Python 在列表中的位置？
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Position in an list?
提问by kame
I will check if a word exists in a list. How can I show the position of this word?
我将检查列表中是否存在某个单词。我怎样才能显示这个词的位置？
采纳答案by Gabi Purcaru
list = ["word1", "word2", "word3"]
try:
print list.index("word1")
except ValueError:
print "word1 not in list."
This piece of code will print 0, because that's the index of the first occurrence of "word1"
这段代码将打印0，因为这是第一次出现的索引"word1"
回答by Doug T.
回答by Antoine Pelisse
you can use ['hello', 'world'].index('world')
您可以使用 ['hello', 'world'].index('world')
回答by Josh Lee
To check ifan object is in a list, use the inoperator:
要检查，如果对象是在列表中，使用in操作：
>>> words = ['a', 'list', 'of', 'words']
>>> 'of' in words
True
>>> 'eggs' in words
False
Use the indexmethod of a list to find out wherein the list, but be prepared to handle the exception:
使用index列表的方法，找出其中在列表中，但要准备处理异常：
>>> words.index('of')
2
>>> words.index('eggs')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: 'eggs' is not in list
回答by anthony joshua
The following code:
以下代码：
sentence=["I","am","a","boy","i","am","a","girl"]
word="am"
if word in sentence:
print( word, " is in the sentence")
for i, j in enumerate(sentence):
if j == word:
print("'"+word+"'","is in position",i+1)
would produce this output:
会产生这个输出：
"am" is in position 1
"am" is in position 5
This is because in python the indexing starts at 0
这是因为在 python 中索引从 0 开始
Hope this helped!
希望这有帮助！
回答by Feri
Assuming the word is named for example "Monday":
假设这个词被命名为例如“星期一”：
You will need a list as your initial database:
您将需要一个列表作为初始数据库：
myList = ["Monday", "Tuesday", "Monday", "Wednesday", "Thursday", "Friday"]
Then you need to loop through your list one by one to the end using for, next(), iter() and len() function:
然后你需要使用 for、next()、iter() 和 len() 函数一个一个地循环你的列表到最后：
myIter = iter(myList)
for i in range(0, len(myList)):
next_item = next(myIter)
Now while looping, you need to check if the wanted word exists and wherever it exists, print it:
现在在循环时，您需要检查想要的单词是否存在以及它存在的地方，打印它：
if next_item == "Monday":
print(i)
Altogether:
共：
myList = ["Monday", "Tuesday", "Monday", "Wednesday", "Thursday", "Friday"]
myIter = iter(myList)
for i in range(0, len(myList)):
next_item = next(myIter)
if next_item == "Monday":
print(i)
Since there are two Mondays in this list, the result for this example will be: 0 2
由于此列表中有两个星期一，因此此示例的结果将为：0 2
回答by SRG
using enumeration - to find all occurences of given string in list
使用枚举 - 在列表中查找给定字符串的所有出现
listEx=['the','tiger','the','rabit','the','the']
print([index for index,ele in enumerate(listEx) if ele=='the'])
output
输出
[0, 2, 4, 5]
