Re: [Numpy-discussion] quantile() or percentile()

[Chris Barker]

+1 on quantile()

-CHB


On Sun, Aug 13, 2017 at 6:28 AM, Charles R Harris  wrote:

>
>
> On Thu, Aug 10, 2017 at 3:08 PM, Eric Wieser 
> wrote:
>
>> Let’s try and keep this on topic - most replies to this message has been
>> about #9211, which is an orthogonal issue.
>>
>> There are two main questions here:
>>
>>1. Would the community prefer to use np.quantile(x, 0.25) instead of 
>> np.percentile(x,
>>25), if they had the choice
>>2. Is this desirable enough to justify increasing the API surface?
>>
>> The general consensus on the github issue answers yes to 1, but is
>> neutral on 2. It would be good to get more opinions.
>>
>
> I think a quantile function would be natural and desirable.
>
> 
>
> Chuck
>
>
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Re: [Numpy-discussion] quantile() or percentile()

[josef . pktd]

On Sun, Aug 13, 2017 at 9:28 AM, Charles R Harris  wrote:

>
>
> On Thu, Aug 10, 2017 at 3:08 PM, Eric Wieser 
> wrote:
>
>> Let’s try and keep this on topic - most replies to this message has been
>> about #9211, which is an orthogonal issue.
>>
>> There are two main questions here:
>>
>>1. Would the community prefer to use np.quantile(x, 0.25) instead of 
>> np.percentile(x,
>>25), if they had the choice
>>2. Is this desirable enough to justify increasing the API surface?
>>
>> The general consensus on the github issue answers yes to 1, but is
>> neutral on 2. It would be good to get more opinions.
>>
>
> I think a quantile function would be natural and desirable.
>

I'm in favor of adding it. (moving away from +0)
It should be an obvious code completion choice, np.q?

Josef



>
> 
>
> Chuck
>
>
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Re: [Numpy-discussion] quantile() or percentile()

[Joseph Fox-Rabinovitz]

I will go over your PR carefully to make sure we can agree on a
matching API. After that, we can swap the backend out whenever I get
around to it.

Thanks for working on this.

-Joe

On Thu, Aug 3, 2017 at 5:36 PM, Chun-Wei Yuan  wrote:
> Cool.  Just as a heads up, for my algorithm to work, I actually need the
> indices, which is why argsort() is so important to me.  I use it to get both
> ap_sorted and ws_sorted variables.  If your weighted-quantile algo is faster
> and doesn't require those indices, please by all means change my
> implementation.  Thanks.
>
> On Thu, Aug 3, 2017 at 11:10 AM, Joseph Fox-Rabinovitz
>  wrote:
>>
>> Not that I know of. The algorithm is very simple, requiring a
>> relatively small addition to the current introselect algorithm used
>> for `np.partition`. My biggest hurdle is figuring out how the calling
>> machinery really works so that I can figure out which input type
>> permutations I need to generate, and how to get the right backend
>> running for a given function call.
>>
>> -Joe
>>
>> On Thu, Aug 3, 2017 at 1:00 PM, Chun-Wei Yuan 
>> wrote:
>> > Any way I can help expedite this?
>> >
>> > On Fri, Jul 21, 2017 at 4:42 PM, Chun-Wei Yuan 
>> > wrote:
>> >>
>> >> That would be great.  I just used np.argsort because it was familiar to
>> >> me.  Didn't know about the C code.
>> >>
>> >> On Fri, Jul 21, 2017 at 3:43 PM, Joseph Fox-Rabinovitz
>> >>  wrote:
>> >>>
>> >>> While #9211 is a good start, it is pretty inefficient in terms of the
>> >>> fact that it performs an O(nlogn) sort of the array. It is possible to
>> >>> reduce the time to O(n) by using a similar partitioning algorithm to
>> >>> the one
>> >>> in the C code of percentile. I will look into it as soon as I can.
>> >>>
>> >>> -Joe
>> >>>
>> >>> On Fri, Jul 21, 2017 at 5:34 PM, Chun-Wei Yuan
>> >>> 
>> >>> wrote:
>> 
>>  Just to provide some context, 9213 actually spawned off of this guy:
>> 
>>  https://github.com/numpy/numpy/pull/9211
>> 
>>  which might address the weighted inputs issue Joe brought up.
>> 
>>  C
>> 
>>  On Fri, Jul 21, 2017 at 2:21 PM, Joseph Fox-Rabinovitz
>>   wrote:
>> >
>> > I think that there would be a very good reason to have a separate
>> > function if we were to introduce weights to the inputs, similarly to
>> > the way
>> > that we have mean and average. This would have some (positive)
>> > repercussions
>> > like making weighted histograms with the Freedman-Diaconis binwidth
>> > estimator a possibility. I have had this change on the back-burner
>> > for a
>> > long time, mainly because I was too lazy to figure out how to
>> > include it in
>> > the C code. However, I will take a closer look.
>> >
>> > Regards,
>> >
>> > -Joe
>> >
>> >
>> >
>> > On Fri, Jul 21, 2017 at 5:11 PM, Chun-Wei Yuan
>> > 
>> > wrote:
>> >>
>> >> There's an ongoing effort to introduce quantile() into numpy.
>> >> You'd
>> >> use it just like percentile(), but would input your q value in
>> >> probability
>> >> space (0.5 for 50%):
>> >>
>> >> https://github.com/numpy/numpy/pull/9213
>> >>
>> >> Since there's a great deal of overlap between these two functions,
>> >> we'd like to solicit opinions on how to move forward on this.
>> >>
>> >> The current thinking is to tolerate the redundancy and keep both,
>> >> using one as the engine for the other.  I'm partial to having
>> >> quantile
>> >> because 1.) I prefer probability space, and 2.) I have a PR waiting
>> >> on
>> >> quantile().
>> >>
>> >> Best,
>> >>
>> >> C
>> >>
>> >> ___
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>> >> https://mail.python.org/mailman/listinfo/numpy-discussion
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Re: [Numpy-discussion] quantile() or percentile()

