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如何在R中一起使用变量值和正则表达式位置表达式?例如,在下面的代码中,我将如何替换仅出现在字符串开头或结尾的“zzz”的情况?这适用于“zzz”的所有值在R中使用正则表达式中的变量值
target_nos <- c("1","2","zzz","4")
sample_text <- cbind("1 dog 1","3 cats zzz","zzz foo 1")
for (i in 1:length(target_nos))
{
sample_text <- gsub(pattern = target_nos[i],replacement = "REPLACED", x =
sample_text)
}
但是,如何包含^和$位置标记?这将引发错误
sample_text <- gsub(pattern = ^target_nos[1],replacement = "REPLACED", x =
sample_text)
这将运行,但是从字面上解释变量,而不是调用值
sample_text <- gsub(pattern = "^target_nos[1]", replacement = "REPLACED", x =
sample_text)