For lists, the method list.index(x)
returns the index in the list of the first item whose value is x
. But if I want to look inside the list items, and not just at the whole items, how do I make the most Pythoninc method for this?
对于列表,方法list.index(x)返回值为x的第一个项的列表中的索引。但是如果我想查看列表项,而不仅仅是整个项目,我如何为此创建最多的Pythoninc方法?
For example, with
例如,用
l = ['the cat ate the mouse',
'the tiger ate the chicken',
'the horse ate the straw']
this function would return 1
provided with the argument tiger
.
这个函数将返回1与参数tiger一起提供。
8 个解决方案
#1
27
A non-slicky method:
一种非流畅的方法:
def index_containing_substring(the_list, substring):
for i, s in enumerate(the_list):
if substring in s:
return i
return -1
#2
4
With a one-liner:
使用单线程:
index = [idx for idx, s in enumerate(l) if 'tiger' in s][0]
#3
3
Variation of abyx solution (optimised to stop when the match is found)
abyx解决方案的变化(优化为在找到匹配时停止)
def first_substring(strings, substring):
return next(i for i, string in enumerate(strings) if substring in string)
If you are pre 2.6 you'll need to put the next()
at the end
如果您是2.6之前,则需要将next()放在最后
def first_substring(strings, substring):
return (i for i, string in enumerate(strings) if substring in string).next()
#4
2
def find(l, s):
for i in range(len(l)):
if l[i].find(s)!=-1:
return i
return None # Or -1
#5
2
This is quite slick and fairly efficient.
这很光滑,效率很高。
>>> def find(lst, predicate):
... return (i for i, j in enumerate(lst) if predicate(j)).next()
...
>>> l = ['the cat ate the mouse','the tiger ate the chicken','the horse ate the straw']
>>> find(l, lambda x: 'tiger' in x)
1
Only problem is that it will raise StopIteration if the item is not found (though that is easily remedied).
唯一的问题是,如果找不到该项,它将引发StopIteration(虽然这很容易解决)。
#6
1
def first_substring(strings, substring):
return min(i for i, string in enumerate(strings) if substring in string)
Note: This will raise ValueError
in case no match is found, which is better in my opinion.
注意:如果没有找到匹配,这将引发ValueError,这在我看来更好。
#7
1
>>> li = ['my','array','with','words']
>>> reduce(lambda tup, word: (tup[0], True) if not tup[1] and word == 'my' else (tup[0]+1 if not tup[1] else tup[0], tup[1]), li, (0, False))[0]
0
>>> reduce(lambda tup, word: (tup[0], True) if not tup[1] and word == 'words' else (tup[0]+1 if not tup[1] else tup[0], tup[1]), li, (0, False))[0]
3
#8
1
imho with this line, you'll find only the first occurence without processing the whole list
imho用这一行,你会发现只有第一次出现而没有处理整个列表
index = next((i for i in enumerate(l) if "tiger" in i[1]),[-1,-1])[0]
index = next((i代表i枚举(l)如果i [1]中的“tiger”,[ - 1,-1])[0]
#1
27
A non-slicky method:
一种非流畅的方法:
def index_containing_substring(the_list, substring):
for i, s in enumerate(the_list):
if substring in s:
return i
return -1
#2
4
With a one-liner:
使用单线程:
index = [idx for idx, s in enumerate(l) if 'tiger' in s][0]
#3
3
Variation of abyx solution (optimised to stop when the match is found)
abyx解决方案的变化(优化为在找到匹配时停止)
def first_substring(strings, substring):
return next(i for i, string in enumerate(strings) if substring in string)
If you are pre 2.6 you'll need to put the next()
at the end
如果您是2.6之前,则需要将next()放在最后
def first_substring(strings, substring):
return (i for i, string in enumerate(strings) if substring in string).next()
#4
2
def find(l, s):
for i in range(len(l)):
if l[i].find(s)!=-1:
return i
return None # Or -1
#5
2
This is quite slick and fairly efficient.
这很光滑,效率很高。
>>> def find(lst, predicate):
... return (i for i, j in enumerate(lst) if predicate(j)).next()
...
>>> l = ['the cat ate the mouse','the tiger ate the chicken','the horse ate the straw']
>>> find(l, lambda x: 'tiger' in x)
1
Only problem is that it will raise StopIteration if the item is not found (though that is easily remedied).
唯一的问题是,如果找不到该项,它将引发StopIteration(虽然这很容易解决)。
#6
1
def first_substring(strings, substring):
return min(i for i, string in enumerate(strings) if substring in string)
Note: This will raise ValueError
in case no match is found, which is better in my opinion.
注意:如果没有找到匹配,这将引发ValueError,这在我看来更好。
#7
1
>>> li = ['my','array','with','words']
>>> reduce(lambda tup, word: (tup[0], True) if not tup[1] and word == 'my' else (tup[0]+1 if not tup[1] else tup[0], tup[1]), li, (0, False))[0]
0
>>> reduce(lambda tup, word: (tup[0], True) if not tup[1] and word == 'words' else (tup[0]+1 if not tup[1] else tup[0], tup[1]), li, (0, False))[0]
3
#8
1
imho with this line, you'll find only the first occurence without processing the whole list
imho用这一行,你会发现只有第一次出现而没有处理整个列表
index = next((i for i in enumerate(l) if "tiger" in i[1]),[-1,-1])[0]
index = next((i代表i枚举(l)如果i [1]中的“tiger”,[ - 1,-1])[0]