Python Equation Calculation Research

Packages

Sympy

http://docs.sympy.org/

More suited for equation solving, not string based

Equation

https://github.com/alphaomega-technology/Equation https://pypi.python.org/pypi/Equation/1.0

Exceptions are pretty unhelpful.

Requires pre-parsing of parameter tokens into simple variables (chokes on <Production capacity>, needs x instead).

Has some latex output support, would still need to figure out how to interpolate meaningful variables names.

Operators & functions

/
%
^
**
&&
||
&
|
</>
&|
|&
==
=
~
!~
!=
<>
<
<
<=
=
=<
=>
<~
~
~<
~>
!
abs
sum
prod
floor
ceil
round
sin
cos
tan
re
im
sqrt
pi
NaN

In [22]: Expression("x + sum(3,4,y)", ["x", "y"])(1, 5)
Out[22]: 13

py-expression-eval

https://github.com/AxiaCore/py-expression-eval

Light-weight. And the logical operators are a bit confusing.

Requires pre-parsing of parameter tokens into simple variables (chokes on <Production capacity>, needs x instead).

Exceptions for:

invalid expression
unexpected operator
unexpected number
unexpected string
unexpected constant
unexpected function
unexpected operator
unexpected variable
unexpected parenthesis
unmatched parenthesis

Operations & functions

+: add
-: sub
-: neg
*: mul
/: div
%: mod
^: pow
,: append
||: concat
==: equal
!=: notEqual
>: greaterThan
<: lessThan
>=: greaterThanEqual
<=: lessThanEqual
sin: sin
cos: cos
tan: tan
asin: asin
acos: acos
atan: atan
sqrt: sqrt
log: log
abs: abs
ceil: ceil
floor: floor
round: round
exp: exp
and: and
or: or
random: random
fac: fac
min: min
max: max
pyt: pyt
pow: pow
atan2: atan2
concat: concat
if (possible?)
E: e
PI: pi

In [9]: parser.parse('if(a >= 5, b*2, b-1)').evaluate({'a': 2, 'b': 10})
Out[9]: 9.0

In [10]: parser.parse('if(a >= 5, b*2, b-1)').evaluate({'a': 6, 'b': 10})
Out[10]: 20.0

pytexit

https://github.com/erwanp/pytexit

Converts python expressions to LaTeX formula.

But we're not supporting python expressions. :-(

Automatic LaTeX conversion might be really hard unless we can tack it onto the parse/evaluate library.

An alternative would be to have a live-updating field for the LaTeX version of the formula.