生日悖论列表是非类型(Birthday Paradox List is nonetype)

def make_bd(n, r):
"""Generates (r) numbers of birthdays in a range (n)."""
import random
t = [random.randrange(n) for i in range(r)]
print (t)

def has_dupe(test):
"""Here I test to see if I can detect a duplicate birthday.
This is based on problem #4."""

d = []
count = 0
for number in test:
if number in d:
count = count + 1
d.append(number)
if count >= 1:
return True
return False

def dupebd(n,r,t):
count_dupe = 0
for i in range(n):
if has_dupe(make_bd(r,t)):
count_dupe = count_dupe + 1
print (float(count)/n)

dupebd(50,365,23)

>>> has_dupe(make_bd(50,6))
[13, 3, 8, 29, 34, 44]
Traceback (most recent call last):
File "<pyshell#45>", line 1, in <module>
has_dupe(make_bd(50,6))
File "<pyshell#44>", line 7, in has_dupe
for number in test:
TypeError: 'NoneType' object is not iterable

I'm trying to solve the Birthday Paradox with Python. I'm close but the last piece has me at a loss. I'm using random to generate a list of numbers given a range and number of items to create. That works.

I then check to see if a list (generated above) has duplicates. That works.

I then try to generate a given (n) of lists. Here is where I run into trouble. It generates one list then returns "NoneType" is not iterable. What puzzles me is, the list is generated but Python is not seeing it as a list.

Here's the code:

def make_bd(n, r):
"""Generates (r) numbers of birthdays in a range (n)."""
import random
t = [random.randrange(n) for i in range(r)]
print (t)

def has_dupe(test):
"""Here I test to see if I can detect a duplicate birthday.
This is based on problem #4."""

d = []
count = 0
for number in test:
if number in d:
count = count + 1
d.append(number)
if count >= 1:
return True
return False

def dupebd(n,r,t):
count_dupe = 0
for i in range(n):
if has_dupe(make_bd(r,t)):
count_dupe = count_dupe + 1
print (float(count)/n)

dupebd(50,365,23)

Here's the result:

>>> has_dupe(make_bd(50,6))
[13, 3, 8, 29, 34, 44]
Traceback (most recent call last):
File "<pyshell#45>", line 1, in <module>
has_dupe(make_bd(50,6))
File "<pyshell#44>", line 7, in has_dupe
for number in test:
TypeError: 'NoneType' object is not iterable

最满意答案

return t

In line 5 you print t but do not return it, so that make_bd returns None. Change the line to

return t
2012-04-29

解析表时Python处理NoneType(Python handling NoneType when parsing tables)

itertools.zip_longest接受可选的fillvalue参数。 如果提供，则使用它而不是None ： >>> list(itertools.zip_longest([1, 2, 3], [4, 5])) [(1, 4), (2, 5), (3, None)] >>> list(itertools.zip_longest([1, 2, 3], [4, 5], fillvalue='NULL')) [(1, 4), (2, 5), (3, 'NULL')] 您可以提供空行（NULL值

AttributeError：'NoneType'对象没有属性'findChildren'（美丽的汤）(AttributeError: 'NoneType' object has no attribute 'findChildren' (Beautiful Soup))

soup.find('ul',{'class': "tags"})返回None 。 如果要在列表推导中使用它，则需要在使用它们之前过滤掉None值。 有一个技巧，你可以将值放在列表中，以便过滤它： tags_dict['tags'] = [child.text for tag in [soup.find('ul',{'class': "tags"})] if tag fo

创建元组列表，元组元素作为输入(Create list of tuples , tuple elements taken as Input)

append()函数不返回附加列表，它返回NoneType因为它执行附加到位 ，因此您只需更改行： l=l.append(tuple(i)) 至： l.append(tuple(i)) 这应该工作。 The append() function does not return an appended list, it returns a NoneType because it performs the append in place, so you can simply change the