python统计一个文本中重复行数的方法

　　本文实例讲述了python统计一个文本中重复行数的方法。分享给大家供大家参考。具体实现方法如下：

　　比如有下面一个文件
2
3
1
2
我们期望得到
2,2
3,1
1,1

　　解决问题的思路:

　　出现的文本作为key, 出现的数目作为value,然后按照value排除后输出
最好按照value从大到小输出出来,可以参照：
复制代码 代码如下:in recent Python 2.7, we have new OrderedDict type, which remembers the order in which the items were added.
>>> d = {third: 3, first: 1, fourth: 4, second: 2}
>>> for k, v in d.items():
... print %s: %s % (k, v)
...
second: 2
fourth: 4
third: 3
first: 1
>>> d
{second: 2, fourth: 4, third: 3, first: 1}To make a new ordered dictionary from the original, sorting by the values:
>>> from collections import OrderedDict
>>> d_sorted_by_value = OrderedDict(sorted(d.items(), key=lambda x: x[1]))The OrderedDict behaves like a normal dict:
>>> for k, v in d_sorted_by_value.items():
... print %s: %s % (k, v)
...
first: 1
second: 2
third: 3
fourth: 4
>>> d_sorted_by_value
OrderedDict([(first: 1), (second: 2), (third: 3), (fourth: 4)])
代码如下:
复制代码 代码如下:#coding=utf-8
import operator
f = open(f.txt)
count_dict = {}
for line in f.readlines():
line = line.strip()
count = count_dict.setdefault(line, 0)
count += 1
count_dict[line] = count
sorted_count_dict = sorted(count_dict.iteritems(), key=operator.itemgetter(1), reverse=True)
for item in sorted_count_dict:
print %s,%d % (item[0], item[1])

　　补充说明:
1. python的dict对象的两个方法:

　　items方法将所有的字典项以列表的方式返回, 这些列表项中每一项都来自于(键, 值)
iteritems方法与items的作用大致相同, 但是返回一个迭代器对象而不是列表

　　2. python的内建函数sorted
复制代码 代码如下:>>> help(sorted)
Help on built-in function sorted in module __builtin__:
sorted(...)
sorted(iterable, cmp=None, key=None, reverse=False) --> new sorted list

　　希望本文所述对大家的Python程序设计有所帮助。