ScoDoc/app/scodoc/sco_formulas.py

# -*- mode: python -*-
# -*- coding: utf-8 -*-

##############################################################################
#
# Gestion scolarite IUT
#
# Copyright (c) 1999 - 2022 Emmanuel Viennet.  All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
#   Emmanuel Viennet      emmanuel.viennet@viennet.net
#
##############################################################################

"""Une classe "vecteur" pour les formules utilisateurs de calcul des moyennes
"""

import operator
from functools import reduce


def cmp(x, y):
    """
    Replacement for built-in function cmp that was removed in Python 3
    Compare the two objects x and y and return an integer according to
    the outcome. The return value is negative if x < y, zero if x == y
    and strictly positive if x > y.
    """
    return (x > y) - (x < y)


class NoteVector(object):
    """Vecteur de notes (ou coefficients) utilisé pour les formules définies par l'utilisateur.
    Les éléments sont accessibles soit par index v[i], soit par leur nom v['nom'] s'il en ont un.
    Les éléments sont toujours numériques (float). Les valeurs non numériques ('NI', ...) sont
    considérées comme nulles (0.0).
    """

    def __init__(self, *args, **kwargs):
        if args:
            self.v = list(map(float, args))  # cast to list of float
        elif "v" in kwargs:
            v = kwargs["v"]
            if not isinstance(v, NoteVector):
                # replace all non-numeric values by zeroes: (formulas should check cmask !)
                for i in range(len(v)):
                    try:
                        v[i] = float(v[i])
                    except ValueError:
                        v[i] = 0.0
            self.v = v
        else:
            self.v = []
        self.name_idx = {}  # { name : index in vector }

    def __len__(self):
        return len(self.v)

    def __getitem__(self, i):
        try:
            return self.v[i]
        except:
            if isinstance(i, str):
                return self.v[self.name_idx[i]]
            else:
                raise IndexError("index %s out of range" % i)

    def append(self, value, name=None):
        """Append a value to the vector."""
        try:
            v = float(value)
        except ValueError:
            v = 0.0
        self.v.append(v)
        if name:
            self.name_idx[name] = len(self.v) - 1

    def __repr__(self):
        return "NVector(%s, name_idx=%s)" % (str(self.v), self.name_idx)

    def __add__(self, x):
        return binary_op(self.v, x, operator.add)

    __radd__ = __add__

    def __sub__(self, x):
        return binary_op(self.v, x, operator.sub)

    def __rsub__(self, x):
        return binary_op(x, self.v, operator.sub)

    def __mul__(self, x):
        return binary_op(self.v, x, operator.mul)

    __rmul__ = __mul__

    def __div__(self, x):
        return binary_op(self.v, x, operator.truediv)

    __truediv__ = __div__  # for py3

    def __floordiv__(self, x):
        return binary_op(self.v, x, operator.floordiv)

    def __rdiv__(self, x):
        return binary_op(x, self.v, operator.truediv)

    __rtruediv__ = __rdiv__  # for py3

    def __rfloordiv__(self, x):
        return binary_op(x, self.v, operator.floordiv)


def is_scalar(x):
    return isinstance(x, (float, int))


def binary_op(x, y, op):
    if is_scalar(x):
        if is_scalar(y):
            x, y = [x], [y]
        else:
            x = [x] * len(y)
    if is_scalar(y):
        y = [y] * len(x)

    if len(x) != len(y):
        raise ValueError("vectors sizes don't match")

    return NoteVector(v=[op(a, b) for (a, b) in zip(x, y)])


def dot(u, v):
    """Dot product between 2 lists or vectors"""
    return sum([x * y for (x, y) in zip(u, v)])


def ternary_op(cond, a, b):
    if cond:
        return a
    else:
        return b


def geometrical_mean(v, w=None):
    """Geometrical mean of v, with optional weights w"""
    if w is None:
        return pow(reduce(operator.mul, v), 1.0 / len(v))
    else:
        if len(w) != len(v):
            raise ValueError("vectors sizes don't match")
        vw = [pow(x, y) for (x, y) in zip(v, w)]
        return pow(reduce(operator.mul, vw), 1.0 / sum(w))


# Les builtins autorisées dans les formules utilisateur:
formula_builtins = {
    "V": NoteVector,
    "dot": dot,
    "max": max,
    "min": min,
    "abs": abs,
    "cmp": cmp,
    "len": len,
    "map": map,
    "pow": pow,
    "reduce": reduce,
    "round": round,
    "sum": sum,
    "ifelse": ternary_op,
    "geomean": geometrical_mean,
}

# v = NoteVector(1,2)
# eval("max(4,5)", {'__builtins__': formula_builtins, {'x' : 1, 'v' : NoteVector(1,2) }, {})


def eval_user_expression(expression, variables):
    """Evalue l'expression (formule utilisateur) avec les variables (dict) données."""
    variables["__builtins__"] = formula_builtins
    # log('Evaluating %s with %s' % (expression, variables))
    # may raise exception if user expression is invalid
    return eval(expression, variables, {})  # this should be safe