如何使用正则表达式在python中进行复杂的替换？

Question

Here is the scenario:

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

What I want to do is to replace the str to "select * from records where year = 2003 and t1 = m1"

Could anyone tell me how to do it using python regex? Thanks!

Answer 1

If you use {..} instead of #{..} , you can use str.format_map or 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'

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Regular expression solution: Use re.sub with the replacement function as the second argument.

>>> 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'