use pyflakes to identify simple bugs in sympy and fix them

[certik]

Example:

sudo apt-get install pyflakes

$ pyflakes sympy/integrals/
sympy/integrals/rationaltools.py:3: 'div' imported but unused
sympy/integrals/rationaltools.py:121: redefinition of unused 'symbols' from
line 3
sympy/integrals/risch.py:4: 'Pow' imported but unused
sympy/integrals/risch.py:5: 'Function' imported but unused
sympy/integrals/risch.py:7: 'Atom' imported but unused
sympy/integrals/risch.py:8: 'Integer' imported but unused
sympy/integrals/deltafunctions.py:2: 'Symbol' imported but unused
sympy/integrals/deltafunctions.py:2: 'S' imported but unused
sympy/integrals/deltafunctions.py:2: 'Wild' imported but unused
sympy/integrals/integrals.py:2: 'Pow' imported but unused
sympy/integrals/integrals.py:9: 'apart' imported but unused
sympy/integrals/integrals.py:10: 'limit' imported but unused
sympy/integrals/integrals.py:13: 'DiracDelta' imported but unused
sympy/integrals/integrals.py:13: 'Heaviside' imported but unused
sympy/integrals/integrals.py:111: redefinition of unused 'limit' from line 10
sympy/integrals/__init__.py:8: 'integrate' imported but unused
sympy/integrals/__init__.py:8: 'line_integrate' imported but unused
sympy/integrals/__init__.py:8: 'Integral' imported but unused
sympy/integrals/tests/test_rationaltools.py:4: 'log_to_atan' imported but
unused
sympy/integrals/tests/test_rationaltools.py:4: 'log_to_real' imported but
unused
sympy/integrals/tests/test_rationaltools.py:4: 'ratint_ratpart' imported
but unused
sympy/integrals/tests/test_lineintegrals.py:1: 'cos' imported but unused
sympy/integrals/tests/test_lineintegrals.py:1: 'Integral' imported but unused
sympy/integrals/tests/test_lineintegrals.py:1: 'sympify' imported but unused
sympy/integrals/tests/test_lineintegrals.py:1: 'integrate' imported but unused
sympy/integrals/tests/test_lineintegrals.py:1: 'diff' imported but unused
sympy/integrals/tests/test_lineintegrals.py:1: 'pi' imported but unused
sympy/integrals/tests/test_lineintegrals.py:1: 'sin' imported but unused
sympy/integrals/tests/test_integrals.py:1: redefinition of unused 'atan'
from line 1
sympy/integrals/tests/test_integrals.py:1: 'I' imported but unused
sympy/integrals/tests/test_integrals.py:5: 'skip' imported but unused
sympy/integrals/tests/test_integrals.py:5: 'XFAIL' imported but unused


it finds (among other things) that the Heaviside is imported but never
used, so it should be removed.

Original issue for #4555: http://code.google.com/p/sympy/issues/detail?id=1456
Original author: https://code.google.com/u/104039945248245758823/

[rlamy]

See http://groups.google.com/group/sympy/browse_thread/thread/d073a9ad2d19845 Priit wrote a tool to get a useful pyflakes report. It's at
git://github.com/plaes/sympy.git branch 'pyflakes'. 
I've pulled from it and added a commit removing some unused imports in
sympy/functions/ in my github repo (git://github.com/rlamy/sympy.git, 'pyflakes').

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c1
Original author: https://code.google.com/u/101272611947379421629/

[asmeurer]

There is also pychecker, which shows a lot of things similar to this (I can't get pyflakes to work, so I can't say if it 
does more or not).  You can just install and run pychecker sympy --limit 1000 to see them all (it takes a few 
minutes to run).  I've attached a file of my output.

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c2
Original author: https://code.google.com/u/asmeurer@gmail.com/

[c00w]

I was going to make a patch but I got really lazy. here is my pyflakes output with some of the correct but misidentified things removed.

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c3
Original author: https://code.google.com/u/103714092292933486699/

[Krastanov]

PyLint seems like a better choice according to http://stackoverflow.com/questions/1428872/pylint-pychecker-or-apyflakes

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c4
Original author: https://code.google.com/u/100157245271348669141/

[asmeurer]

If I remember correctly, pylint can be customized, right?  Because I remember that it complained about a bunch of stuff that (in my opinion anyway) was not too important (like lines only slightly longer than 80 chars) , or should actually remain the same (like no spaces around *).

