regex - 非贪婪 gsub

Question

我有一个日志数据集:

V1  duration  id  startpoint
T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512  7771    1   2012-05-07_12-29-51
T<=>195[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501[=]N<=>360安全卫士[=]C<=>360.cn 7771    1   2012-05-07_12-29-51
T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501    7771    1   2012-05-07_12-29-51
T<=>211[=]P<=>360chrome.exe[=]I<=>436[=]U<=>www.hao123.com[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804  7771    1   2012-05-07_12-29-51 211

我正在尝试从第一列(时间点、进程、pid、url 等)中提取信息。起初我试过:

df$timepoint <- gsub("T<=>(.*)[=].*", "\\1", df$V1)

它返回类似 161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V< ，然后我尝试:

df$timepoint <- gsub("T<=>([0-9]*).*", "\\1", df$V1)

它有效，但在处理诸如进程名称之类的文本时不起作用，所以我搜索了“正则表达式最小匹配”并找到了术语 non-greedy .我又试了一次:

df$timepoint <- gsub("T<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$process <- gsub(".*P<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$pid <- gsub(".*I<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$url <- gsub(".*U<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$addr <- gsub(".*A<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$tab <- gsub(".*B<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$ver <- gsub(".*V<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$window <- gsub(".*W<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$name <- gsub(".*N<=>(.*?)\\[=\\].*", "\\1", df$V1)
df$company <- gsub(".*C<=>(.*?)", "\\1", df$V1)

并非每一行都包含所有信息并且发生了问题。如果没有关于软件名称或公司名称的信息，R 只需将 V1 复制到新的 var 中。如果软件版本信息在 V1 的末尾，则正则表达式 ".*V<=>(.*?)\\[=\\].*"还将整个字符串复制到新的var:

V1  duration  id  startpoint  timepoint process pid url addr  tab ver window  name  company
T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512  7771    1   2012-05-07_12-29-51 161 explorer.exe    1820    T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512  T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512  T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512  T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512  20094   T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512  T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512
T<=>195[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501[=]N<=>360安全卫士[=]C<=>360.cn 7771    1   2012-05-07_12-29-51 195 360Safe.exe 1732    T<=>195[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501[=]N<=>360安全卫士[=]C<=>360.cn T<=>195[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501[=]N<=>360安全卫士[=]C<=>360.cn T<=>195[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501[=]N<=>360安全卫士[=]C<=>360.cn 7, 5, 0, 1501   1017e   360安全卫士 360.cn
T<=>203[=]P<=>360chrome.exe[=]I<=>436[=]U<=>NULL[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804[=]N<=>360极速浏览器[=]C<=>360.cn    7771    1   2012-05-07_12-29-51 203 360chrome.exe   436 NULL    2027a   20290   5.2.0.804   T<=>203[=]P<=>360chrome.exe[=]I<=>436[=]U<=>NULL[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804[=]N<=>360极速浏览器[=]C<=>360.cn    360极速浏览器    360.cn
T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501    7771    1   2012-05-07_12-29-51 209 360Safe.exe 1732    T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501    T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501    T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501    T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501    1017e   T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501    T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501
T<=>211[=]P<=>360chrome.exe[=]I<=>436[=]U<=>www.hao123.com[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804  7771    1   2012-05-07_12-29-51 211 360chrome.exe   436 www.hao123.com  2027a   20290   T<=>211[=]P<=>360chrome.exe[=]I<=>436[=]U<=>www.hao123.com[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804  T<=>211[=]P<=>360chrome.exe[=]I<=>436[=]U<=>www.hao123.com[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804  T<=>211[=]P<=>360chrome.exe[=]I<=>436[=]U<=>www.hao123.com[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804  T<=>211[=]P<=>360chrome.exe[=]I<=>436[=]U<=>www.hao123.com[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804

我认为如果 R 找不到 'C<=>' (例如)，那么之后就没有 (.*?) 了。这将是一个空字符串，但输出占用了整个字符串。任何人都可以帮我解决它吗？谢谢!

更新

感谢 MrFlick 的评论，我刚刚得到了一个基于 this answer 的解决方案:

以提取软件名称信息的过程为例，

ind1 <- grep(".*N<=>(.*?)\\[=\\].*", df$V1, value= FALSE) # see if pattern exists with follow-up
ind2 <- grep(".*N<=>(.*?)", df$V1, value= FALSE) # see if pattern exists
df$name <- "" 
df$name[ind2] <- gsub(".*N<=>(.*?)", "\\1", df$V1) # replace the ones with pattern match
df$name[ind1] <- gsub(".*N<=>(.*?)\\[=\\].*", "\\1", df$V1) # replace the ones with pattern match and follow-up

但是这个片段看起来很糟糕，如果它是最终的解决方案，我必须通过其他信息(进程、pid、版本、公司等)来完成它......有人可以帮助优化它吗？谢谢!

Answer 1

这是另一种策略。我们可以使用gregexpr分离堆叠数据的每一个片段。这是向量中的数据

V1<-c("T<=>161[=]P<=>explorer.exe[=]I<=>1820[=]W<=>20094[=]V<=>6.00.2900.5512", 
"T<=>195[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501[=]N<=>360安全卫士[=]C<=>360.cn", 
"T<=>209[=]P<=>360Safe.exe[=]I<=>1732[=]W<=>1017e[=]V<=>7, 5, 0, 1501", 
"T<=>211[=]P<=>360chrome.exe[=]I<=>436[=]U<=>www.hao123.com[=]A<=>2027a[=]B<=>20290[=]V<=>5.2.0.804")

现在我们可以用

m <- gregexpr("(\\w)<=>(.*?)(?:\\[=\\]|$)", V1, perl=T)

找出匹配的匹配项可能会很麻烦，但我使用函数 regcapturedmatches轻松获取所有匹配的数据。我使用它就像你使用内置的 regmatches

data <- regcapturedmatches(V1,m)

那么如果你检查 data你可以看到所有的信息都在那里。现在的问题是我们只需要将它构建为列而不是像现在这样的行。为此，我使用 reshape2

library(reshape2)

#combine list into one data.frame
sdata<-do.call(rbind, lapply(1:length(data), 
    function(i) data.frame(data[[i]], S=i)))    

#turn rows into columns
dcast(sdata, S~X1, value.var="X2")

这又回来了

  S    I             P   T              V     W      C           N     A     B
1 1 1820  explorer.exe 161 6.00.2900.5512 20094   <NA>        <NA>  <NA>  <NA>
2 2 1732   360Safe.exe 195  7, 5, 0, 1501 1017e 360.cn 360安全卫士  <NA>  <NA>
3 3 1732   360Safe.exe 209  7, 5, 0, 1501 1017e   <NA>        <NA>  <NA>  <NA>
4 4  436 360chrome.exe 211      5.2.0.804  <NA>   <NA>        <NA> 2027a 20290
               U
1           <NA>
2           <NA>
3           <NA>
4 www.hao123.com

您可以重命名列等，但一次执行所有转换实际上并不是那么多代码。