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Re: Check if a given value is out of certain range

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  Re: Check if a given value is out of certain range Rob Gaddi <rgaddi@technologyhighland.invalid> - 2015-09-29 16:48 +0000
    Re: Check if a given value is out of certain range Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-29 21:32 +0100
      Re: Check if a given value is out of certain range sohcahtoa82@gmail.com - 2015-09-30 11:31 -0700
        Re: Check if a given value is out of certain range Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-30 23:31 +0100
          Re: Check if a given value is out of certain range Steven D'Aprano <steve@pearwood.info> - 2015-10-02 04:18 +1000
            Re: Check if a given value is out of certain range John Gordon <gordon@panix.com> - 2015-10-01 18:20 +0000
              Re: Check if a given value is out of certain range Steven D'Aprano <steve@pearwood.info> - 2015-10-02 05:19 +1000
                Re: Check if a given value is out of certain range John Gordon <gordon@panix.com> - 2015-10-01 19:41 +0000
                  Re: Check if a given value is out of certain range Marko Rauhamaa <marko@pacujo.net> - 2015-10-01 22:59 +0300
                    Re: Check if a given value is out of certain range Emile van Sebille <emile@fenx.com> - 2015-10-01 13:15 -0700
                    Re: Check if a given value is out of certain range John Gordon <gordon@panix.com> - 2015-10-01 21:45 +0000
                      Re: Check if a given value is out of certain range Ian Kelly <ian.g.kelly@gmail.com> - 2015-10-01 16:03 -0600
                      Re: Check if a given value is out of certain range Chris Kaynor <ckaynor@zindagigames.com> - 2015-10-01 15:48 -0700
                      Re: Check if a given value is out of certain range Ian Kelly <ian.g.kelly@gmail.com> - 2015-10-01 16:01 -0600
                      Re: Check if a given value is out of certain range Steven D'Aprano <steve@pearwood.info> - 2015-10-03 20:29 +1000
                        Re: Check if a given value is out of certain range Bartc <bc@freeuk.com> - 2015-10-03 11:48 +0100
                        Re: Check if a given value is out of certain range Laura Creighton <lac@openend.se> - 2015-10-03 14:12 +0200
                          Re: Check if a given value is out of certain range Steven D'Aprano <steve@pearwood.info> - 2015-10-03 23:51 +1000
                            Re: Check if a given value is out of certain range wxjmfauth@gmail.com - 2015-10-03 07:19 -0700
                          Re: Check if a given value is out of certain range Steven D'Aprano <steve@pearwood.info> - 2015-10-05 00:47 +1100
                            Re: Check if a given value is out of certain range Rustom Mody <rustompmody@gmail.com> - 2015-10-04 19:28 -0700
                              Re: Check if a given value is out of certain range Rustom Mody <rustompmody@gmail.com> - 2015-10-04 19:32 -0700
                      Re: Check if a given value is out of certain range Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-10-03 11:49 -0400
            Re: Check if a given value is out of certain range Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-10-02 00:34 +0100
        Re: Check if a given value is out of certain range Michiel Overtoom <motoom@xs4all.nl> - 2015-10-05 10:18 +0200
          Re: Check if a given value is out of certain range Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-10-05 13:08 +0300
            Re: Check if a given value is out of certain range Marko Rauhamaa <marko@pacujo.net> - 2015-10-05 14:42 +0300
              Re: Check if a given value is out of certain range Chris Angelico <rosuav@gmail.com> - 2015-10-06 00:10 +1100
                Re: Check if a given value is out of certain range Marko Rauhamaa <marko@pacujo.net> - 2015-10-05 16:25 +0300
        Re: Check if a given value is out of certain range Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-10-05 10:19 +0100
    Re: Check if a given value is out of certain range Random832 <random832@fastmail.com> - 2015-09-29 17:04 -0400
      Re: Check if a given value is out of certain range Luca Menegotto <otlucaDELETE@DELETEyahoo.it> - 2015-09-30 07:57 +0200
    Re: Check if a given value is out of certain range Emile van Sebille <emile@fenx.com> - 2015-09-29 14:07 -0700
    Re: Check if a given value is out of certain range Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-29 15:07 -0600
      Re: Check if a given value is out of certain range Steven D'Aprano <steve@pearwood.info> - 2015-09-30 11:55 +1000
        Re: Check if a given value is out of certain range Random832 <random832@fastmail.com> - 2015-09-29 23:08 -0400
          Re: Check if a given value is out of certain range Steven D'Aprano <steve@pearwood.info> - 2015-09-30 13:14 +1000
            Re: Check if a given value is out of certain range Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-29 23:54 -0600
    Re: Check if a given value is out of certain range Tim Chase <python.list@tim.thechases.com> - 2015-09-29 18:44 -0500
      Re: Check if a given value is out of certain range alister <alister.nospam.ware@ntlworld.com> - 2015-09-30 09:41 +0000
        Re: Check if a given value is out of certain range John Gordon <gordon@panix.com> - 2015-09-30 15:42 +0000
        Re: Check if a given value is out of certain range Grant Edwards <invalid@invalid.invalid> - 2015-09-30 15:56 +0000
          Re: Check if a given value is out of certain range Marko Rauhamaa <marko@pacujo.net> - 2015-09-30 21:06 +0300
            Re: Check if a given value is out of certain range alister <alister.nospam.ware@ntlworld.com> - 2015-09-30 20:19 +0000
              Re: Check if a given value is out of certain range Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-30 14:46 -0600
                Re: Check if a given value is out of certain range alister <alister.nospam.ware@ntlworld.com> - 2015-10-01 08:33 +0000
                  Re: Check if a given value is out of certain range Chris Angelico <rosuav@gmail.com> - 2015-10-01 18:37 +1000
                    Re: Check if a given value is out of certain range alister <alister.nospam.ware@ntlworld.com> - 2015-10-01 08:48 +0000
                  Re: Check if a given value is out of certain range Ian Kelly <ian.g.kelly@gmail.com> - 2015-10-01 08:14 -0600
                Re: Check if a given value is out of certain range Steven D'Aprano <steve@pearwood.info> - 2015-10-02 04:59 +1000
              Re: Check if a given value is out of certain range Laura Creighton <lac@openend.se> - 2015-10-01 09:40 +0200
              Re: Check if a given value is out of certain range Laura Creighton <lac@openend.se> - 2015-10-01 09:58 +0200