[Joseph Fox-Rabinovitz]

Not that I know of. The algorithm is very simple, requiring a
relatively small addition to the current introselect algorithm used
for `np.partition`. My biggest hurdle is figuring out how the calling
machinery really works so that I can figure out which input type
permutations I need to generate, and how to get the right backend
running for a given function call.

-Joe

On Thu, Aug 3, 2017 at 1:00 PM, Chun-Wei Yuan  wrote:
> Any way I can help expedite this?
>
> On Fri, Jul 21, 2017 at 4:42 PM, Chun-Wei Yuan 
> wrote:
>>
>> That would be great.  I just used np.argsort because it was familiar to
>> me.  Didn't know about the C code.
>>
>> On Fri, Jul 21, 2017 at 3:43 PM, Joseph Fox-Rabinovitz
>>  wrote:
>>>
>>> While #9211 is a good start, it is pretty inefficient in terms of the
>>> fact that it performs an O(nlogn) sort of the array. It is possible to
>>> reduce the time to O(n) by using a similar partitioning algorithm to the one
>>> in the C code of percentile. I will look into it as soon as I can.
>>>
>>> -Joe
>>>
>>> On Fri, Jul 21, 2017 at 5:34 PM, Chun-Wei Yuan 
>>> wrote:

 Just to provide some context, 9213 actually spawned off of this guy:

 https://github.com/numpy/numpy/pull/9211

 which might address the weighted inputs issue Joe brought up.

 C

 On Fri, Jul 21, 2017 at 2:21 PM, Joseph Fox-Rabinovitz
  wrote:
>
> I think that there would be a very good reason to have a separate
> function if we were to introduce weights to the inputs, similarly to the 
> way
> that we have mean and average. This would have some (positive) 
> repercussions
> like making weighted histograms with the Freedman-Diaconis binwidth
> estimator a possibility. I have had this change on the back-burner for a
> long time, mainly because I was too lazy to figure out how to include it 
> in
> the C code. However, I will take a closer look.
>
> Regards,
>
> -Joe
>
>
>
> On Fri, Jul 21, 2017 at 5:11 PM, Chun-Wei Yuan 
> wrote:
>>
>> There's an ongoing effort to introduce quantile() into numpy.  You'd
>> use it just like percentile(), but would input your q value in 
>> probability
>> space (0.5 for 50%):
>>
>> https://github.com/numpy/numpy/pull/9213
>>
>> Since there's a great deal of overlap between these two functions,
>> we'd like to solicit opinions on how to move forward on this.
>>
>> The current thinking is to tolerate the redundancy and keep both,
>> using one as the engine for the other.  I'm partial to having quantile
>> because 1.) I prefer probability space, and 2.) I have a PR waiting on
>> quantile().
>>
>> Best,
>>
>> C
>>
>> ___
>> NumPy-Discussion mailing list
>> NumPy-Discussion@python.org
>> https://mail.python.org/mailman/listinfo/numpy-discussion
>>
>
>
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Re: [Numpy-discussion] quantile() or percentile()

[Chun-Wei Yuan]

Any way I can help expedite this?

