如何使用正则表达式在python中进行复杂的替换？

Question

以下是该方案：

dict = {'t1': 'm1', 'year': '2003'}
pattern = re.compile(r'#\{(.*?)\}')
str = "select * from records where year = #{year} and t1 = #{t1}"

我想要做的是将str替换为“select * from year = year and t1 = m1”

有人能告诉我如何使用python正则表达式吗？谢谢！

Answer 1

如果您使用{..}代替#{..}，则可以使用str.format_map或str.format：

>>> d = {'t1': 'm1', 'year': '2003'}
>>> fmt = "select * from records where year = {year} and t1 = {t1}"
>>> fmt.format_map(d) # available only in Python 3.2+
'select * from records where year = 2003 and t1 = m1'
>>> fmt.format(**d)
'select * from records where year = 2003 and t1 = m1'

---

正则表达式解决方案：使用re.sub替换函数作为第二个参数。

>>> d = {'t1': 'm1', 'year': '2003'}
>>> fmt = "select * from records where year = #{year} and t1 = #{t1}"
>>> import re
>>> re.sub(r'#\{(.*?)\}', lambda m: d[m.group(1)], fmt) # m -> match object
'select * from records where year = 2003 and t1 = m1'