在python中按日期和字符串排序 [英] Sort by date and string in python

问题描述

我有一堆文件名为

companyname-date_somenumber.txt

companyname-date_somenumber.txt

我必须根据公司名称对文件进行排序，然后根据日期对文件进行排序，然后按此排序顺序将其内容复制到另一个文本文件中.

I have to sort the files according to company name, then according to date, and copy their content in this sorted order to another text file.

这是我正在尝试的方法:

Here's the approach I'm trying :

从每个文件名中提取公司名称，然后提取日期，将这两个字段放入字典中，将此字典追加到列表中，然后根据公司名称的两个列对日期进行排序.

From each file-name, extract company name and then date, put these two fields in a dictionary, append this dictionary to a list and then sort this list according to the two columns of companyname and then date.

然后，一旦我获得了排序顺序，我想我可以根据刚刚获得的文件顺序在文件夹中搜索文件，然后将每个文件的内容复制到txt文件中，然后得到最终的txt文件

Then once I have the sorted order, I think I could search for the files in the folder according to the file-order I just obtained, then copy each files content into a txt file and I'll have my final txt file.

这是我到目前为止的代码:

Here's the code I have so far :

myfiles = [ f for f in listdir(path) if isfile(join(path,f)) ]
file_list=[]

for file1 in myfiles:

    # find indices of companyname and date in the file-name
    idx1=file1.index('-',0)
    idx2=file1.index('_',idx1)
    company=file1[0:idx1]  # extract companyname
    thisdate=file1[idx1+1:idx2]  #extract date, which is in format MMDDYY
    dict={}
    # extract month, date and year from thisdate 
    m=thisdate[0:2]
    d=thisdate[2:4]
    y='20'+thisdate[4:6]
    # convert into date object
    mydate = date(int(y), int(m), int(d))
    dict['date']=mydate
    dict['company']=company
    file_list.append(dict)  

我在此代码块的末尾检查了file_list的输出，我认为我有字典列表.现在，如何按公司名称和日期排序?我在网上查找了按多个键排序的信息，但是如何按日期获得递增的顺序?

I checked the output of file_list at the end of this block of code and I think I have my list of dicts. Now, how do I sort by companyname and then by date? I looked up sorting by multiple keys online but how would I get the increasing order by date?

还有其他方法可以按字符串对列表进行排序，然后对日期字段进行排序吗?

Is there any other way that I could sort a list by a string and then a date field?

推荐答案

import os
from datetime import datetime

MY_DIR = 'somedirectory'

# my_files = [ f for f in os.listdir(MY_DIR) if os.path.isfile(os.path.join(MY_DIR,f)) ]
my_files = [
    'ABC-031814_01.txt',
    'ABC-031214_02.txt',
    'DEF-010114_03.txt'
]
file_list = []

for file_name in my_files:
    company,_,rhs = file_name.partition('-')
    datestr,_,rhs = rhs.partition('_')
    file_date = datetime.strptime(datestr,'%m%d%y')
    file_list.append(dict(file_date=file_date,file_name=file_name,company=company))

for row in sorted(file_list,key=lambda x: (x.get('company'),x.get('file_date'))):
    print row

函数sorted带有关键字参数key，该参数是应用于要排序的序列中每个项目的函数.如果此函数返回一个元组，则该序列将按元组中的项目依次排序.

The function sorted takes a keyword argument key that is a function applied to each item in the sequence you're sorting. If this function returns a tuple, the sequence will be sorted by the items in the tuple in turn.

此处lambda x: (x.get('company'),x.get('file_date'))允许sorted按公司名称排序，然后按日期排序.

Here lambda x: (x.get('company'),x.get('file_date')) allows sorted to sort by company name and then by date.

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