Python PDF示例

示例#1

def test_PDF():
    a = Symbol('a', positive=True)
    x = Symbol('x', real=True)
    exponential = PDF(exp(-x / a), (x, 0, oo))
    exponential = exponential.normalize()
    assert exponential.pdf(x) == 1 / a * exp(-x / a)
    assert exponential.cdf(x) == 1 - exp(-x / a)
    assert exponential.mean == a
    assert exponential.variance == a**2
    assert exponential.stddev == a

示例#2

文件： test_statistics.py 项目： jcockayne/sympy-rkern

def test_PDF():
    a = Symbol('a', positive=True)
    x = Symbol('x', real=True)
    exponential = PDF(exp(-x/a), (x,0,oo))
    exponential = exponential.normalize()
    assert exponential.pdf(x) == 1/a*exp(-x/a)
    assert exponential.cdf(x) == 1 - exp(-x/a)
    assert exponential.mean == a
    assert exponential.variance == a**2
    assert exponential.stddev == a

示例#3

文件： test_statistics.py 项目： Acebulf/sympy

def test_PDF():
    a = Symbol('a', positive=True)
    x = Symbol('x', real=True)
    exponential = PDF(exp(-x/a), (x, 0, oo))
    exponential = exponential.normalize()
    assert exponential.pdf(x) == 1/a*exp(-x/a)
    assert exponential.cdf(x) == 1 - exp(-x/a)
    assert exponential.mean == a
    assert exponential.variance == a**2
    assert exponential.stddev == a
    exponential = PDF(exp(-x/a), x)
    assert exponential.pdf(x) == exp(-x/a)
    assert exponential.cdf(x) == -a*exp(-x/a) + oo
    assert exponential.mean == -oo
    exponential = PDF(1, (x, 1, 2))
    assert exponential.normalize() == exponential
    assert exponential._get_stddev() == sqrt(3)/6
    assert exponential._get_stddev() == sqrt(3)/6
    #This test is intentionally repeated to test PDF._get_stddev() properly.
    exponential = exponential.transform(x, x)
    assert exponential.pdf(x) == 1
    assert exponential.cdf(x) == x - 1

示例#4

def test_PDF():
    a = Symbol('a', positive=True)
    x = Symbol('x', real=True)
    exponential = PDF(exp(-x / a), (x, 0, oo))
    exponential = exponential.normalize()
    assert exponential.pdf(x) == 1 / a * exp(-x / a)
    assert exponential.cdf(x) == 1 - exp(-x / a)
    assert exponential.mean == a
    assert exponential.variance == a**2
    assert exponential.stddev == a
    exponential = PDF(exp(-x / a), x)
    assert exponential.pdf(x) == exp(-x / a)
    assert exponential.cdf(x) == -a * exp(-x / a) + oo
    assert exponential.mean == -oo
    exponential = PDF(1, (x, 1, 2))
    assert exponential.normalize() == exponential
    assert exponential._get_stddev() == sqrt(3) / 6
    assert exponential._get_stddev() == sqrt(3) / 6
    #This test is intentionally repeated to test PDF._get_stddev() properly.
    exponential = exponential.transform(x, x)
    assert exponential.pdf(x) == 1
    assert exponential.cdf(x) == x - 1