子集矢量列（根据情况）

Question

我想名字的矢量份额：

names <- c("DOE John", "VAN DYKE Dick", "SMITH Mary Jane") 

成两个向量

last <- c("DOE", "VAN DYKE", "SMITH") 

和

first <- c("John", "Dick", "Mary Jane") 

任何帮助将不胜感激。谢谢。

Answer 1

这应该工作：

# Define a pattern that only matches words composed entirely of capital letters 
pat <- paste("^[", paste(LETTERS, collapse=""), "]*$", sep="") 
# [1] "^[ABCDEFGHIJKLMNOPQRSTUVWXYZ]*$" 

names <- c("DOE John", "VAN DYKE Dick", "SMITH Mary Jane") 
splitNames <- strsplit(names, " ") 

# LAST NAMES: (Extract and paste together words matching 'pat') 
sapply(splitNames, 
     function(X) paste(grep(pat, X, value=TRUE), collapse=" ")) 
# [1] "DOE"  "VAN DYKE" "SMITH" 

# First Names: (Extract and paste together words NOT matching 'pat') 
sapply(splitNames, 
     function(X) paste(grep(pat, X, value=TRUE, invert=TRUE), collapse=" ")) 
# [1] "John"  "Dick"  "Mary Jane" 

匹配所有大写字母，你可以选择使用字符类[:upper:]，如：

pat <- "^[[:upper:]]*$" 

虽然在?regexp文档似乎轻度警告反对这样做，理由是便携性降低。

Answer 2

这里的一种方式：

l <- strsplit(names," ") 
splitCaps <- function(x){ 
    ind <- x == toupper(x) 
    list(upper = paste(x[ind],collapse = " "), 
     lower = paste(x[!ind],collapse = " ")) 
} 

> lapply(l,splitCaps) 
[[1]] 
[[1]]$upper 
[1] "DOE" 

[[1]]$lower 
[1] "John" 


[[2]] 
[[2]]$upper 
[1] "VAN DYKE" 

[[2]]$lower 
[1] "Dick" 


[[3]] 
[[3]]$upper 
[1] "SMITH" 

[[3]]$lower 
[1] "Mary Jane" 

做笔记，不过，这有大规模需要提醒的是，如果你开始不寻常的字符集混合挑选使用toupper的全部大写的话将是非常不可靠的，区域设置，符号等，但对于非常简单的ASCII类型的情况，它应该可以正常工作。