Page 3 of 3 — ← Prev page 1 2 [3]

#97247

In <mugaov$79k$1@speranza.aioe.org> alister <alister.nospam.ware@ntlworld.com> writes:

> I would stick with the OP's current solution

> Readability Counts!

I agree.  'if x < 0 or x > 10' is perfectly fine.

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon@panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"

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#97248

On 2015-09-30, alister <alister.nospam.ware@ntlworld.com> wrote:
> On Tue, 29 Sep 2015 18:44:33 -0500, Tim Chase wrote:
>
>> On 2015-09-29 21:32, Mark Lawrence wrote:
>>> On 29/09/2015 17:48, Rob Gaddi wrote:
>>> >> Is there any similar elegant way to check if a value is out of
>>> >> certain range?
>>> >> Example - To check if x is either less than zero or greater than
>>> >> ten? Right now I am using x < 0 or x > 10.
>>> >
>>> > not (0 <= x <= 10)
>>> 
>>> Yuck.
>> 
>> Not sure there's much "yuck" to be had there.  It's succinct, easy to
>> read, and correct.  The only improvement might be if you have things to
>> do in both cases, in which case remove the "not" and set the clauses
>> accordingly:
>> 
>>   if 0 <= x <= 10:
>>     success_within_range(x)
>>   else:
>>     fail_out_of_bounds(x)
>> 
>> -tkc
>
> I would stick with the OP's current solution
>
> Readability Counts!

I'm baffled.

If the condition we are trying to check for is when "x is not within a
range of 0-10 inclusive" then this is as readable as it gets:

  not (0 <= x <= 10)         (I)

That's pretty much a literal, word-for-word translation of the
requirement into code.

Sure, you can can apply De Morgans theorom to transform that into

   (x < 0) or (x > 10)       (II)

That's just as correct, but now the code is one step removed from the
requirement statement.

IMO, (I) is _more_ readable than (II)
   
-- 
Grant Edwards               grant.b.edwards        Yow! Boy, am I glad it's
                                  at               only 1971...
                              gmail.com            

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#97250

Grant Edwards <invalid@invalid.invalid>:

>   not (0 <= x <= 10)         (I)
> [...]
>    (x < 0) or (x > 10)       (II)
> [...]
> IMO, (I) is _more_ readable than (II)

IMO, they're equally readable (except that you should drop the redundant
parentheses from (II)).


