[英]Difference in time complexity between python .index() and .find()
[英]difference between find and index
我是 python 的新手,不能完全理解 find 和 index 之間的區別。
>>> line
'hi, this is ABC oh my god!!'
>>> line.find("o")
16
>>> line.index("o")
16
它們總是返回相同的結果。 謝謝!!
還 find 僅適用於字符串,而索引可用於列表、元組和字符串
>>> somelist
['Ok', "let's", 'try', 'this', 'out']
>>> type(somelist)
<class 'list'>
>>> somelist.index("try")
2
>>> somelist.find("try")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'list' object has no attribute 'find'
>>> sometuple
('Ok', "let's", 'try', 'this', 'out')
>>> type(sometuple)
<class 'tuple'>
>>> sometuple.index("try")
2
>>> sometuple.find("try")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'find'
>>> somelist2
"Ok let's try this"
>>> type(somelist2)
<class 'str'>
>>> somelist2.index("try")
9
>>> somelist2.find("try")
9
>>> somelist2.find("t")
5
>>> somelist2.index("t")
5
@falsetru 提供了關於函數之間差異的解釋,我在它們之間進行了性能測試。
"""Performance tests of 'find' and 'index' functions.
Results:
using_index t = 0.0259 sec
using_index t = 0.0290 sec
using_index t = 0.6851 sec
using_find t = 0.0301 sec
using_find t = 0.0282 sec
using_find t = 0.6875 sec
Summary:
Both (find and index) functions have the same performance.
"""
def using_index(text: str, find: str) -> str:
"""Returns index position if found otherwise raises ValueError."""
return text.index(find)
def using_find(text: str, find: str) -> str:
"""Returns index position if found otherwise -1."""
return text.find(find)
if __name__ == "__main__":
from timeit import timeit
texts = [
"short text to search" * 10,
"long text to search" * 10000,
"long_text_with_find_at_the_end" * 10000 + " to long",
]
for f in [using_index, using_find]:
for text in texts:
t = timeit(stmt="f(text, ' ')", number=10000, globals=globals())
print(f"{f.__name__} {t = :.4f} sec")
print()
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.