在 R 中连接字符向量，其中某些元素具有 0 个字符

Question

我有字符向量，其中一些元素有 0 个字符。我想连接它们，但忽略了这 0 个元素：

x <- c("a", "b", "", "d", "", "f")
y <- c("a", "", "c", "", "e", "f")
z <- c("a", "", "c", "d", "", "f")

paste(x, y, z, sep = ":")
# This gives:
# [1] "a:a:a" "b::"   ":c:c"  "d::d"  ":e:"   "f:f:f"

# But I want this:

# "a:a:a" "b"   "c:c"  "d:d"  "e"   "f:f:f"

编辑：上面是一个简化的例子，这是一个更好的近似值（我将评论连接到单个字段）

x <- c("alpah beta", "better", "", "delta", "")
y <- c("alpha", "", "c", "", "fox, one")
z <- c("alpha", "", "can of worms", "delta", "")

paste(x, y, z, sep = "; ")
# Gives:
# "alpha beta; alpha; alpha" "better; ; " "; c; can of worms" "delta; ; delta" "; fox, one; "

# required
# "alpha beta; alpha; alpha"  "better"  "c; can of worms"  "delta; delta"  "fox, one"

我也对将“”替换为 NA 但给出相同结果的解决方案感兴趣。

Answer 1

您可以 paste0 将它们组合在一起，这样会忽略空格，然后 strsplit 每个字符和 paste 它们重新组合在一起，与 : 折叠。

sapply(strsplit(paste0(x,y,z),""),paste,collapse=":")
[1] "a:a:a" "b"     "c:c"   "d:d"   "e"     "f:f:f"

更新示例

另一种方法是使用 Reduce 和自定义函数来检查空白元素：

Reduce(function (x,y) ifelse(x==""|y=="",paste0(x,y),paste(x,y,sep=":")),list(x,y,z))
[1] "alpah beta:alpha:alpha" "better"                 "c:can of worms"        
[4] "delta:delta"            "fox, one"

Answer 2

这是一个使用 gsub

的选项

gsub("^:+|:+$|:(?=:)", "", paste(x, y, z, sep = ":"), perl = TRUE)
#[1] "a:a:a" "b"     "c:c"   "d:d"   "e"     "f:f:f"

更新

以上代码也适用于更新后的示例（由于 OP 更改了分隔符，我们也在更改它）

gsub("^; |; $|; (?=;)", "", paste(x, y, z, sep = "; "), perl = TRUE)
#[1] "alpah beta; alpha; alpha" "better"                  
#[3] "c; can of worms"          "delta; delta"            
#[5] "fox, one"

注意：OP 在 'x' 中的输入字符串是 alpah。

在 R 中连接字符向量，其中某些元素具有 0 个字符

Concatenate character vectors in R where some elements have 0 characters

string

r

concatenation

character

paste

更新