从R中的正则匹配创建数据帧

Question

我已经寻找了很多，但是不明白如何将正则匹配的输出转换为可以导出的任何内容。 希望这个问题不是那么具体，它对社区毫无价值。 我在以下链接中遇到了类似的问题：

使用R在几条推文中提取主题标签

但是，我无法从regmatches列表中找出如何保存/导出/制作数据框。 理想情况下，每个具有标签的标签都应保存在单独的列中。 但是只要我尝试我都会得到类似的输出：

[[6267]]
character(0)

[[6268]]
[1] "#ASCO15"

[[6269]]
[1] "#FDA"        "#Fast"       "#Track"      "#AML"        "#Pancreatic"    

如果我尝试导出regmatch的结果，则会得到：

Error in data.frame(character(0), character(0), character(0), character(0),  : 
  arguments imply differing number of rows: 0, 8, 2, 3, 5, 1, 4, 7, 6, 9 

谢谢

编辑：对不起，我可能在解释自己方面做得很差。

dput(hi)
structure(list(text = c("Hooray ! #Wimbledon2Day has plugged its brain back in at last ! No more sub- Top Gear telly #propertenniscoverage", 
"gone but never forgotten #TopGear ", "The final episode of 'Top Gear' with Jeremy Clarkson is going to break records http://brbr.co/1JCeJYc\312"
)), class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, 
-3L), .Names = "text")

从这些数据中，我想提取主题标签（＃）及其后的单词，并将其分配给列。 上面链接中的代码完成了第一部分。

test<-regmatches(hi$text,gregexpr("#(\\d|\\w)+",hi$text),)

给我：

[[1]]
[1] "#Wimbledon2Day"        "#propertenniscoverage"

[[2]]
[1] "#TopGear"

[[3]]
character(0)

但是当我尝试检查或导出它时，我得到：

Error in data.frame(c("#Wimbledon2Day", "#propertenniscoverage"), "#TopGear",  : 
  arguments imply differing number of rows: 2, 1, 0

Answer 1

如果您有大量推文和唯一的主题标签，则应考虑使用稀疏矩阵。 您可以在arules包中找到一个这样的稀疏矩阵对象itemMatrix 。 您可以将列表直接强制到此稀疏矩阵中，而不必在sapply的答案中写出unique且sapply步骤（这是一个很好的基本解决方案，我给他+1）。

foo <- c("RddzAlejandra: RT @NiallOfficial: What a day for @johnJoeNevin ! Sooo proud t have been there to see him at #London2012 and here in mgar #MullingarShuffle","BPOInsight: RT @atos: Atos completes delivery of key IT systems for London 2012 Olympic Games http://t.co/Modkyo2R #london2012","BloombergWest: The #Olympics sets a ratings record for #NBC, with 219M viewers tuning in. http://t.co/scGzIXBp #london2012 #tech")

ms <- regmatches(foo, gregexpr("#(\\d|\\w)+", foo))  # extract hashtags from tweet (from other post)

library(arules)
im <- as(ms, "itemMatrix")

#you can retrieve the rows like this
as(im,"matrix")
#   #london2012 #London2012 #MullingarShuffle #NBC #Olympics #tech
# 1           0           1                 1    0         0     0
# 2           1           0                 0    0         0     0
# 3           1           0                 0    1         1     1

Answer 2

使用链接文章中的示例，

foo <- c("RddzAlejandra: RT @NiallOfficial: What a day for @johnJoeNevin ! Sooo proud t have been there to see him at #London2012 and here in mgar #MullingarShuffle","BPOInsight: RT @atos: Atos completes delivery of key IT systems for London 2012 Olympic Games http://t.co/Modkyo2R #london2012","BloombergWest: The #Olympics sets a ratings record for #NBC, with 219M viewers tuning in. http://t.co/scGzIXBp #london2012 #tech")

ms <- regmatches(foo, gregexpr("#(\\d|\\w)+", foo))  # extract hashtags from tweet (from other post)
cols <- unique(unlist(ms))                           # get unique hashtags

setNames(data.frame(t(sapply(ms, function(i) cols %in% i))), cols)

#   #London2012 #MullingarShuffle #london2012 #Olympics  #NBC #tech
# 1        TRUE              TRUE       FALSE     FALSE FALSE FALSE
# 2       FALSE             FALSE        TRUE     FALSE FALSE FALSE
# 3       FALSE             FALSE        TRUE      TRUE  TRUE  TRUE

这些行对应于这些推文。