with some other issue, with the  
string.capwords function versis str.title :)


--
Magnus Lie Hetland
http://hetland.org


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