Marko

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#97257

On Wed, 30 Sep 2015 21:06:02 +0300, Marko Rauhamaa wrote:

> Grant Edwards <invalid@invalid.invalid>:
> 
>>   not (0 <= x <= 10)         (I)
>> [...]
>>    (x < 0) or (x > 10)       (II)
>> [...]
>> IMO, (I) is _more_ readable than (II)
> 
> IMO, they're equally readable (except that you should drop the redundant
> parentheses from (II)).
> 
> 
> Marko

both are correct
the problem with 1 is the human brain is not particularity good with 
negatives*.
to do not (some function) you first of all have to work out some function 
& then invert it, a computer does this without difficulty the human brain 
gets confused which is why I personally consider ii is  more readable 
(YMMV especially if you are working with Boolean maths regularly) this 
example is relatively simple as things get more complex they become more 
error prone error.



*as an example you brain cannot correctly process the following.

Not (think of your left toe)

you are now thinking about it aren't you?


-- 
The UPS is on strike.

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#97268

On Wed, Sep 30, 2015 at 2:19 PM, alister
<alister.nospam.ware@ntlworld.com> wrote:
> On Wed, 30 Sep 2015 21:06:02 +0300, Marko Rauhamaa wrote:
>
>> Grant Edwards <invalid@invalid.invalid>:
>>
>>>   not (0 <= x <= 10)         (I)
>>> [...]
>>>    (x < 0) or (x > 10)       (II)
>>> [...]
>>> IMO, (I) is _more_ readable than (II)
>>
>> IMO, they're equally readable (except that you should drop the redundant
>> parentheses from (II)).
>>
>>
>> Marko
>
> both are correct
> the problem with 1 is the human brain is not particularity good with
> negatives*.
> to do not (some function) you first of all have to work out some function
> & then invert it, a computer does this without difficulty the human brain
> gets confused which is why I personally consider ii is  more readable
> (YMMV especially if you are working with Boolean maths regularly) this
> example is relatively simple as things get more complex they become more
> error prone error.

To me, the negative of one condition (is x in this range) is more
easily processable than the disjunction of two conditions that
together compose the real, more easily understood condition (is x
outside this range). I find it preferable to avoid nested conditions,
not negated conditions, and (II) has more nesting than (I).

Thought mirrors language. In English, we typically would say "x is not
between 0 and 10", not "x is either less than 0 or greater than 10".

> *as an example you brain cannot correctly process the following.
>
> Not (think of your left toe)
>
> you are now thinking about it aren't you?

No, it made me think about thinking. I barely even registered the
phrase "left toe", much less thought about that.

In any case, that's more an issue of being unable to control what
you're thinking about. If I instruct you, "don't raise your right
hand", do you then automatically raise your right hand?

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#97272

On Wed, 30 Sep 2015 14:46:48 -0600, Ian Kelly wrote:

> On Wed, Sep 30, 2015 at 2:19 PM, alister
> <alister.nospam.ware@ntlworld.com> wrote:
>> On Wed, 30 Sep 2015 21:06:02 +0300, Marko Rauhamaa wrote:
>>
>>> Grant Edwards <invalid@invalid.invalid>:
>>>
>>>>   not (0 <= x <= 10)         (I)
>>>> [...]
>>>>    (x < 0) or (x > 10)       (II)
>>>> [...]
>>>> IMO, (I) is _more_ readable than (II)
>>>
>>> IMO, they're equally readable (except that you should drop the
>>> redundant parentheses from (II)).
>>>
>>>
>>> Marko
>>
>> both are correct the problem with 1 is the human brain is not
>> particularity good with negatives*.
>> to do not (some function) you first of all have to work out some
>> function & then invert it, a computer does this without difficulty the
>> human brain gets confused which is why I personally consider ii is 
>> more readable (YMMV especially if you are working with Boolean maths
>> regularly) this example is relatively simple as things get more complex
>> they become more error prone error.
> 
> To me, the negative of one condition (is x in this range) is more easily
> processable than the disjunction of two conditions that together compose
> the real, more easily understood condition (is x outside this range). I
> find it preferable to avoid nested conditions, not negated conditions,
> and (II) has more nesting than (I).
> 
> Thought mirrors language. In English, we typically would say "x is not
> between 0 and 10", not "x is either less than 0 or greater than 10".
> 
>> *as an example you brain cannot correctly process the following.
>>
>> Not (think of your left toe)
>>
>> you are now thinking about it aren't you?
> 
> No, it made me think about thinking. I barely even registered the phrase
> "left toe", much less thought about that.
clearly it did, & you are now consciously aware of you left toe even if 
you try to deny it.
> 
> In any case, that's more an issue of being unable to control what you're
> thinking about. If I instruct you, "don't raise your right hand", do you
> then automatically raise your right hand?

