假设我想在 [10^-20, 0.1] 范围内抽取一个随机数，我该怎么做？
如果我使用 numpy.random.uniform，我似乎不会低于 10^-2:
In [2]: np.random.uniform(0.1, 10**(-20))
Out[2]: 0.02506361878539856
In [3]: np.random.uniform(0.1, 10**(-20))
Out[3]: 0.04035553250149768
In [4]: np.random.uniform(0.1, 10**(-20))
Out[4]: 0.09801074888377342
In [5]: np.random.uniform(0.1, 10**(-20))
Out[5]: 0.09778150831277296
In [6]: np.random.uniform(0.1, 10**(-20))
Out[6]: 0.08486347093110456
In [7]: np.random.uniform(0.1, 10**(-20))
Out[7]: 0.04206753781952958
或者我可以生成一个数组，而不是像:
In [44]: fac = np.linspace(10**(-20),10**(-1),100)
In [45]: fac
Out[45]:
array([ 1.00000000e-20, 1.01010101e-03, 2.02020202e-03,
3.03030303e-03, 4.04040404e-03, 5.05050505e-03,
6.06060606e-03, 7.07070707e-03, 8.08080808e-03,
9.09090909e-03, 1.01010101e-02, 1.11111111e-02,
1.21212121e-02, 1.31313131e-02, 1.41414141e-02,
1.51515152e-02, 1.61616162e-02, 1.71717172e-02,
1.81818182e-02, 1.91919192e-02, 2.02020202e-02,
2.12121212e-02, 2.22222222e-02, 2.32323232e-02,
2.42424242e-02, 2.52525253e-02, 2.62626263e-02,
2.72727273e-02, 2.82828283e-02, 2.92929293e-02,
3.03030303e-02, 3.13131313e-02, 3.23232323e-02,
3.33333333e-02, 3.43434343e-02, 3.53535354e-02,
3.63636364e-02, 3.73737374e-02, 3.83838384e-02,
3.93939394e-02, 4.04040404e-02, 4.14141414e-02,
4.24242424e-02, 4.34343434e-02, 4.44444444e-02,
4.54545455e-02, 4.64646465e-02, 4.74747475e-02,
4.84848485e-02, 4.94949495e-02, 5.05050505e-02,
5.15151515e-02, 5.25252525e-02, 5.35353535e-02,
5.45454545e-02, 5.55555556e-02, 5.65656566e-02,
5.75757576e-02, 5.85858586e-02, 5.95959596e-02,
6.06060606e-02, 6.16161616e-02, 6.26262626e-02,
6.36363636e-02, 6.46464646e-02, 6.56565657e-02,
6.66666667e-02, 6.76767677e-02, 6.86868687e-02,
6.96969697e-02, 7.07070707e-02, 7.17171717e-02,
7.27272727e-02, 7.37373737e-02, 7.47474747e-02,
7.57575758e-02, 7.67676768e-02, 7.77777778e-02,
7.87878788e-02, 7.97979798e-02, 8.08080808e-02,
8.18181818e-02, 8.28282828e-02, 8.38383838e-02,
8.48484848e-02, 8.58585859e-02, 8.68686869e-02,
8.78787879e-02, 8.88888889e-02, 8.98989899e-02,
9.09090909e-02, 9.19191919e-02, 9.29292929e-02,
9.39393939e-02, 9.49494949e-02, 9.59595960e-02,
9.69696970e-02, 9.79797980e-02, 9.89898990e-02,
1.00000000e-01])
并从该数组中随机选择一个元素，但无论如何我都想澄清第一个选项是否可行，因为我可能会遗漏一些明显的东西。
请您参考如下方法:
您需要仔细考虑您正在做的事情。您要求在几乎 0.0 和 0.1 之间均匀分布。平均结果为 0.05。这正是你得到的。您似乎想要指数的随机分布。
以下可能会做你想做的事:
import random
def rnd():
exp = random.randint(-19, -1)
significand = 0.9 * random.random() + 0.1
return significand * 10**exp
[rnd() for _ in range(20)]
最低可能值是 exp=-19和 significand=0.1给予 0.1*10**-19 = 1**-20 .最高可能值是 exp=-1和 significand=1.0给予 1.0*10**-1 = 0.1 .
注意:从技术上讲，significand只能将 1.0 作为 random() is bounded to [0.0, 1.0)，即包含0.0，不包含1.0。
输出:
[2.3038280595190108e-11,
0.02658855644891981,
4.104572641101877e-11,
3.638231824527544e-19,
6.220040206106022e-17,
7.207472203268789e-06,
6.244626749598619e-17,
2.299282102612733e-18,
0.0013251357609258432,
3.118805901868378e-06,
6.585606992344938e-05,
0.005955900790586139,
1.72779538837876e-08,
7.556972406280229e-13,
3.887023124444594e-15,
0.0019965330694999488,
1.7732147730252207e-08,
8.920398286274208e-17,
4.4422869312622194e-08,
2.4815949527034027e-18]
请参阅维基百科上的“scientific notation”以了解有效数和指数的定义。