By the way, except for the fact that it's much slower, the fact that pychecker runs the code isn't that big of a deal for sympy.  There will be a handful of things that tools like pylint will incorrectly warn about (because they seem to be wrong in a static sense), but (assumedly) pychecker won't.

Maybe we should just edit the ./setup.py audit command so it can use any of the three.

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c5
Original author: https://code.google.com/u/asmeurer@gmail.com/

[asmeurer]

**Labels:** CodeInCategory-QA CodeInDifficulty-Medium  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c6
Original author: https://code.google.com/u/asmeurer@gmail.com/

[asmeurer]

**Labels:** CodeInImportedIntoSpreadsheet  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c7
Original author: https://code.google.com/u/asmeurer@gmail.com/

[asmeurer]

A note: if you find an actual bug with this (rather than just some code quality problem), a test should be added for it.

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c8
Original author: https://code.google.com/u/asmeurer@gmail.com/

[asmeurer]

**Labels:** CodeInMultiple  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c9
Original author: https://code.google.com/u/asmeurer@gmail.com/

[rlamy]

Note that there are lots of warnings coming from polys/densepolys.py, polys/densetools.py and polys/sparsepolys.py, but these modules are known not to work, cf. issue 5470 .

**Blockedon:** 5470  

Referenced issues: #5470
Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c10
Original author: https://code.google.com/u/101272611947379421629/

[asmeurer]

**Labels:** -codeinimportedintospreadsheet CodeInImportedIntoMelange  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c11
Original author: https://code.google.com/u/asmeurer@gmail.com/

[asmeurer]

So pyflakes doesn't really warn about many things that shouldn't be fixed, but pylint does.  So if you use pylint, don't bother with things like too short or too long variable names or any "too many..." warnings.  

And of course, if pyflakes says something that turns out to be wrong, don't fix it.  This is just the nature of dynamic languages like Python, that you can not always tell 100% what is happening just by looking at the code.

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c12
Original author: https://code.google.com/u/asmeurer@gmail.com/

[asmeurer]

**Status:** Valid  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c13
Original author: https://code.google.com/u/asmeurer@gmail.com/

[jrioux]

There was work on this at https://github.com/sympy/sympy/pull/738

**Blockedon:** -sympy:2371 sympy:2371  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c14
Original author: https://code.google.com/u/102137482174297837682/

[smichr]

There are still many undefined variables which is bad: this means that an error is waiting to happen in code that is not being tested.

e.g.

sympy/benchmarks/bench_meijerint.py:7: W802 undefined name 'inverse_fourier_transform'
sympy/benchmarks/bench_meijerint.py:8: W802 undefined name 'inverse_laplace_transform'
sympy/benchmarks/bench_meijerint.py:9: W802 undefined name 'inverse_mellin_transform'
sympy/categories/diagram_drawing.py:2082: W802 undefined name 'obj'
sympy/core/tests/test_function.py:231: W802 undefined name 'oo'

And there is a lot of cruft in terms of unused variables which is less critical but could be a good place for beginners to start.

e.g.


sympy/abc.py:1: W402 'Symbol' imported but unused
    it's in an exec

sympy/galgebra/GA.py:2249: W806 redefinition of function 'div' from line 2238
sympy/galgebra/tests/test_GA.py:83: W806 local variable 'Bsq' is assigned to but never used
sympy/galgebra/tests/test_GA.py:116: W806 local variable 'e' is assigned to but never used

I don't know if this issue will ever close. These things crop up like weeds unless the pep8/pyflakes/flake8 tools are not used regularly.

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c15
Original author: https://code.google.com/u/117933771799683895267/

[asmeurer]

**Labels:** -CodeInImportedIntoMelange  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c16
Original author: https://code.google.com/u/asmeurer@gmail.com/

[Krastanov]

**Labels:** CodeInImportedIntoGoogleDocs  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c17
Original author: https://code.google.com/u/100157245271348669141/

[asmeurer]

**Labels:** -CodeInDifficulty-Medium  

Original comment: http://code.google.com/p/sympy/issues/detail?id=1456#c18
Original author: https://code.google.com/u/asmeurer@gmail.com/

[oscarbenjamin]

Since we now use flake8 on Travis and the codebase is free of flake8 warnings I'll close this.