python - 如何将python列表上的每月和每日文件名分成两个单独的列表？答案

【问题标题】：How to separate monthly and daily filenames on python list into two separate lists?python - 如何将python列表上的每月和每日文件名分成两个单独的列表？
【发布时间】：2020-09-08 12:01:14
【问题描述】：

我有一个清单：

allFiles =['https://myurl.com/something//something_01-01-2020.csv',
           'https://myurl.com/something//something_01-02-2020.csv', 
           'https://myurl.com/something//something_03-2020.csv'
           'https://myurl.com/something//something_01-03-2020.csv',
           'https://myurl.com/something//something_04-2020.csv'...]

如何将每月和每日文件分成两个单独的列表？

期望的输出：

   daily = ['https://myurl.com/something//something_01-01-2020.csv',
           'https://myurl.com/something//something_01-02-2020.csv', 
           'https://myurl.com/something//something_01-03-2020.csv']

   monthly = ['https://myurl.com/something//something_03-2020.csv',
              'https://myurl.com/something//something_04-2020.csv']

我尝试了以下方法但没有成功：

 daily = [ x for x in allFiles if "%m-%Y.csv" not in x ]

有人可以帮忙吗？提前谢谢！

【问题讨论】：

标签： python list

【解决方案1】：

这是一个使用regex 来识别每日和每月日期模式的解决方案，

import re

daily_pattern = re.compile(r"\d{2}-\d{2}-\d{4}.csv")
monthly_pattern = re.compile(r"\d{2}-\d{4}.csv")

monthly, daily = [], []

for f in allFiles:
    if daily_pattern.search(f):
        daily.append(f)
    elif monthly_pattern.search(f):
        monthly.append(f)
    else:
        print('invalid pattern %s' % f)

【讨论】：

【解决方案2】：

你可以拆分url只得到你想要的部分，然后计算连字符来查看日期的格式：

monthly = []
daily = []
for url in all_files:
  # splits the url string by '/', returns only the part after the last '/'
  filename = url.rsplit('/', 1)[-1]
  # same as before but split by '_' and getting only similar to 01-01-2020.csv
  
  datestring = filename.rsplit('_', 1)[-1]
  datestring_hyphens = datestring.count('-')

  if datestring_hyphens == 1:
    monthly.append(datestring)
  elif date_string_hyphens == 2:
    daily.append(datestring)

【讨论】：

【解决方案3】：

首先创建一个函数，允许对 URL 进行排序，以便对天和月进行分类

 allFiles =['https://myurl.com/something//something_01-01-2020.csv',
       'https://myurl.com/something//something_01-02-2020.csv', 
       'https://myurl.com/something//something_03-2020.csv'
       'https://myurl.com/something//something_01-03-2020.csv',
       'https://myurl.com/something//something_04-2020.csv']

def month_or_day(string):
    return len(string.split('_')[1].split(".")[0].split('-'))

然后创建一个数据框来将此函数应用于每个 URL

df=pd.DataFrame(allFiles,columns=['URL'])
df['Month_day']=0
df['intermediate'] =  pd.Series(allFiles).apply(lambda x : month_or_day(x))

你得到的URLS分隔如下：

print('Month : ',df[df['intermediate']==2]['URL'].tolist())
print('')
print('Day : ',df[df['intermediate']==3]['URL'].tolist())

【讨论】：

【解决方案4】：

你可以在这里使用正则表达式

例如：

import re

allFiles =['https://myurl.com/something//something_01-01-2020.csv',
           'https://myurl.com/something//something_01-02-2020.csv', 
           'https://myurl.com/something//something_03-2020.csv',
           'https://myurl.com/something//something_01-03-2020.csv',
           'https://myurl.com/something//something_04-2020.csv']

daily = []
monthly = []

for i in allFiles:
    if re.search(r"_(\d+\-\d+\.csv)$", i):
        monthly.append(i)
    else:
        daily.append(i)

print(daily)
print(monthly)

输出：

['https://myurl.com/something//something_01-01-2020.csv', 'https://myurl.com/something//something_01-02-2020.csv', 'https://myurl.com/something//something_01-03-2020.csv']

['https://myurl.com/something//something_03-2020.csv', 'https://myurl.com/something//something_04-2020.csv']

【讨论】：

【解决方案5】：

假设文件名中没有其他“_”：

monthly = [file for file in allFiles if len(file.split('_')[1].split('-')) == 2]
daily = [file for file in allFiles if len(file.split('_')[1].split('-')) == 3]

【讨论】：

【解决方案6】：

使用正则表达式：

import re

daily_pattern = r"""
    ^       # Start of string
    .+?     # Match anything except newline (not greedy)
    \d{2}   # Two numerical values.
    -       # Hyphen
    \d{2}   # Two numerical values.
    -       # Hyphen
    \d{4}   # Four numerical values.
    \.\w+   # File extension with escaped period.
    $       # End of string
"""

# Compile with re.M (ignore case) and re.X (handle pattern verbosity)
p = re.compile(daily_pattern, flags=re.I | re.X)

daily = [f for f in allFiles if p.match(f)]
monthly = [f for f in allFiles if not f in daily]

编辑：更新以包含更多解释。

【讨论】：

【解决方案7】：

可能是这样的

month_files = [f for f in allFiles if len(f.rpartition('_')[2].split('-'))==2]

day_files = [f for f in allFiles if len(f.rpartition('_')[2].split('-'))==3]

rpartition 将在 _ 上拆分文件并为您提供 3 个项目，例如 ['somename','_','the date/month .csv'] 您可以通过拆分和长度检查过滤日期部分。

使用rpartition，即使文件名有多个_，它也可以工作。

【讨论】：

【解决方案8】：

请注意，您的示例中有一个错误，缺少逗号。
您的问题非常适合正则表达式。

import re

allFiles =['https://myurl.com/something//something_01-01-2020.csv',
           'https://myurl.com/something//something_01-02-2020.csv', 
           'https://myurl.com/something//something_03-2020.csv',
           'https://myurl.com/something//something_01-03-2020.csv',
           'https://myurl.com/something//something_04-2020.csv']

dailyRegexp = re.compile(r".*\d\d-\d\d-\d\d\d\d\.csv$")
isDaily = lambda fn: dailyRegexp.match(fn)

daily = [fn for fn in allFiles if isDaily(fn)]
monthly = [fn for fn in allFiles if not isDaily(fn)]

print("Daily:", daily)
print("Monthly:", monthly)

正则表达式的解释：

.* 是任意字符 (.)，重复任意次 (*)
\d 是任意数字
- 只是文字字符-，没有特殊含义
\. 是一个点字符（用反斜杠转义以防止特殊含义）
csv 为字符串，无特殊含义
$ 是字符串的结尾

还要注意字符串前面的r。它表示防止 Python 将 \ 解释为特殊字符的原始字符串。更多信息：

正则表达式：https://docs.python.org/3/library/re.html
原始字符串：https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals

【讨论】：