Re: Relatively prime integers in NumPy

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Sujet : Re: Relatively prime integers in NumPy
De : dpopov (at) *nospam* anl.gov (Popov, Dmitry Yu)
Groupes : comp.lang.python
Date : 13. Jul 2024, 05:10:12
Autres entêtes
Message-ID : <mailman.37.1720840220.2981.python-list@python.org>
References : 1 2 3 4 5 6
Thank you very much. List comprehensions make code much more concise indeed. Do list comprehensions also improve the speed of calculations?
________________________________
From: avi.e.gross@gmail.com <avi.e.gross@gmail.com>
Sent: Friday, July 12, 2024 6:57 PM
To: Popov, Dmitry Yu <dpopov@anl.gov>; 'Popov, Dmitry Yu via Python-list' <python-list@python.org>; oscar.j.benjamin@gmail.com <oscar.j.benjamin@gmail.com>
Subject: RE: Relatively prime integers in NumPy

Dmitry, I clearly did not understand what you wanted earlier as you had not made clear that in your example, you already had progressed to some level where you had the data and were now doing a second step. So, I hesitate to say much until
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Dmitry,



I clearly did not understand what you wanted earlier as you had not made clear that in your example, you already had progressed to some level where you had the data and were now doing a second step. So, I hesitate to say much until either nobody else addressed the issue (as clearly some have) or you explain well enough.



I am guessing you have programming experience in other languages and are not as “pythonic” as some. The code you show may not be quite how others might do it. Some may write mch of your code as a single line of python using a list comprehension such as:



hkl_list = [ [h, k, l] for SOMETHING in RANGE  for SOMETHING2  in RANGE2 for SOMETHING3 in RANGE3]



Where h, k. l come from the somethings.



Back to the real world.





From: Popov, Dmitry Yu <dpopov@anl.gov>
Sent: Friday, July 12, 2024 1:13 PM
To: avi.e.gross@gmail.com; 'Popov, Dmitry Yu via Python-list' <python-list@python.org>; oscar.j.benjamin@gmail.com; Popov, Dmitry Yu <dpopov@anl.gov>
Subject: Re: Relatively prime integers in NumPy



Thank you very much, Oscar.



Using the following code looks like a much better solution than my current Python code indeed.

np.gcd.reduce(np.transpose(a))

or

np.gcd.reduce(a,1)



The next question is how I can generate ndarray of h,k,l indices. This can be easily done from a Python list by using the following code.



import numpy as np

hkl_list=[]

for h in range(0, max_h):

      for k in range(0, max_k):

            for l in range(0, max_l):

                  hkl_local=[]

                  hkl_local.append(h)

                  hkl_local.append(k)

                  hkl_local.append(l)

                  hkl_list.append(hkl_local)

hkl=np.array(hkl_list, dtype=np.int64)

This code will generate a two-dimensional ndarray of h,k,l indices but is it possible to make a faster routine with NumPy?



Regards,

Dmitry







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From: Python-list <python-list-bounces+dpopov=anl.gov@python.org<mailto:python-list-bounces+dpopov=anl.gov@python.org>> on behalf of Popov, Dmitry Yu via Python-list <python-list@python.org<mailto:python-list@python.org>>
Sent: Thursday, July 11, 2024 2:25 PM
To: avi.e.gross@gmail.com<mailto:avi.e.gross@gmail.com> <avi.e.gross@gmail.com<mailto:avi.e.gross@gmail.com>>; 'Popov, Dmitry Yu via Python-list' <python-list@python.org<mailto:python-list@python.org>>
Subject: Re: Relatively prime integers in NumPy



Thank you for your interest. My explanation is too concise indeed, sorry. So far, I have used Python code with three enclosed 'for' loops for this purpose which is pretty time consuming. I'm trying to develop a NumPy based code to make this

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Thank you for your interest. My explanation is too concise indeed, sorry. So far, I have used Python code with three enclosed 'for' loops for this purpose which is pretty time consuming. I'm trying to develop a NumPy based code to make this procedure faster. This routine is kind of 'heart' of the algorithm to index of X-ray Laue diffraction patterns. In our group we have to process huge amount of such patterns. They are collected at a synchrotron radiation facility. Faster indexation routine would help a lot.



This is the code I'm currently using. Any prompts how to implement it in NumPy would be highly appreciated.



for h in range(0, max_h):

      for k in range(0, max_k):

            for l in range(0, max_l):

                  chvec=1

                  maxmult=2

                  if h > 1:                     

                        maxmult=h

                  if k > 1:

                        maxmult=k

                  if l > 1:

                        maxmult=l

                  if h > 1:

                        if maxmult > h:

                              maxmult=h

                  if k > 1:

                        if maxmult > k:

                              maxmult=k

                  if l > 1:

                        if maxmult > l:

                              maxmult=l

                  maxmult=maxmult+1

                  for innen in range(2, maxmult):

                        if h in range(0, (max_h+1), innen):

                              if k in range(0, (max_k+1), innen):

                                    if l in range(0, (max_l+1), innen):

                                          chvec=0

                  if chvec==1:

                        # Only relatively prime integers h,k,l pass to this block of the code





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From: avi.e.gross@gmail.com<mailto:avi.e.gross@gmail.com> <avi.e.gross@gmail.com<mailto:avi.e.gross@gmail.com>>

Sent: Thursday, July 11, 2024 1:22 PM

To: Popov, Dmitry Yu <dpopov@anl.gov<mailto:dpopov@anl.gov>>; 'Popov, Dmitry Yu via Python-list' <python-list@python.org<mailto:python-list@python.org>>

Subject: RE: Relatively prime integers in NumPy



Дмитрий, You may think you explained what you wanted but I do not see what result you expect from your examples. Your request is a bit too esoteric to be a great candidate for being built into a module like numpy for general purpose se but

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Дмитрий,



You may think you explained what you wanted but I do not see what result you

expect from your examples.



Your request is a bit too esoteric to be a great candidate for being built

into a module like numpy for general purpose se but I can imagine it could

be available in modules build on top of numpy.



Is there a reason you cannot solve this mostly outside numpy?



It looks like you could use numpy to select the numbers you want to compare,

then call one of many methods you can easily search for to see  how to use

python to make some list or other data structure for divisors of each number

involved and then use standard methods to compare the lists and exact common

divisors. If needed, you could then put the results back into your original

data structure using numpy albeit the number of matches can vary.



Maybe a better explanation is needed as I cannot see what your latter words

about -1 and 1 are about. Perhaps someone else knows.









-----Original Message-----

From: Python-list <python-list-bounces+avi.e.gross=gmail.com@python.org<mailto:python-list-bounces+avi.e.gross=gmail.com@python.org>> On

Behalf Of Popov, Dmitry Yu via Python-list

Sent: Monday, July 8, 2024 3:10 PM

To: Popov, Dmitry Yu via Python-list <python-list@python.org<mailto:python-list@python.org>>

Subject: Relatively prime integers in NumPy



Dear Sirs.



Does NumPy provide a simple mechanism to identify relatively prime integers,

i.e. integers which don't have a common factor other than +1 or -1? For

example, in case of this array:

[[1,5,8],

  [2,4,8],

  [3,3,9]]

I can imagine a function which would return array of common factors along

axis 0: [1,2,3]. Those triples of numbers along axis 1 with the factor of1

or -1 would be relatively prime integers.



Regards,

Dmitry Popov



Argonne, IL

USA



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Date Sujet#  Auteur
13 Jul 24 o Re: Relatively prime integers in NumPy1Popov, Dmitry Yu

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