regex - R从模式末尾提取子字符串直到第一次出现字符

Question

挣扎了几个小时才能得到这个匹配并在 R 中替换 gsub工作，仍然没有成功。
我正在尝试匹配模式 "Reason:"在一个字符串中，并在此模式之后提取所有内容，直到第一次出现点( . )
例如:

Offer Disposition. MSISDN: 7183067962. Offer: . Disposition: DECLINED. Reason: Not interested. ChannelID: CARE.

会返回 "Not interested"

Answer 1

这是一个解决方案:

s <- "Offer Disposition. MSISDN: 7183067962. Offer: . Disposition: DECLINED. Reason: Not interested. ChannelID: CARE."

sub(".*Reason: (.*?)\\..*", "\\1", s)
# [1] "Not interested"

更新(以解决评论):

如果您还有与模式不匹配的字符串，我建议使用 regexpr而不是 sub :

s2 <- c("no match example",
        "Offer Disposition. MSISDN: 7183067962. Offer: . Disposition: DECLINED. Reason: Not interested. ChannelID: CARE.")

match <- regexpr("(?<=Reason: ).*?(?=\\.)", s2, perl = TRUE)
ifelse(match == -1, NA, regmatches(s2, match))
# [1] NA                                "Not interested. ChannelID: CARE"

对于第二个示例，您可以使用以下正则表达式:

s3 <- "Delete Payment Arrangement of type Proof of Payment for BAN : 907295267 on date 02/01/2014, from reason PAERR."

# a)
sub(".*type (.*?) for.*", "\\1", s3)
# [1] "Proof of Payment"

# b)
match <- regexpr("(?<=type ).*?(?= for)", s3, perl = TRUE)
ifelse(match == -1, NA, regmatches(s3, match))
# [1] "Proof of Payment"