AttributeError：'str'對象沒有屬性'items'循環時出錯

Question

def printdash(): 
    print('-' * 10) 


# creates a mapping of state to abbreviation 
states = { 
'Oregon': 'OR', 
'Florida': 'FL', 
'California': 'CA', 
'New York': 'NY', 
'Michigan': 'MI' 
} 

# creates a basic set of states with some cities in them 

cities = { 
'CA': 'Sacramento', 
'MI': 'Lansing', 
'FL': 'Tallahasee'} 

# add some more cities to the list 
cities['NY'] = 'Albany' 
cities['OR'] = 'Eugene' 

# Print out some cities 
printdash() 
print('New York State has: ', cities['NY']) 
print('Oregon has: ', cities['OR']) 

# print some states 
printdash() 
print 'Michigan\'s abbreviation is: ' , states['Michigan'] 
print 'Florida\'s abbreviation is: ', states['Florida'] 

# do it by using the state then cities dict. Nested dicts! 
printdash() 
print 'Michigan has: ', cities[states['Michigan']] 
print 'Florifa has: ', cities[states['Florida']] 

# print every states abbreviation 
printdash() 
for states, abbrev in states.items(): 
    print '%s is abbreviated as %s' % (states, abbrev) 
# end 

# print every city in each state 
printdash() 
for abbrev, cities in cities.items(): 
    print '%s has the city %s' % (abbrev, cities) 
# end 

# doing both at the same time 
printdash() 
for state, abbrev in states.items(): 
    print '%s state is abbreviated %s and has city %s' % (state, abbrev, cities[abbrev]) 

每次我運行它，它都會到第54行（最後一個循環），然後引發屬性錯誤標誌。對於我的生活，我無法弄清楚我在做什麼錯誤，因爲其他兩個循環，大多在同一時尚工作設置沒有問題。

查看本網站上的其他解決方案，我發現過去的示例比我能理解的更復雜一些，解決方案似乎比這個非常普遍的案例更具體一些。

Shanks！

Answer 1

當您在第一個循環中將states指定爲目標時，將states的名稱重新指定給states.items()元組的第一項。

這裏是你在做什麼的簡化版本：

>>> i = "hello" 
>>> for i in range(2): print i 
... 
0 
1 
>>> i 
1 

正如你看到的，i是循環後int，而不是一個str，該值是指已經改變。

---

作爲解決方案只需在循環中states重命名爲別的東西，像state或tmp_states。所以：

for state, abbrev in states.items(): 
    print '%s is abbreviated as %s' % (state, abbrev) 

另外做在同樣的模式存在其他循環一樣，像for abbrev, cities in cities.items(): - >for abbrev, city in cities.items()。

Answer 2

線

for states, abbrev in states.items(): 
    print('%s is abbreviated as %s' % (states, abbrev)) 

引起的麻煩。

由於python中循環變量的範圍不限於循環（可以說，它們'泄漏'到您的程序中），因此states將是一個字符串。

您可以通過運行

print(states) 
for states, abbrev in states.items(): 
    print('%s is abbreviated as %s' % (states, abbrev)) 
print(states) 

調試這將打印

---------- 
{'California': 'CA', 'Michigan': 'MI', 'New York': 'NY', 'Florida': 'FL', 'Oregon': 'OR'} 
California is abbreviated as CA 
Michigan is abbreviated as MI 
New York is abbreviated as NY 
Florida is abbreviated as FL 
Oregon is abbreviated as OR 
Oregon 

此外，你應該檢查你的print使用。請堅持印刷說明的一種版本，要麼print 'foo'或print('foo')。第二個用法（作爲函數）是唯一能在Python 3.X中工作的用法。

Answer 3

「城市」和「州」在第一個和第二個循環中被覆蓋。使用不同的變量名應該修復它。