On Fri, Jul 21, 2017 at 4:42 PM, Chun-Wei Yuan 
wrote:

> That would be great.  I just used np.argsort because it was familiar to
> me.  Didn't know about the C code.
>
> On Fri, Jul 21, 2017 at 3:43 PM, Joseph Fox-Rabinovitz <
> jfoxrabinov...@gmail.com> wrote:
>
>> While #9211 is a good start, it is pretty inefficient in terms of the
>> fact that it performs an O(nlogn) sort of the array. It is possible to
>> reduce the time to O(n) by using a similar partitioning algorithm to the
>> one in the C code of percentile. I will look into it as soon as I can.
>>
>> -Joe
>>
>> On Fri, Jul 21, 2017 at 5:34 PM, Chun-Wei Yuan 
>> wrote:
>>
>>> Just to provide some context, 9213 actually spawned off of this guy:
>>>
>>> https://github.com/numpy/numpy/pull/9211
>>>
>>> which might address the weighted inputs issue Joe brought up.
>>>
>>> C
>>>
>>> On Fri, Jul 21, 2017 at 2:21 PM, Joseph Fox-Rabinovitz <
>>> jfoxrabinov...@gmail.com> wrote:
>>>
 I think that there would be a very good reason to have a separate
 function if we were to introduce weights to the inputs, similarly to the
 way that we have mean and average. This would have some (positive)
 repercussions like making weighted histograms with the Freedman-Diaconis
 binwidth estimator a possibility. I have had this change on the back-burner
 for a long time, mainly because I was too lazy to figure out how to include
 it in the C code. However, I will take a closer look.

 Regards,

 -Joe



 On Fri, Jul 21, 2017 at 5:11 PM, Chun-Wei Yuan 
 wrote:

> There's an ongoing effort to introduce quantile() into numpy.  You'd
> use it just like percentile(), but would input your q value in probability
> space (0.5 for 50%):
>
> https://github.com/numpy/numpy/pull/9213
>
> Since there's a great deal of overlap between these two functions,
> we'd like to solicit opinions on how to move forward on this.
>
> The current thinking is to tolerate the redundancy and keep both,
> using one as the engine for the other.  I'm partial to having quantile
> because 1.) I prefer probability space, and 2.) I have a PR waiting on
> quantile().
>
> Best,
>
> C
>
> ___
> NumPy-Discussion mailing list
> NumPy-Discussion@python.org
> https://mail.python.org/mailman/listinfo/numpy-discussion
>
>

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Re: [Numpy-discussion] quantile() or percentile()

[Chun-Wei Yuan]

That would be great.  I just used np.argsort because it was familiar to
me.  Didn't know about the C code.

On Fri, Jul 21, 2017 at 3:43 PM, Joseph Fox-Rabinovitz <
jfoxrabinov...@gmail.com> wrote:

> While #9211 is a good start, it is pretty inefficient in terms of the fact
> that it performs an O(nlogn) sort of the array. It is possible to reduce
> the time to O(n) by using a similar partitioning algorithm to the one in
> the C code of percentile. I will look into it as soon as I can.
>
> -Joe
>
> On Fri, Jul 21, 2017 at 5:34 PM, Chun-Wei Yuan 
> wrote:
>
>> Just to provide some context, 9213 actually spawned off of this guy:
>>
>> https://github.com/numpy/numpy/pull/9211
>>
>> which might address the weighted inputs issue Joe brought up.
>>
>> C
>>
>> On Fri, Jul 21, 2017 at 2:21 PM, Joseph Fox-Rabinovitz <
>> jfoxrabinov...@gmail.com> wrote:
>>
>>> I think that there would be a very good reason to have a separate
>>> function if we were to introduce weights to the inputs, similarly to the
>>> way that we have mean and average. This would have some (positive)
>>> repercussions like making weighted histograms with the Freedman-Diaconis
>>> binwidth estimator a possibility. I have had this change on the back-burner
>>> for a long time, mainly because I was too lazy to figure out how to include
>>> it in the C code. However, I will take a closer look.
>>>
>>> Regards,
>>>
>>> -Joe
>>>
>>>
>>>
>>> On Fri, Jul 21, 2017 at 5:11 PM, Chun-Wei Yuan 
>>> wrote:
>>>
 There's an ongoing effort to introduce quantile() into numpy.  You'd
 use it just like percentile(), but would input your q value in probability
 space (0.5 for 50%):

 https://github.com/numpy/numpy/pull/9213

 Since there's a great deal of overlap between these two functions, we'd
 like to solicit opinions on how to move forward on this.

