[PYTHON] Pseudo-random number generation and random sampling

Generate random numbers with standard modules

Python has a random module as a standard library, which can generate random numbers with various distributions. It has the following main features.

Available major distributions such as uniform, normal, lognormal, negative exponential, gamma and beta.
Implemented in C as a random number generator [Mersenne Twister (MT)](http://en.wikipedia.org/wiki/%E3%83%A1%E3%83%AB%E3%82%BB%E3 % 83% B3% E3% 83% 8C% E3% 83% BB% E3% 83% 84% E3% 82% A4% E3% 82% B9% E3% 82% BF) is used.
You can also subclass Random and create your own random number generator.

Random number generation example

In NumPy's Random Sample Function (http://docs.scipy.org/doc/numpy/reference/generated/numpy.random.random_sample.html#numpy.random.random_sample), it's a floating point number or an integer (http) You can generate random numbers at //docs.scipy.org/doc/numpy/reference/generated/numpy.random.random_integers.html#numpy.random.random_integers).

np.random.random_sample((5,))
#=> array([ 0.80055457,  0.19615444,  0.50532311,  0.48243283,  0.56227889])

np.random.random_sample((5,2))
#=>
# array([[ 0.59495428,  0.56194628],
#        [ 0.93675326,  0.88873404],
#        [ 0.98967746,  0.2319963 ],
#        [ 0.20625308,  0.76956028],
#        [ 0.7870824 ,  0.30181687]])

Random sorting of data frames

Random permutation of data frames is possible by using permutation I will.

df = pd.DataFrame(np.arange(10*4).reshape(10,4))
sampler = np.random.permutation(5)
#=> array([0, 2, 1, 3, 4])

df.take(sampler)
#=>
#     0   1   2   3
# 0   0   1   2   3
# 2   8   9  10  11
# 1   4   5   6   7
# 3  12  13  14  15
#4  16  17  18  19

np.random.permutation(len(df))
#=> array([6, 7, 8, 3, 9, 4, 2, 1, 0, 5])

Pull playing cards

Consider a cord that draws 10 cards from a pile of 52 playing cards. You can shuffle using random.shuffle, so you can subtract any number from here.

#Prepare a pile of playing cards
deck = list(
    itertools.product(list(range(1, 14)),
                      ['spade', 'heart', 'Diamond', 'club']))

random.shuffle(deck) #Shuffle the deck

print("Card drawn:")
for i in range(10): #Draw 10 cards
    print(deck[i][1] + "of" + str(deck[i][0]))

#=>Card drawn:
#Diamond 6
#Club 3
#10 of hearts
#Diamond 12
#8 of spades
#Club 13
#Diamond 13
#5 of spades
#12 of hearts
#Diamond 7

Since there are only 52 playing cards, random.shuffle (53) will result in IndexError.