GNU bug report logs - #13394
Misalignment for "seq -w"

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Marcel Böhme" <hawkie <at> web.de>
To: bug-coreutils <at> gnu.org
Subject: Misalignment for "seq -w"
Date: Wed, 9 Jan 2013 11:14:53 +0100 (CET)

Dear all,

There are the following problems with the -w parameter of the seq tool:

$seq -w -1 1.0 0
-1.0
0.0
1.0

But it should print:
-1.0
00.0
01.0

A similar problem is observable for: 
$seq -w 10 -.1 1 | head

Best regards,
 Marcel

Message #8 received at 13394 <at> debbugs.gnu.org (full text, mbox):

From: Bernhard Voelker <mail <at> bernhard-voelker.de>
To: Marcel Böhme <hawkie <at> web.de>, Pádraig Brady <P <at> draigbrady.com>
Cc: 13394 <at> debbugs.gnu.org
Subject: Re: bug#13394: Misalignment for "seq -w"
Date: Wed, 09 Jan 2013 11:34:53 +0100

On 01/09/2013 11:14 AM, Marcel Böhme wrote:
> Dear all,
> 
> There are the following problems with the -w parameter of the seq tool:
> 
> $seq -w -1 1.0 0
> -1.0
> 0.0
> 1.0
> 
> But it should print:
> -1.0
> 00.0
> 01.0

Hmm, according to the TEXI manual, the FIRST number should also use
a fixed point decimal representation when the -w option is used:

`-w'
`--equal-width'
     Print all numbers with the same width, by padding with leading
     zeros.  FIRST, STEP, and LAST should all use a fixed point decimal
     representation.  (To have other kinds of padding, use `--format').

Thus, seq is just doing what the manual says:

  $ seq -w -1.0 1.0 0.0
  -1.0
  00.0

But that leaves the question open if there's a reason for this.
I.e. if it's just documented behavior, a requirement of some
standard or due to compatibility reasons.

But as Padraig worked in this area recently ([1]), I think there
is further room for improvement ... and then the documentation
should be fixed.

@Padraig: WDYT?

Have a nice day,
Berny

[1] http://git.sv.gnu.org/cgit/coreutils.git/commit/?id=64d4a280

Message #11 received at 13394 <at> debbugs.gnu.org (full text, mbox):

From: Erik Auerswald <auerswal <at> unix-ag.uni-kl.de>
To: Bernhard Voelker <mail <at> bernhard-voelker.de>
Cc: 13394 <at> debbugs.gnu.org,
	Pádraig Brady <P <at> draigbrady.com>,
	Marcel Böhme <hawkie <at> web.de>
Subject: Re: bug#13394: Misalignment for "seq -w"
Date: Wed, 09 Jan 2013 12:01:51 +0100

Hi,

On 01/09/2013 11:34 AM, Bernhard Voelker wrote:
> On 01/09/2013 11:14 AM, Marcel Böhme wrote:
>>
>> There are the following problems with the -w parameter of the seq tool:
>> [...]
>
> Hmm, according to the TEXI manual, the FIRST number should also use
> a fixed point decimal representation when the -w option is used:
> [...]
> But that leaves the question open if there's a reason for this.
> I.e. if it's just documented behavior, a requirement of some
> standard or due to compatibility reasons.

That seems to be just documented behavior, since seq is not standardized 
by POSIX and other seq implementations ([1],[2],[3]) don't document 
this. On the contrary, a common example is 'seq -w 0 .05 .1'.

This example works fine with GNU seq:

$ seq -w 0 .05 .1
0.00
0.05
0.10

Even when counting to negative numbers:

$ seq -w 0 -.05 -.1
00.00
-0.05
-0.10

Starting with a negative number with a fractional step size breaks equal 
width for non-negative numbers:

$ seq -w -1 .5 1
-1.0
-0.5
0.0
0.5
1.0

$ seq --version | head -n1
seq (GNU coreutils) 8.13

HTH,
Erik

[1] http://man.cat-v.org/unix_8th/1/seq
[2] http://man.cat-v.org/plan_9/1/seq
[3] http://www.freebsd.org/cgi/man.cgi?query=seq&manpath=FreeBSD+9.0-RELEASE

Message #16 received at 13394-done <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Erik Auerswald <auerswal <at> unix-ag.uni-kl.de>
Cc: Bernhard Voelker <mail <at> bernhard-voelker.de>, 13394-done <at> debbugs.gnu.org,
	Marcel Böhme <hawkie <at> web.de>
Subject: Re: bug#13394: Misalignment for "seq -w"
Date: Wed, 09 Jan 2013 12:05:33 +0000

