\ b不表现为与正则表达式/ Python的[复制]预期

Question

这个问题已经在这里有一个答案：

• Python regex - r prefix 4个回答

我试图用re.findall（）找到工作日名称的所有出现。当我排除\b，而不是当我包括他们它的工作原理。这工作：

any_week_day_long = "([Mm]onday|[Tt]uesday|[Ww]ednesday|[Tt]hursday|[Ff]riday|[Ss]aturday|[Ss]unday)"
match = re.findall(any_week_day_long, "Monday is a great day of the week. Tuesday is pretty good, but Wednesday has it beat.")

但这并不：

any_week_day_long = "\b([Mm]onday|[Tt]uesday|[Ww]ednesday|[Tt]hursday|[Ff]riday|[Ss]aturday|[Ss]unday)\b"
match = re.findall(any_week_day_long, "Monday is a great day of the week. Tuesday is pretty good, but Wednesday has it beat.")

在我看来，像它应该找到星期一，星期二和星期三刚刚与\b很好，但是当我print比赛，它只是一个空列表。

Answer 1

\b：而不是使用\\b尝试

any_week_day_long = "\\b([Mm]onday|[Tt]uesday|[Ww]ednesday|[Tt]hursday|[Ff]riday|[Ss]aturday|[Ss]unday)\\b"
match = re.findall(any_week_day_long, "Monday is a great day of the week. Tuesday is pretty good, but Wednesday has it beat.")

OUTPUT

['Monday', 'Tuesday', 'Wednesday']

Answer 2

你甚至可以达到使用raw string相同。而不是做类似[M|m]的，这是更好的使用re.IGNORECASE标志相同。一个更清洁的方式做同样的。

any_week_day_long = r'\b(?:mon|tues|wednes|thurs|fri|satur|sun)day\b'
match = re.findall(any_week_day_long, "Monday is a great day of the week. Tuesday is pretty good, but Wednesday has it beat.")  

输出：

['Monday', 'Tuesday', 'Wednesday']