formulate

Formulate

Easy conversions between different styles of expressions. Formulate currently supports converting between ROOT and numexpr style expressions.

Installation

Install formulate like any other Python package, ideally inside a virtual environment:

pip install formulate

or using conda:

conda install -c conda-forge formulate

(-c conda-forge is only needed if you don't have the conda-forge channel already configured)

Roadmap and releases

For the roadmap, planned features, breaking changes and versioning please see the roadmap.

Usage

API

The most basic usage involves calling from_$BACKEND and then to_$BACKEND, for example when starting with a ROOT style expression:

>>> import formulate
>>> momentum = formulate.from_root("TMath::Sqrt(X_PX**2 + X_PY**2 + X_PZ**2)")
>>> momentum
Call(function='sqrt', arguments=[BinaryOperator(operator='add', left=BinaryOperator(operator='add', left=BinaryOperator(operator='pow', left=Symbol(name='X_PX'), right=Literal(value=2)), right=BinaryOperator(operator='pow', left=Symbol(name='X_PY'), right=Literal(value=2))), right=BinaryOperator(operator='pow', left=Symbol(name='X_PZ'), right=Literal(value=2)))])
>>> momentum.to_numexpr()
'sqrt((((X_PX ** 2) + (X_PY ** 2)) + (X_PZ ** 2)))'
>>> momentum.to_root()
'TMath::Sqrt((((X_PX ** 2) + (X_PY ** 2)) + (X_PZ ** 2)))'

Similarly, when starting with a numexpr style expression:

>>> my_selection = formulate.from_numexpr("(X_PT > 5) & ((Mu_NHits > 3) | (Mu_PT > 10))")
>>> my_selection.to_root()
'((X_PT > 5) && ((Mu_NHits > 3) || (Mu_PT > 10)))'
>>> my_selection.to_numexpr()
'((X_PT > 5) & ((Mu_NHits > 3) | (Mu_PT > 10)))'

CLI

The package also provides a command-line interface for converting expressions between different styles. To use it, simply run the formulate command followed by the input expression and the desired output.

$ formulate --from-root '(A && B) || TMath::Sqrt(A)' --to-numexpr
((A & B) | sqrt(A))

$ formulate --from-numexpr '(A & B) | sqrt(A)' --to-root
((A && B) || TMath::Sqrt(A))

$ formulate --from-root '(A && B) || TMath::Sqrt(1.23) * e_num**1.2 + 5*pi' --variables
A
B

$ formulate --from-root '(A && B) || TMath::Sqrt(1.23) * e_num**1.2 + 5*pi' --named-constants
exp1
pi

$ formulate --from-root '(A && B) || TMath::Sqrt(1.23) * e_num**1.2 + 5*pi' --unnamed-constants
1.23
1.2
5