On 01/09/2013 11:01 AM, Erik Auerswald wrote:
> Hi,
>
> On 01/09/2013 11:34 AM, Bernhard Voelker wrote:
>> On 01/09/2013 11:14 AM, Marcel Böhme wrote:
>>>
>>> There are the following problems with the -w parameter of the seq tool:
>>> [...]
>>
>> Hmm, according to the TEXI manual, the FIRST number should also use
>> a fixed point decimal representation when the -w option is used:
>> [...]
>> But that leaves the question open if there's a reason for this.
>> I.e. if it's just documented behavior, a requirement of some
>> standard or due to compatibility reasons.
>
> That seems to be just documented behavior, since seq is not standardized by POSIX and other seq implementations ([1],[2],[3]) don't document this. On the contrary, a common example is 'seq -w 0 .05 .1'.
>
> This example works fine with GNU seq:
>
> $ seq -w 0 .05 .1
> 0.00
> 0.05
> 0.10
>
> Even when counting to negative numbers:
>
> $ seq -w 0 -.05 -.1
> 00.00
> -0.05
> -0.10
>
> Starting with a negative number with a fractional step size breaks equal width for non-negative numbers:
>
> $ seq -w -1 .5 1
> -1.0
> -0.5
> 0.0
> 0.5
> 1.0
>
> $ seq --version | head -n1
> seq (GNU coreutils) 8.13

Looks like a bug. I'll fix with:

diff --git a/src/seq.c b/src/seq.c
index e1b467c..3eb53f8 100644
--- a/src/seq.c
+++ b/src/seq.c
@@ -332,6 +332,8 @@ get_default_format (operand first, operand step, operand last)
             last_width--;  /* don't include space for '.' */
           if (last.precision == 0 && prec)
             last_width++;  /* include space for '.' */
+          if (first.precision == 0 && prec)
+            first_width++;  /* include space for '.' */
           size_t width = MAX (first_width, last_width);
           if (width <= INT_MAX)
             {

Message #19 received at 13394 <at> debbugs.gnu.org (full text, mbox):

From: Erik Auerswald <auerswal <at> unix-ag.uni-kl.de>
To: 13394 <at> debbugs.gnu.org, P <at> draigBrady.com, hawkie <at> web.de
Subject: Re: bug#13394: Misalignment for "seq -w"
Date: Wed, 09 Jan 2013 13:14:37 +0100

On 01/09/2013 01:05 PM, Pádraig Brady wrote:
> On 01/09/2013 11:01 AM, Erik Auerswald wrote:
>> Hi,
>>
>> On 01/09/2013 11:34 AM, Bernhard Voelker wrote:
>>> On 01/09/2013 11:14 AM, Marcel Böhme wrote:
>>>>
>>>> There are the following problems with the -w parameter of the seq tool:
>>>> [...]
>>>
>>> Hmm, according to the TEXI manual, the FIRST number should also use
>>> a fixed point decimal representation when the -w option is used:
>>> [...]
>>> But that leaves the question open if there's a reason for this.
>>> I.e. if it's just documented behavior, a requirement of some
>>> standard or due to compatibility reasons.
>>
>> That seems to be just documented behavior, since seq is not
>> standardized by POSIX and other seq implementations ([1],[2],[3])
>> don't document this. On the contrary, a common example is 'seq -w 0
>> .05 .1'.
>>
>> This example works fine with GNU seq:
>>
>> $ seq -w 0 .05 .1
>> 0.00
>> 0.05
>> 0.10
>>
>> Even when counting to negative numbers:
>>
>> $ seq -w 0 -.05 -.1
>> 00.00
>> -0.05
>> -0.10
>>
>> Starting with a negative number with a fractional step size breaks
>> equal width for non-negative numbers:
>>
>> $ seq -w -1 .5 1
>> -1.0
>> -0.5
>> 0.0
>> 0.5
>> 1.0
>>
>> $ seq --version | head -n1
>> seq (GNU coreutils) 8.13
>
> Looks like a bug. I'll fix with:
>
> diff --git a/src/seq.c b/src/seq.c
> index e1b467c..3eb53f8 100644
> --- a/src/seq.c
> +++ b/src/seq.c
> @@ -332,6 +332,8 @@ get_default_format (operand first, operand step,
> operand last)
> last_width--; /* don't include space for '.' */
> if (last.precision == 0 && prec)
> last_width++; /* include space for '.' */
> + if (first.precision == 0 && prec)
> + first_width++; /* include space for '.' */
> size_t width = MAX (first_width, last_width);
> if (width <= INT_MAX)
> {

The patch looks plausible. ;-)

Thanks,
Erik

Message #22 received at 13394 <at> debbugs.gnu.org (full text, mbox):

From: Bernhard Voelker <mail <at> bernhard-voelker.de>
To: 13394 <at> debbugs.gnu.org, P <at> draigBrady.com, hawkie <at> web.de
Subject: Re: bug#13394: Misalignment for "seq -w"
Date: Wed, 09 Jan 2013 13:42:26 +0100

On 01/09/2013 01:05 PM, Pádraig Brady wrote:
> Looks like a bug. I'll fix with:
> 
> diff --git a/src/seq.c b/src/seq.c
> index e1b467c..3eb53f8 100644
> --- a/src/seq.c
> +++ b/src/seq.c
> @@ -332,6 +332,8 @@ get_default_format (operand first, operand step, operand last)
>               last_width--;  /* don't include space for '.' */
>             if (last.precision == 0 && prec)
>               last_width++;  /* include space for '.' */
> +          if (first.precision == 0 && prec)
> +            first_width++;  /* include space for '.' */
>             size_t width = MAX (first_width, last_width);
>             if (width <= INT_MAX)
>               {

+1

Have a nice day,
Berny

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