1.1 重构的重要性 重构,就如同对一幅日渐模糊的油画进行细致入微的修复和重新布局,它不是改变画的主题,而是使之更加鲜明生动。在编程领域,重构是指在不改变代码外部行为的前提下,对其内部结构进行改进的过程,旨在提升代码的可读性、可维护性和可扩展性。 1.1.1 何为重构 想象一下,你接手了一段复杂的Python代码,...
上图是官方网站 TimeComplexity - Python Wiki 给出的 list 各种操作的时间复杂度。可以看到,在末尾增删数据时,时间复杂度为常数;但一般的增删操作平均需要 O(n) 的复杂度;检查是否包含某个数据,也要 O(n) 的复杂度; 但修改某下标处的数据只需要常数的时间复杂度。 正如前面所说,红黑树的查找、插入、删除复...
def merge_sort(alist): """归并排序""" n = len(alist) if n <= 1: return alist mid = n // 2 # left 采用归并排序后形成的有序的新的列表 left_li = merge_sort(alist[:mid]) # right 采用归并排序后形成的有序的新的列表 right_li = merge_sort(alist[mid:]) # 将两个有序的子...
A function that merges both halves, producing a sorted array Here’s the code to merge two different arrays: Python 1def merge(left, right): 2 # If the first array is empty, then nothing needs 3 # to be merged, and you can return the second array as the result 4 if len(left) ...
...In Python, the sum and len functions are used to calculate the sum and length of a list, and the mean...In R, the print function is used to print values to the console...In Python, the print function is used in a similar way, but it also requires parentheses around the...
To perform set operations like s-t, both s and t need to be sets. However you can do the method equivalents even if t is any iterable, for example s.difference(l), where l is a list. dict The Average Case times listed for dict objects assume that the hash function for the objects...
from cmath import pi, exp def discrete_fourier_transform(x, k): omega = 2 * pi * k / (N := len(x)) return sum(x[n] * exp(-1j * omega * n) for n in range(N)) This function is a literal transcription of the formulas above. Now you can run a frequency analysis on a...
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if some_long_module.some_long_predicate_function( really_long_variable_name) else 'no, false, negative, nay') 1. 2. 3. 4. 5. 2.12 默认参数值 大多数情况下都OK 2.12.1 定义 在函数参数列表的最后可以为变量设定值,例如def foo(a, b=0):.如果foo在调用时只传入一个参数,那么b变量就被设定...
#compares the running time of a list compared to a generatorimporttime#generator function creates an iterator of odd numbers between n and mdefoddGen(n,m):whilen<m:yieldn n+=2#builds a list of odd numbers between n and mdefoddLst(n,m): ...