2017年2月6日 星期一

Pyhon 裡面的Random與Pandas的Random

在看教學文章時,常常搞不清楚random.random , random.rand , random.randn 一堆看似類似但卻又不太一樣的函數。為了學的踏實點,就去了解了下: 


import random 
# random just return one object
import numpy as np 
# use numpy.random  will return one or an array object
 
a = random.random()
# return one object
aa = random.random(10)
# fail, because it only return one object
 
b = random.randint(10,20)
# return an int object between 10~20
 
c = random.uniform(10,20)
#return an object between 10~20
 
d = random.randrange(10,20,3)
#return an int object in range 10~20 (such 10, 13,16,19)
 
e = random.choice(('pass','fail','null'))
# random choice one object
 
 
 
A = np.random.random()
# same as random.random()
 
AA = np.random.random(10) # 更新:不建議這樣用,因為np.random.random(10,4)的矩陣會回報錯
# can return an array
 
G = np.random.rand(10)   # 更新:np.random.rand(10,4)的矩陣仍可以過 所以用矩陣的話寫rand就好
# same as np.random.random(10)
 
F = np.random.randn()
# return an normal distribution or Gaussian distribution object in random
FF=  np.random.randn(10)
# return an normal distribution or Gaussian distribution array in random
 
 
 
B = np.random.randint(10,20)
# same as random.randint(10,20)
 
CC = np.random.uniform(10,20)
# same as random.uniform(10,20)
 
DD = np.random.randrange(10,20,3)
# fail, becauseno attribute randrange in np.random



總的來說,如果要出一個隨機數,就用random的就好。
如果需要用到array或矩陣的再引用np.random 免得搞混

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