Create sample_from_sphere_or_ball

[nmegiddo]

The function here samples uniformly from either the ball or the sphere with a given norm with possibly different radii

Description

Please include a summary of the change, motivation and which issue is fixed. Any dependencies changes should also be included.

Fixes # (issue)

Type of change

Please check all relevant options.

• [x] Improvement (non-breaking)
• [x] Bug fix (non-breaking)
• [x] New feature (non-breaking)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Testing

Please describe the tests that you ran to verify your changes. Consider listing any relevant details of your test configuration.

• [ ] Test A
• [ ] Test B

Test Configuration:

• OS
• Python version
• ART version or commit number
• TensorFlow / Keras / PyTorch / MXNet version

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [ ] I have commented my code
• [ ] I have made corresponding changes to the documentation
• [ ] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes

[codecov-commenter]

Codecov Report

Merging #1804 (b7f0686) into dev_1.12.0 (9fa6749) will decrease coverage by 0.00%. The diff coverage is 100.00%.

@@              Coverage Diff               @@
##           dev_1.12.0    #1804      +/-   ##
==============================================
- Coverage       85.57%   85.57%   -0.01%     
==============================================
  Files             271      271              
  Lines           23048    23046       -2     
  Branches         4103     4102       -1     
==============================================
- Hits            19723    19721       -2     
  Misses           2316     2316              
  Partials         1009     1009              

Impacted Files	Coverage Δ
art/attacks/evasion/sign_opt.py	86.49% <ø> (ø)
art/estimators/certification/deep_z/pytorch.py	87.50% <ø> (ø)
...certification/derandomized_smoothing/tensorflow.py	85.00% <100.00%> (ø)
art/attacks/evasion/dpatch.py	91.25% <0.00%> (-0.11%)	:arrow_down:

[lgtm-com[bot]]

This pull request introduces 1 alert when merging a5f0ff2f980ca2e7bc26319f66e8e1ffcef9e5c9 into 9bc3b269e3cb7cb906603704f895fcddf8b1ac72 - view on LGTM.com

new alerts:

• 1 for Module is imported more than once

[lgtm-com[bot]]

This pull request introduces 1 alert when merging dbe994fa46e07392d7eba335700ac1c36c729c6e into 9bc3b269e3cb7cb906603704f895fcddf8b1ac72 - view on LGTM.com

new alerts:

• 1 for Module is imported more than once

[lgtm-com[bot]]

This pull request introduces 1 alert when merging b7f0686219a47f1cfb3f709a1e8834d6c106f115 into 9bc3b269e3cb7cb906603704f895fcddf8b1ac72 - view on LGTM.com

new alerts:

• 1 for Module is imported more than once

[beat-buesser]

Hi @nmegiddo Thank you very much for implementing the correct sampling from norm spheres or balls! I pull this PR to a dev branch to move the function to art.utils.