 The current thinking is to tolerate the redundancy and keep both, using
 one as the engine for the other.  I'm partial to having quantile because
 1.) I prefer probability space, and 2.) I have a PR waiting on quantile().

 Best,

 C

 ___
 NumPy-Discussion mailing list
 NumPy-Discussion@python.org
 https://mail.python.org/mailman/listinfo/numpy-discussion


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Re: [Numpy-discussion] quantile() or percentile()

[Chun-Wei Yuan]

Just to provide some context, 9213 actually spawned off of this guy:

https://github.com/numpy/numpy/pull/9211

which might address the weighted inputs issue Joe brought up.

C

On Fri, Jul 21, 2017 at 2:21 PM, Joseph Fox-Rabinovitz <
jfoxrabinov...@gmail.com> wrote:

> I think that there would be a very good reason to have a separate function
> if we were to introduce weights to the inputs, similarly to the way that we
> have mean and average. This would have some (positive) repercussions like
> making weighted histograms with the Freedman-Diaconis binwidth estimator a
> possibility. I have had this change on the back-burner for a long time,
> mainly because I was too lazy to figure out how to include it in the C
> code. However, I will take a closer look.
>
> Regards,
>
> -Joe
>
>
>
> On Fri, Jul 21, 2017 at 5:11 PM, Chun-Wei Yuan 
> wrote:
>
>> There's an ongoing effort to introduce quantile() into numpy.  You'd use
>> it just like percentile(), but would input your q value in probability
>> space (0.5 for 50%):
>>
>> https://github.com/numpy/numpy/pull/9213
>>
>> Since there's a great deal of overlap between these two functions, we'd
>> like to solicit opinions on how to move forward on this.
>>
>> The current thinking is to tolerate the redundancy and keep both, using
>> one as the engine for the other.  I'm partial to having quantile because
>> 1.) I prefer probability space, and 2.) I have a PR waiting on quantile().
>>
>> Best,
>>
>> C
>>
>> ___
>> NumPy-Discussion mailing list
>> NumPy-Discussion@python.org
>> https://mail.python.org/mailman/listinfo/numpy-discussion
>>
>>
>
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Re: [Numpy-discussion] quantile() or percentile()

[Joseph Fox-Rabinovitz]

I think that there would be a very good reason to have a separate function
if we were to introduce weights to the inputs, similarly to the way that we
have mean and average. This would have some (positive) repercussions like
making weighted histograms with the Freedman-Diaconis binwidth estimator a
possibility. I have had this change on the back-burner for a long time,
mainly because I was too lazy to figure out how to include it in the C
code. However, I will take a closer look.

Regards,

-Joe



On Fri, Jul 21, 2017 at 5:11 PM, Chun-Wei Yuan 
wrote:

> There's an ongoing effort to introduce quantile() into numpy.  You'd use
> it just like percentile(), but would input your q value in probability
> space (0.5 for 50%):
>
> https://github.com/numpy/numpy/pull/9213
>
> Since there's a great deal of overlap between these two functions, we'd
> like to solicit opinions on how to move forward on this.
>
> The current thinking is to tolerate the redundancy and keep both, using
> one as the engine for the other.  I'm partial to having quantile because
> 1.) I prefer probability space, and 2.) I have a PR waiting on quantile().
>
> Best,
>
> C
>
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[Numpy-discussion] quantile() or percentile()

[Chun-Wei Yuan]

There's an ongoing effort to introduce quantile() into numpy.  You'd use it
just like percentile(), but would input your q value in probability space
(0.5 for 50%):

https://github.com/numpy/numpy/pull/9213

Since there's a great deal of overlap between these two functions, we'd
like to solicit opinions on how to move forward on this.

The current thinking is to tolerate the redundancy and keep both, using one
as the engine for the other.  I'm partial to having quantile because 1.) I
prefer probability space, and 2.) I have a PR waiting on quantile().

Best,

C
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