Re: [PATCH v7 18/21] simplebench/results_to_text: improve view of the table

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

13.11.2020 18:59, Max Reitz wrote:
> On 21.10.20 16:58, Vladimir Sementsov-Ogievskiy wrote:
>> Move to generic format for floats and percentage for error.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>   scripts/simplebench/results_to_text.py | 13 ++++++++++++-
>>   1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/scripts/simplebench/results_to_text.py b/scripts/simplebench/results_to_text.py
>> index 58d909ffd9..479f7ac1d4 100644
>> --- a/scripts/simplebench/results_to_text.py
>> +++ b/scripts/simplebench/results_to_text.py
>> @@ -16,11 +16,22 @@
>>   # along with this program.  If not, see <http://www.gnu.org/licenses/>.
>>   #
>> +import math
>> +
>> +
>> +def format_value(x, stdev):
>> +    stdev_pr = stdev / x * 100
>> +    if stdev_pr < 1.5:
>> +        # don't care too much
>> +        return f'{x:.2g}'
>> +    else:
>> +        return f'{x:.2g} ± {math.ceil(stdev_pr)}%'
> 
> OK, so no magnitude-based precision this time (except for the %f -> %g change).  Works for me.
> 
> Other than that, I personally don’t like the relative standard deviation much, because the absolute SD immediately shows the 68 % boundaries (and an idea on the 95 % boundaries with 2σ), whereas the RSD just gives an impression on how spread out the data is.  (Which I find the absolute SD also does, when given together with the average, which is the case here.)

I realized that for myself, the only thing I need from +-deviation is a kind of "reliability" of the result. And it's more obvious for me in percentage. Looking at the table with a lot of numbers, where most of values have deviation less than +-5%, some values with deviation +-30 would catch the eye immediately. And with absolute SD I have to look through the table more carefully.

> 
> To be completely honest, though, I didn’t even know the term “relative SD” existed until a couple of minutes ago, and I didn’t know it was something that was used at all.
> And if I haven’t seen the RSD used in practice, I can’t confidently say that I have good reasons not to like it.
> 
> But, well, I can’t have any confidence in liking it either, and because the change from ASD to RSD is basically the most important change of this patch (which I can’t really agree is an improvement), I can’t really give an R-b.
> 
> Perhaps this is OK:
> 
> Acked-by: Max Reitz <mreitz@redhat.com>
> 

Thanks!

I don't have strict opinion about how this should look. For now these scripts don't have wide usage... We can always add an option to adjust table view, and I will not mind making absolute SD the default view.


-- 
Best regards,
Vladimir