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:

pip install --user formulate

or similar (use sudo, virtualenv, or conda if you wish).

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
Expression<SQRT>(Expression<ADD>(Expression<POW>(Variable(X_PX), UnnamedConstant(2)), Expression<POW>(Variable(X_PY), UnnamedConstant(2)), Expression<POW>(Variable(X_PZ), UnnamedConstant(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))'