Why is it that the Phrase "Don't Panic" is strongly discouraged in 
emergency situations?

answer because the brain parses the statement as follows and focuses on 
Panic instead of calm.

Don't : I must not do somthing what must i not do
	Panic:  what is there to panic about?
		Holly shit the buildings onfire, Raise Panic


The recommended phase is Stay calm

Stay: 	ok dont change anything, whats next
	Calm 
	ok I am calm that's alright then


I may not have raised my right hand but I though about it (& decided no 
thanks)

getting closer to topic, i work on PBX systems where the VM is capable of 
combining multiple conditions into one super condition using Boolean 
Operators.
Invariably this does not happen & engineers are encoraged to check each 
condition separately because:

1) They are less likely to make a mistake
2) It is more obvious to subsequent engineers exactly what is happening
3) it is a lot easier to amend if req.

on the other hand if i was designing an electronic circuit using discreet 
electronics I would use all available techniques to manipulate the 
equation to make best use of components available
the may be reducing the total gate  count, it may actually increase the 
component count so that I could use only Nand gates, or it may get 
strangely complex so that I could make use of spare gates on existing ic's

Although I would have no difficulty reading the final equation it may not 
be obvious at 1st glance  .





-- 
Blue paint today.
		[Funny to Jack Slingwine, Guy Harris and Hal Pierson.  
Ed.]

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#97273

On Thu, Oct 1, 2015 at 6:33 PM, alister
<alister.nospam.ware@ntlworld.com> wrote:
> The recommended phase is Stay calm
>
> Stay:   ok dont change anything, whats next
>         Calm
>         ok I am calm that's alright then

Yes, because that always works.

Okay. Alright. I'm calm.
*throws snowball*
See? Now you made him mad!

:)

ChrisA

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#97274

On Thu, 01 Oct 2015 18:37:50 +1000, Chris Angelico wrote:

> On Thu, Oct 1, 2015 at 6:33 PM, alister
> <alister.nospam.ware@ntlworld.com> wrote:
>> The recommended phase is Stay calm
>>
>> Stay:   ok dont change anything, whats next
>>         Calm ok I am calm that's alright then
> 
> Yes, because that always works.
> 
> Okay. Alright. I'm calm.
> *throws snowball*
> See? Now you made him mad!
> 
> :)
> 
> ChrisA

No it doesn't always work, but it does have a higher success rate than 
doing a "Corporal Jones"

Apologies to no UK residents who might not get the "Dads Army" reference.


-- 
One small step for man, one giant stumble for mankind.

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#97283

On Thu, Oct 1, 2015 at 2:33 AM, alister
<alister.nospam.ware@ntlworld.com> wrote:
> Why is it that the Phrase "Don't Panic" is strongly discouraged in
> emergency situations?
>
> answer because the brain parses the statement as follows and focuses on
> Panic instead of calm.
>
> Don't : I must not do somthing what must i not do
>         Panic:  what is there to panic about?
>                 Holly shit the buildings onfire, Raise Panic
>
>
> The recommended phase is Stay calm
>
> Stay:   ok dont change anything, whats next
>         Calm
>         ok I am calm that's alright then
>
>
> I may not have raised my right hand but I though about it (& decided no
> thanks)

Again though this is not due to any failure in processing the "not",
but because the phrase "don't panic" suggests that there may be reason
to panic, which leads to panic (assuming for the sake of argument that
this phenomenon is real and not just anecdotal).

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#97298

On Thu, 1 Oct 2015 06:46 am, Ian Kelly wrote:

> On Wed, Sep 30, 2015 at 2:19 PM, alister
> <alister.nospam.ware@ntlworld.com> wrote:

[...]
>> the problem with 1 is the human brain is not particularity good with
>> negatives*.
>> to do not (some function) you first of all have to work out some function
>> & then invert it, a computer does this without difficulty the human brain
>> gets confused which is why I personally consider ii is  more readable
>> (YMMV especially if you are working with Boolean maths regularly) this
>> example is relatively simple as things get more complex they become more
>> error prone error.

