1 from __future__ import absolute_import, division
7 def median(x, use_float=True):
8 # there exist better algorithms...
11 raise ValueError('empty sequence!')
12 left = (len(y) - 1)//2
14 sum = y[left] + y[right]
39 def clip(x, (low, high)):
55 raise ValueError('p must be in the interval (0.0, 1.0]')
58 return int(math.log1p(-random.random()) / math.log1p(-p)) + 1
60 def add_dicts(*dicts):
63 for k, v in d.iteritems():
64 res[k] = res.get(k, 0) + v
65 return dict((k, v) for k, v in res.iteritems() if v)
70 while x >= 100000 and count < len(prefixes) - 2:
73 s = '' if count == 0 else prefixes[count - 1]
74 return '%i' % (x,) + s
76 perfect_round = lambda x: int(x + random.random())
95 y = 1.0 - (((((a5*t + a4)*t) + a3)*t + a2)*t + a1)*t*math.exp(-x*x)
96 return sign*y # erf(-x) = -erf(x)
98 def find_root(y_over_dy, start, steps=10, bounds=(None, None)):
100 for i in xrange(steps):
101 guess = guess - y_over_dy(guess)
102 if bounds[0] is not None and guess < bounds[0]: guess = bounds[0]
103 if bounds[1] is not None and guess > bounds[1]: guess = bounds[1]
107 return find_root(lambda x: (erf(x) - z)/(2*math.e**(-guess**2)/math.sqrt(math.pi)), 0)
110 from scipy import special
112 print 'Install SciPy for more accurate confidence intervals!'
113 def binomial_conf_interval(x, n, conf=0.95):
115 return (1-conf)/2, 1-(1-conf)/2
116 # approximate - Wilson score interval
117 z = math.sqrt(2)*ierf(conf)
120 topb = z * math.sqrt(p*(1-p)/n + z**2/4/n**2)
122 return (topa - topb)/bottom, (topa + topb)/bottom
124 def binomial_conf_interval(x, n, conf=0.95):
126 left = random.random()*(1 - conf)
127 return left, left + conf
128 dkpdf = lambda p: ((x*p**(x-1) * (1-p)**(n-x) - p**x * (n-x)*(1-p)**(n-x-1)) \
129 if p != 0 else {0: -n, 1: 1}.get(x, 0)*special.beta(x+1, n-x+1)) \
130 if p != 1 else {n-1: -1, n: n}.get(x, 0)*special.beta(x+1, n-x+1)
132 right = special.betaincinv(x+1, n-x+1, special.betainc(x+1, n-x+1, left) + conf)
133 l_pdf, r_pdf = left**x*(1-left)**(n-x), right**x*(1-right)**(n-x)
134 return (r_pdf - l_pdf)*r_pdf/(dkpdf(right)*l_pdf - dkpdf(left)*r_pdf)
135 left_max = special.betaincinv(x+1, n-x+1, 1 - conf)
136 left = find_root(f, left_max/2, 8, (0, left_max))
137 return left, special.betaincinv(x+1, n-x+1, special.betainc(x+1, n-x+1, left) + conf)
139 def binomial_conf_center_radius(x, n, conf=0.95):
140 left, right = binomial_conf_interval(x, n, conf)
142 return (left+right)/2, (right-left)/2
144 return p, max(p - left, right - p)
148 return __builtin__.reversed(x)
150 return reversed(list(x))
152 class Object(object):
153 def __init__(self, **kwargs):
154 for k, v in kwargs.iteritems():
157 def add_tuples(res, *tuples):
159 if len(t) != len(res):
160 raise ValueError('tuples must all be the same length')
161 res = tuple(a + b for a, b in zip(res, t))
164 def flatten_linked_list(x):
169 def weighted_choice(choices):
170 choices = list((item, weight) for item, weight in choices)
171 target = random.randrange(sum(weight for item, weight in choices))
172 for item, weight in choices:
176 raise AssertionError()
178 if __name__ == '__main__':
182 print a, format(a) + 'H/s'
183 a = a * random.randrange(2, 5)