我目前处理的字符串部分如下：
for (i,j) in huge_list_of_indices:
process(huge_text_block[i:j])
我想避免生成这些临时子串的开销.有任何想法吗？也许是以某种方式使用索引偏移的包装器？这是我目前的瓶颈.
请注意,process()是另一个期望字符串作为输入的python模块.
编辑：
有些人怀疑是否存在问题.以下是一些示例结果：
import time
import string
text = string.letters * 1000
def timeit(fn):
t1 = time.time()
for i in range(len(text)):
fn(i)
t2 = time.time()
print '%s took %0.3f ms' % (fn.func_name,(t2-t1) * 1000)
def test_1(i):
return text[i:]
def test_2(i):
return text[:]
def test_3(i):
return text
timeit(test_1)
timeit(test_2)
timeit(test_3)
输出：
test_1 took 972.046 ms test_2 took 47.620 ms test_3 took 43.457 ms
解决方法
我想你要找的是
buffers.
缓冲区的特征是它们“切片”支持缓冲区接口的对象而不复制其内容,但基本上在切片的对象内容上打开“窗口”.一些更多的技术解释可用于here.摘录：
Python objects implemented in C can export a group of functions called the “buffer interface.” These functions can be used by an object to expose its data in a raw,byte-oriented format. Clients of the object can use the buffer interface to access the object data directly,without needing to copy it first.
在您的情况下,代码应该看起来或多或少像这样：
>>> s = 'Hugely_long_string_not_to_be_copied' >>> ij = [(0,3),(6,9),(12,18)] >>> for i,j in ij: ... print buffer(s,i,j-i) # Should become process(...) Hug _lo string
HTH！