def FiniteRV(density, symbol=None):
"""
Create a Finite Random Variable given a dict representing the density.
Returns a RandomSymbol.
>>> from sympy.stats import FiniteRV, P, E
>>> density = {0: .1, 1: .2, 2: .3, 3: .4}
>>> X = FiniteRV(density)
>>> E(X)
2.00000000000000
>>> P(X>=2)
0.700000000000000
"""
return create_SingleFinitePSpace(density, symbol).value
def __new__(cls, sides=6, symbol=None):
density = dict((i,Rational(1,sides)) for i in range(1,sides+1))
return create_SingleFinitePSpace(density, symbol, cls)
def __new__(cls, p, a, b, symbol=None):
a, b, p = map(sympify, (a, b, p))
density = {a:p, b:(1-p)}
return create_SingleFinitePSpace(density, symbol, cls)
def __new__(cls, items, symbol=None):
density = dict((sympify(item), Rational(1, len(items)))
for item in items)
return create_SingleFinitePSpace(density, symbol, cls)
def __new__(cls, N, m, n, symbol=None):
N, m, n = map(sympify, (N, m, n))
density = dict((k, binomial(m, k) * binomial(N-m, n-k) / binomial(N, n))
for k in range(max(0, n+m-N), min(m, n) + 1))
return create_SingleFinitePSpace(density, symbol, cls)
def __new__(cls, n, p, succ=1, fail=0, symbol=None):
n, p, succ, fail = map(sympify, (n, p, succ, fail))
density = dict((k*succ + (n-k)*fail,
binomial(n, k) * p**k * (1-p)**(n-k)) for k in range(0, n+1))
return create_SingleFinitePSpace(density, symbol, cls)
def __new__(cls, p, succ=1, fail=0, symbol=None):
succ, fail, p = map(sympify, (succ, fail, p))
density = {succ:p, fail:(1-p)}
return create_SingleFinitePSpace(density, symbol, cls)
