如何在多行中替换单个字线？

Posted 2023-02-25

【中文标题】如何在多行中替换单个字线？

【英文标题】：How to replace single word line in multiple lines?

【发布时间】：2018-07-03 06:49:05

【问题描述】：

我有一些字符串的数据框。有些行有一个单词，我想用空白替换。我可以检索单词，但在替换它们时我收到警告消息

警告信息：在 gsub(pattern = text[lengths(gregexpr("[[:alpha:]]+", text)) == : 参数 'pattern' 的长度 > 1 并且只使用第一个元素

只有第一个单词被替换，其余单词保持原样。我想替换数据框中的所有单个单词。

我使用的代码如下。

text <- c("Because I could not stop for Death -",
          "Word1",
          "He kindly stopped for me -",
          "Word2",
          "The Carriage held but just Ourselves - ",
          "word3",
          "and Immortality")

gsub(pattern = text[lengths(gregexpr("[[:alpha:]]+", text)) == 1], "", text)

我期待低于输出。

"Because I could not stop for Death -",
          "He kindly stopped for me -",
          "The Carriage held but just Ourselves - ",
          "and Immortality"

【问题讨论】：

你的预期输出是什么？

我添加了有问题的预期输出。

【参考方案1】：

在这里，一个简单的逻辑索引就可以解决问题，因为您要保留的单词似乎位于位置 1、3、5、... 等等，即

text[c(TRUE, FALSE)]
#[1] "Because I could not stop for Death -"    "He kindly stopped for me -"             
#[3] "The Carriage held but just Ourselves - " "and Immortality"

【参考方案2】：

a=gsub("^\\w+$","",text)
[1] "Because I could not stop for Death -"    ""                                       
[3] "He kindly stopped for me -"              ""                                       
[5] "The Carriage held but just Ourselves - " ""                                       
[7] "and Immortality"   

grep("\\w",a,value = T)
[1] "Because I could not stop for Death -"    "He kindly stopped for me -"             
[3] "The Carriage held but just Ourselves - " "and Immortality"  

或者你可以简单地做

grep("\\w+\\s",text,value = T)
[1] "Because I could not stop for Death -"    "He kindly stopped for me -"             
[3] "The Carriage held but just Ourselves - " "and Immortality"  

【参考方案3】：

您能否尝试关注一下，如果这对您有帮助，请告诉我。

text <- c("Because I could not stop for Death -",
          "Word1",
          "He kindly stopped for me -",
          "Word2",
          "The Carriage held but just Ourselves - ",
          "word3",
          "and Immortality")

获取 OP 所需输出的代码：

text[!grepl("[Ww]ord[0-9]+", text)] 

输出如下。

[1] "Because I could not stop for Death -"    "He kindly stopped for me -"             
[3] "The Carriage held but just Ourselves - " "and Immortality"

来自帮助页面的grepl：

grepl 返回一个逻辑向量（x 的每个元素是否匹配）。