R中一个非常基本的问题，但解决方案尚不清楚。
如何将字符向量拆分为其单个字符，即paste(..., sep='')or的反面stringr::str_c()？
任何比这更笨重的东西：
sapply(1:26, function(i) { substr("ABCDEFGHIJKLMNOPQRSTUVWXYZ",i,i) } )
"A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" "T" "U" "V" "W" "X" "Y" "Z"
是否可以以其他方式完成，例如使用strsplit()或stringr::*其他方式？
是的，strsplit会做的。 strsplit返回一个列表，因此您可以使用unlist将字符串强制转换为单个字符向量，或使用列表索引[[1]]来访问第一个元素。
x <- paste(LETTERS, collapse = "")
unlist(strsplit(x, split = ""))
# [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S"
#[20] "T" "U" "V" "W" "X" "Y" "Z"
或（注意实际上没有必要命名split参数）
strsplit(x, "")[[1]]
# [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S"
#[20] "T" "U" "V" "W" "X" "Y" "Z"
您也可以拆分NULL或拆分character(0)相同的结果。
str_extract_all()fromstringr提供了一种执行此操作的好方法：
str_extract_all("ABCDEFGHIJKLMNOPQRSTUVWXYZ", boundary("character"))
[[1]]
[1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" "T" "U"
[22] "V" "W" "X" "Y" "Z"
为了清楚起见，这是逐步呈现的；在实践中，将创建一个函数。
查找任何字符按顺序重复的次数
the_string <- "BaaaaaaH"
# split string into characters
the_runs <- strsplit(the_string, "")[[1]]
# find runs
result <- rle(the_runs)
# find values that are repeated
result$values[which(result$lengths > 1)]
#> [1] "a"
# retest with more runs
the_string <- "BaabbccH"
# split string into characters
the_runs <- strsplit(the_string, "")[[1]]
# find runs
result <- rle(the_runs)
# find values that are repeated
result$values[which(result$lengths > 1)]
#> [1] "a" "b" "c"