元组比Python中的列表更有效吗? [英] Are tuples more efficient than lists in Python?

问题描述

在元素的实例化和检索方面，元组和列表之间是否存在性能差异?

Is there any performance difference between tuples and lists when it comes to instantiation and retrieval of elements?

推荐答案

dis 模块反汇编函数的字节码，对于查看元组和列表之间的区别很有用.

The dis module disassembles the byte code for a function and is useful to see the difference between tuples and lists.

在这种情况下，您可以看到访问元素会生成相同的代码，但是分配元组要比分配列表快得多.

In this case, you can see that accessing an element generates identical code, but that assigning a tuple is much faster than assigning a list.

>>> def a():
...     x=[1,2,3,4,5]
...     y=x[2]
...
>>> def b():
...     x=(1,2,3,4,5)
...     y=x[2]
...
>>> import dis
>>> dis.dis(a)
  2           0 LOAD_CONST               1 (1)
              3 LOAD_CONST               2 (2)
              6 LOAD_CONST               3 (3)
              9 LOAD_CONST               4 (4)
             12 LOAD_CONST               5 (5)
             15 BUILD_LIST               5
             18 STORE_FAST               0 (x)

  3          21 LOAD_FAST                0 (x)
             24 LOAD_CONST               2 (2)
             27 BINARY_SUBSCR
             28 STORE_FAST               1 (y)
             31 LOAD_CONST               0 (None)
             34 RETURN_VALUE
>>> dis.dis(b)
  2           0 LOAD_CONST               6 ((1, 2, 3, 4, 5))
              3 STORE_FAST               0 (x)

  3           6 LOAD_FAST                0 (x)
              9 LOAD_CONST               2 (2)
             12 BINARY_SUBSCR
             13 STORE_FAST               1 (y)
             16 LOAD_CONST               0 (None)
             19 RETURN_VALUE

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