如何使用正則表達式在python中進行復雜的替換？

Question

這是場景：

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

我想做的是將str替換為“從year = 2003和t1 = m1的記錄中選擇*”

誰能告訴我如何使用python正則表達式嗎？ 謝謝！

Answer 1

如果您使用{..}而不是#{..} ，則可以使用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'

---

正則表達式解決方案：將re.sub與替換函數一起用作第二個參數。

>>> 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'