所有这些看起来非常相似的功能之间有什么区别？
答案 0 :(得分：7)
stri_join，stri_c和stri_paste来自程序包 stringi ，它们是纯别名
str_c来自 stringr ，只是stringi::stri_join，其参数ignore_null硬编码为TRUE，而{ {1}}的默认设置为stringi::stri_join。 FALSE是stringr::str_join
请参阅：
str_c library(stringi)
identical(stri_join, stri_c)
# [1] TRUE
identical(stri_join, stri_paste)
# [1] TRUE
library(stringr)
str_c
# function (..., sep = "", collapse = NULL)
# {
# stri_c(..., sep = sep, collapse = collapse, ignore_null = TRUE)
# }
# <environment: namespace:stringr>
与stri_join非常相似，下面列举了一些区别：
1。 base::paste默认情况下
因此，默认情况下，它的行为更像sep = ""，但是paste0失去了paste0参数。
sep identical(paste0("a","b") , stri_join("a","b"))
# [1] TRUE
identical(paste("a","b") , stri_join("a","b",sep=" "))
# [1] TRUE
identical(paste("a","b", sep="-"), stri_join("a","b", sep="-"))
# [1] TRUE
的行为与此处的str_c一样。
2。 stri_join
如果使用NA粘贴到NA，则结果为stri_join，而NA将paste转换为NA
"NA" paste0(c("a","b"),c("c",NA))
# [1] "ac" "bNA"
stri_join(c("a","b"),c("c",NA))
# [1] "ac" NA
的行为也将与str_c一样
3。具有长度stri_join个参数的行为
遇到长度为0的值时，将返回0，除非将character(0)设置为ignore_null，则将忽略该值。它与FALSE的行为不同，后者的行为是将长度paste的值转换为0，因此在输出中包含2个连续的分隔符。
"" 4。 stri_join("a",NULL, "b")
# [1] character(0)
stri_join("a",character(0), "b")
# [1] character(0)
paste0("a",NULL, "b")
# [1] "ab"
stri_join("a",NULL, "b", ignore_null = TRUE)
# [1] "ab"
str_c("a",NULL, "b")
# [1] "ab"
paste("a",NULL, "b") # produces double space!
# [1] "a b"
stri_join("a",NULL, "b", ignore_null = TRUE, sep = " ")
# [1] "a b"
str_c("a",NULL, "b", sep = " ")
# [1] "a b"
警告更多
stri_join 5。 paste(c("a","b"),c("c","d","e"))
# [1] "a c" "b d" "a e"
paste("a","b", sep = c(" ","-"))
# [1] "a b"
stri_join(c("a","b"),c("c","d","e"), sep = " ")
# [1] "a c" "b d" "a e"
# Warning message:
# In stri_join(c("a", "b"), c("c", "d", "e"), sep = " ") :
# longer object length is not a multiple of shorter object length
stri_join("a","b", sep = c(" ","-"))
# [1] "a b"
# Warning message:
# In stri_join("a", "b", sep = c(" ", "-")) :
# argument `sep` should be one character string; taking the first one
更快
stri_join