In other words, "more complex things are more error prone". Well, sure. That
doesn't tell us much about simple things though.

You are right that there are certain constructs which, when written in terms
of negatives, are harder for people to parse and understand than if written
in more straight-forward positive forms. But others are simpler when
written in the negative:

"No entry to under 18s" versus "Entry to over 18s only"


Ian:
> To me, the negative of one condition (is x in this range) is more
> easily processable than the disjunction of two conditions that
> together compose the real, more easily understood condition (is x
> outside this range). I find it preferable to avoid nested conditions,
> not negated conditions, and (II) has more nesting than (I).
> 
> Thought mirrors language. In English, we typically would say "x is not
> between 0 and 10", not "x is either less than 0 or greater than 10".

I agree with Ian here.


>> *as an example you brain cannot correctly process the following.
>>
>> Not (think of your left toe)
>>
>> you are now thinking about it aren't you?

Actually I'm not, I'm too busy trying to think of a witty reply :-)


> No, it made me think about thinking. I barely even registered the
> phrase "left toe", much less thought about that.

It's a nice trick, but that's all it is -- it's a trick. The problem isn't
that we can't parse and understand the "not", but that few people have
either the mental discipline or the short attention span to not think about
about something once the thought is planted in the mind.

The classic formulation of this idea is the instruction:

Don't think of an elephant!

Sometimes people will use rhinoceros instead.

The more you try to think about *not* thinking of an elephant, the more the
idea of one comes to your consciousness. It takes great discipline, or a
level of flightiness and empty-headedness that is rare even in the post-MTV
and Twitter generation, to consciously think about something else without
going back to the elephant.

Of course, there is a loop-hole. There is always a loop-hole.[1]

In one of Terry Pratchett's Discworld novels, a young witch mentions the
phrase "Don't think of a rhinoceros", and states that it is impossible to
not think of a rhinoceros. The elderly and curmudgeonly, but extremely
powerful, witch Granny Weatherwax confidently dismisses this, and says that
it doesn't work on her, she's not thinking of a rhinoceros. Such is
Granny's reputation for strength of will, and a self-confidence that you
could bend horseshoes on, that her claim is accepted without question.

It's not until quite late in the book that her secret is revealed. Being an
rural witch who has never really travelled much and doesn't hold with book
learning, she has no idea what a rhinoceros is.


> In any case, that's more an issue of being unable to control what
> you're thinking about. If I instruct you, "don't raise your right
> hand", do you then automatically raise your right hand?

I could be wrong, but I seem to recall reading that this is *exactly* what
happens -- the muscles used to raise the right arm trigger
ever-so-slightly. You don't even notice it, but sensitive electrodes can
detect the change in electrical potential in the muscles.




[1] Except when there isn't.



-- 
Steven

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#97269

In a message of Wed, 30 Sep 2015 14:46:48 -0600, Ian Kelly writes:
>Thought mirrors language. In English, we typically would say "x is not
>between 0 and 10", not "x is either less than 0 or greater than 10".

I wonder if that is regional.

I think you may have stacked things with the 'either' and the 'greater
than'.  'Either' doesn't get used much unless you are heading for
'either x or y but not both'.  And everybody says 'more' even when
'greater than' is arguably more precise.

Around here, I would expect
"x is less than 0 or more than 10"

more often than either of your proposed forms.

But yesterday I hit up the students with the 'what do you find
more readable' question.

There was broad consensus that:

if 0 < x < 10 :
   do_something()
else:
   do_something_else()

was plenty more readable than anything using 'not'

so that the class favourite for readability was:

if 0 < x < 10:
   pass
else:
  complain_out_of_range()

though refactoring the whole lot so that you could have an
out_of_range Exception instead of an if had a large number of
supporters.

Laura

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#97270

In a message of Thu, 01 Oct 2015 09:40:58 +0200, Laura Creighton writes:
>'Either' doesn't get used much unless you are heading for
>'either x or y but not both'.

I don't think I was clear in expressing things this way.  What I meant
was, around here at any rate, 'either' is more often used for
emphasis that you can have x or y (but not both).  If there is no
particular emphasis, the 'either' usually gets dropped.

But it would not surprise me to find out that this is regional.

Laura

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