create or adapt or include a units package

[jasongrout]

See this sage-wiki page for some ideas.

Here are three possibilities:

• ScientificPython's PhysicalQuantities package: http://dirac.cnrs-orleans.fr/ScientificPython/ScientificPythonManual/Scientific.Physics.PhysicalQuantities-module.html

It looks like this package is part of an actively maintained library, ScientificPython (http://dirac.cnrs-orleans.fr/plone/software/scientificpython/). Here is a link for a printing package for this module: http://python.net/crew/bhoel/PyLaTeX-0.2/html/PyLaTeX.UnitPrint.html

• Unum: http://home.scarlet.be/be052320/Unum.html

It looks like this package is dead; last release was in 2005. It is GPL.

• The Pyre units package (http://www.cacr.caltech.edu/projects/pyre/). This was last updated in 2005, I think (you have to check out pythia 0.8).

• The enthought units package (which is apparently based on the pyre package), as well as the blockcanvas unit functions.

A thread about adding a units package to scipy: http://projects.scipy.org/pipermail/scipy-user/2005-March/004263.html

Another thread: http://aspn.activestate.com/ASPN/Mail/Message/scipy-user/3176352

Another page in a book mentioning two packages: http://books.google.com/books?id=j7QbD83-h8AC&pg=PA157&lpg=PA157&dq=python+physicalquantities&source=web&ots=C-JZyCFWn2&sig=x62bQ0jWyQerBGAvgJOBQuMQeWM&hl=en&sa=X&oi=book_result&resnum=10&ct=result

A recent (July 2008!) trac ticket about the enthought units package: https://svn.enthought.com/enthought/ticket/1524 Related checkins seem to include: https://svn.enthought.com/enthought/changeset/21093

Apparently the enthought units code is undergoing refactorization. See https://mail.enthought.com/pipermail/enthought-dev/2008-July/015717.html

I'd say we ought to keep our eye (or help out with) the enthought package refactorization.

Component: basic arithmetic

Author: David Ackerman, William Stein

Reviewer: Dan Drake

Merged: sage-4.4.alpha0

Issue created by migration from https://trac.sagemath.org/ticket/3852

[jasongrout]

comment:1

Okay, so that was four projects!

[jasongrout]

comment:3

yet another project recently started:

http://sourceforge.net/mailarchive/forum.php?thread_name=200808051930.57498.dsdale24%40gmail.com&forum_name=matplotlib-devel

[williamstein]

comment:5

Attachment: trac_3852.patch.gz

FIRST REFEREE REPORT on trac_3852.patch:

1. The doctest coverage is still very bad (38%):

wstein@sage:~/build/sage-4.1.1$ ./sage -coverage devel/sage/sage/symbolic/units.py 
----------------------------------------------------------------------
devel/sage/sage/symbolic/units.py
ERROR: Please define a s == loads(dumps(s)) doctest.
SCORE devel/sage/sage/symbolic/units.py: 38% (5 of 13)

Missing documentation:
         * evalunitdict():
         * unit_derivations_expr(v):
         * _sage_doc_(self):
         * str_to_unit(name):
         * __init__(self, data):
         * trait_names(self):
         * __getattr__(self, name):


Missing doctests:
         * vars_in_str(s):


Possibly wrong (function name doesn't occur in doctests):
         * convert_temperature(expr, target):

----------------------------------------------------------------------

2. The new code fails numerous doctests:

        sage -t  devel/sage/sage/symbolic/units.py # 4 doctests failed
        sage -t  devel/sage/sage/symbolic/expression.pyx # 2 doctests failed

The actual failures:

**********************************************************************
File "/scratch/wstein/build/sage-4.1.1/devel/sage/sage/symbolic/expression.pyx", line 5399:
    sage: (units.pressure.pascal*units.si_prefixes.kilo).convert(units.pressure.pounds_per_square_inch)
Exception raised:
    Traceback (most recent call last):
      File "/scratch/wstein/build/sage-4.1.1/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/scratch/wstein/build/sage-4.1.1/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/scratch/wstein/build/sage-4.1.1/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_137[10]>", line 1, in <module>
        (units.pressure.pascal*units.si_prefixes.kilo).convert(units.pressure.pounds_per_square_inch)###line 5399:
    sage: (units.pressure.pascal*units.si_prefixes.kilo).convert(units.pressure.pounds_per_square_inch)
      File "expression.pyx", line 5424, in sage.symbolic.expression.Expression.convert (sage/symbolic/expression.cpp:21250
)
      File "/scratch/wstein/build/sage-4.1.1/local/lib/python/site-packages/sage/symbolic/units.py", line 1064, in convert
        expr = expr.subs(z)
      File "expression.pyx", line 2777, in sage.symbolic.expression.Expression.substitute (sage/symbolic/expression.cpp:13
700)
      File "expression.pyx", line 1517, in sage.symbolic.expression.Expression.coerce_in (sage/symbolic/expression.cpp:959
1)
      File "parent_old.pyx", line 331, in sage.structure.parent_old.Parent._coerce_ (sage/structure/parent_old.c:4673)
      File "parent.pyx", line 429, in sage.structure.parent.Parent.coerce (sage/structure/parent.c:4806)
    TypeError: no canonical coercion from <type 'str'> to Symbolic Ring

...

File "/scratch/wstein/build/sage-4.1.1/devel/sage/sage/symbolic/units.py", line 31:
    e: units.force.dyne?
Exception raised:
    Traceback (most recent call last):
      File "/scratch/wstein/build/sage-4.1.1/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/scratch/wstein/build/sage-4.1.1/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/scratch/wstein/build/sage-4.1.1/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_0[6]>", line 1
         units.force.dyne?###line 31:
    e: units.force.dyne?
                         ^
     SyntaxError: invalid syntax
**********************************************************************
File "/scratch/wstein/build/sage-4.1.1/devel/sage/sage/symbolic/units.py", line 52:

**********************************************************************
File "/scratch/wstein/build/sage-4.1.1/devel/sage/sage/symbolic/units.py", line 52:
    e: t.convert(unit.charge.coulomb)
Expected:
    Traceback (most recent call last):
    ...
    ValueError: Incompatible units
Got:
    Traceback (most recent call last):
      File "/scratch/wstein/build/sage-4.1.1/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/scratch/wstein/build/sage-4.1.1/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/scratch/wstein/build/sage-4.1.1/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_0[11]>", line 1, in <module>
        t.convert(unit.charge.coulomb)###line 52:
    e: t.convert(unit.charge.coulomb)
    NameError: name 'unit' is not defined


...

[sagetrac-edrex]

comment:6

Google also turns up this existing module: http://www.inference.phy.cam.ac.uk/dimpy/

[sagetrac-edrex]

comment:7

dimpy helped me with my e&m hw. positive review :)

[jasongrout]

comment:8

Do you mean that tongue-in-cheek, or do you mean that you've gone through and made sure all of the objections above were taken care of?