解析长字符串以检索 channel_id

Question

我从 Telegram 中提取了很多数据。但是，我无法隔离 channel_id。现在我有一个很长的字符串，在许多其他信息中包含 channel_id。问题是如何删除 channel_id 以外的所有内容，即“channel_id=XXXXXXXXXX)?

之后的数字

我的子集 data.frame

df <- structure(list(channel_id = c("MessageFwdHeader(date=datetime.datetime(2021, 5, 13, 20, 50, 47, tzinfo=datetime.timezone.utc), imported=False, from_id=PeerChannel(channel_id=1292436059), from_name=None, channel_post=1404, post_author=None, saved_from_peer=None, saved_from_msg_id=None, psa_type=None)", 
                                      "MessageFwdHeader(date=datetime.datetime(2021, 5, 4, 9, 24, 16, tzinfo=datetime.timezone.utc), imported=False, from_id=PeerChannel(channel_id=1480423705), from_name=None, channel_post=224, post_author=None, saved_from_peer=None, saved_from_msg_id=None, psa_type=None)", 
                                      "MessageFwdHeader(date=datetime.datetime(2021, 3, 25, 14, 9, 38, tzinfo=datetime.timezone.utc), imported=False, from_id=PeerChannel(channel_id=1489900933), from_name=None, channel_post=627, post_author=None, saved_from_peer=None, saved_from_msg_id=None, psa_type=None)", 
                                      "MessageFwdHeader(date=datetime.datetime(2021, 3, 12, 22, 10, 3, tzinfo=datetime.timezone.utc), imported=False, from_id=PeerChannel(channel_id=1455689590), from_name=None, channel_post=1457, post_author=None, saved_from_peer=None, saved_from_msg_id=None, psa_type=None)", 
                                      "MessageFwdHeader(date=datetime.datetime(2021, 3, 9, 12, 52, 5, tzinfo=datetime.timezone.utc), imported=False, from_id=PeerChannel(channel_id=1348575245), from_name=None, channel_post=None, post_author=None, saved_from_peer=None, saved_from_msg_id=None, psa_type=None)"
)), row.names = c(NA, -5L), class = c("data.table", "data.frame"))

想要的结果

channel_id <- structure(list(channel_id = c("1292436059", 
                                            "1480423705", 
                                            "1489900933", 
                                            "1455689590", 
                                            "1348575245"
)), row.names = c(NA, -5L), class = c("data.table", "data.frame"))

Answer 1

您可以尝试 regexpr 并使用 (?<=\(channel_id=) 向后看 (channel_id=，而不是匹配数字 \d+ 并向前看 )使用 (?=\)) 并使用 regmatches.

提取匹配项

regmatches(df$channel_id, regexpr("(?<=\(channel_id=)\d+(?=\))"
          , df$channel_id, perl=TRUE))
#[1] "1292436059" "1480423705" "1489900933" "1455689590" "1348575245"

或合并两个 sub.

sub(").*", "", sub(".*\(channel_id=", "", df$channel_id))
#[1] "1292436059" "1480423705" "1489900933" "1455689590" "1348575245

Answer 2

我们可以使用str_extract

library(stringr)
library(dplyr)
df %>%
    transmute(channel_id = str_extract(channel_id, "(?<=channel_id\=)\d+"))
   channel_id
1: 1292436059
2: 1480423705
3: 1489900933
4: 1455689590
5: 1348575245

解析长字符串以检索 channel_id

Parse long string to retrieve channel_id

string

parsing

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