查找、重新格式化和替换字符串中的多个日期

Question

我有一个包含日期的长字符串，想更新所有日期的格式。

以下是我写的以及我无法弄清楚的伪代码：

import datetime

current_date_format = "%d/%m/%Y"
new_date_format = "%d/%b/%Y"

def main():
    line = "This is text dated 01/02/2017, and there are a few more dates such as 03/07/2017 and 09/06/2000"
    print(line)
    # Best way to pull out and replace all of the dates?
    # pseudo:
    for each current_date_format in line as date_in_line
        temp_date = fix_date(date_in_line)
        line.replace(date_in_line, temp_date)
    print(line)

def fix_date(date_string=''):
    return datetime.datetime.strptime(date_string, current_date_format).strftime(new_date_format)

在这种情况下如果应该打印：

This is text dated 01/02/2017, and there are a few more dates such as 03/07/2017 and 09/06/2000
This is text dated 01/FEB/2017, and there are a few more dates such as 03/JUL/2017 and 09/JUN/2000

谢谢

Answer 1

第一个建议不是一个完整的解决方案，请跳到下面的第一个编辑部分

如果您想通过几种方式调整您的代码，您可以这样做。首先将字符串分解成碎片：

line = "This is text dated 01/02/2017, and there are a few more dates such as 03/07/2017 and 09/06/2000"
words = line.split()  # by default it splits on whitespace

现在您可以使用您输入的每一个片段。然后，您可以尝试使用 fix_date 方法解析您的日期并重新构建字符串：

updated_line = ''
for word in words:
    try:
        updated_line += fix_date(word) + ' '
    except:
        updated_line += word + ' '
updated_line = updated_line[:-1] # gets rid of the extra trailing space
print(updated_line)

编辑：在运行时，我意识到日期上的标点符号存在问题。我正在做另一个传球。

这是一些工作代码：

import datetime
import re

current_date_format = "%d/%m/%Y"
new_date_format = "%d/%b/%Y"

def main():
    line = "This is text dated 01/02/2017, and there are a few more dates such as 03/07/2017 and 09/06/2000"
    print(line)
    line = re.sub(r'\d{2}/\d{2}/\d{4}',fix_date,line)
    print(line)

def fix_date(rem):
    date_string = rem.group()
    return datetime.datetime.strptime(date_string, current_date_format).strftime(new_date_format)

main()

编辑 2： 由于正则表达式方法适用于大字符串和小字符串，如果您的文件大小足够小，可以一次加载所有内容，您可以一次性完成：

import datetime
import re

current_date_format = "%d/%m/%Y"
new_date_format = "%d/%b/%Y"

def main():
    with open('my_file.txt','r') as f:
        text = f.read()
    with open('my_fixed_file.txt','w') as f:
        f.write(re.sub(r'\d{2}/\d{2}/\d{4}',fix_date,text))

def fix_date(rem):
    date_string = rem.group()
    return datetime.datetime.strptime(date_string, current_date_format).strftime(new_date_format)

main()

或者通过调整文件读/写部分来更紧凑：

...
with open('my_file.txt','r') as f:
    with open('my_fixed_file.txt','w') as f2:
        f2.write(re.sub(r'\d{2}/\d{2}/\d{4}',fix_date,f.read()))
...