如何用R中的readLines删除空行？

Question

如果文件中有很多空行，如何删除R中带有readLines的空行？

我知道我可以在read.table使用blank.lines.skip=T来删除它，在readLines怎么样？

另外，如何使用readLines删除最后一个\\n ？

Answer 1

如何使用选择运算符从readLines返回的字符向量中查找非空行？

# character vector mimicking readLine output, lines 2, 4, and 5 are blank
lines <- c("aaa", "", "ccc", "", "")
# [1] "aaa" ""    "ccc" ""    ""

# select lines which are blank
lines[which(lines=="")]
# [1] "" "" ""

# conversely, lines which are not
lines[which(lines!="")]
# [1] "aaa" "ccc"

我上面使用了假的readLine数据，但实际上我没有看到readLines为空行或最后一行返回\\n 。

Answer 2

一个可重复的例子：

  Z <- readLines(textConnection("line1 , stuff, other stuff\nline2 ,junk\nline3, a blank two lines follow\n\n\nline6\n"))
>     Z
[1] "line1 , stuff, other stuff"      "line2 ,junk"                     "line3, a blink two lines follow"
[4] ""                                ""                                "line6"                          
[7] ""                               
>     Z1 <- Z[sapply(Z, nchar) > 0] # the zero length lines get removed.
> Z1
[1] "line1 , stuff, other stuff"      "line2 ,junk"                     "line3, a blank two lines follow"
[4] "line6"          

@Andrie建议你这样做：

> Z <- scan(textConnection("line1 , stuff, other stuff\nline2 ,junk\nline3, a blink two lines follow\n\n\nline6\n"), 
            what="", sep="\n",blank.lines.skip=TRUE)
Read 4 items
>     Z
[1] "line1 , stuff, other stuff"      "line2 ,junk"                     "line3, a blink two lines follow"
[4] "line6"