每n個字分割一個字符向量

Question

如何將單個字符向量的單詞分割成列表中的每個向量包含一定數量的單詞的向量列表？

例如：

# reproducible data 
examp <- "Before asking a technical question by e-mail, or in a newsgroup, or on a website chat board, do the following: Try to find an answer by searching the archives of the forum you plan to post to. Try to find an answer by searching the Web. Try to find an answer by reading the manual. Try to find an answer by reading a FAQ. Try to find an answer by inspection or experimentation. Try to find an answer by asking a skilled friend. If you're a programmer, try to find an answer by reading the source code. When you ask your question, display the fact that you have done these things first; this will help establish that you're not being a lazy sponge and wasting people's time. Better yet, display what you have learned from doing these things. We like answering questions for people who have demonstrated they can learn from the answers. Use tactics like doing a Google search on the text of whatever error message you get (searching Google groups as well as Web pages). This might well take you straight to fix documentation or a mailing list thread answering your question. Even if it doesn't, saying 「I googled on the following phrase but didn't get anything that looked promising」 is a good thing to do in e-mail or news postings requesting help, if only because it records what searches won't help. It will also help to direct other people with similar problems to your thread by linking the search terms to what will hopefully be your problem and resolution thread. Take your time. Do not expect to be able to solve a complicated problem with a few seconds of Googling. Read and understand the FAQs, sit back, relax and give the problem some thought before approaching experts. Trust us, they will be able to tell from your questions how much reading and thinking you did, and will be more willing to help if you come prepared. Don't instantly fire your whole arsenal of questions just because your first search turned up no answers (or too many). Prepare your question. Think it through. Hasty-sounding questions get hasty answers, or none at all. The more you do to demonstrate that having put thought and effort into solving your problem before seeking help, the more likely you are to actually get help. Beware of asking the wrong question. If you ask one that is based on faulty assumptions, J. Random Hacker is quite likely to reply with a uselessly literal answer while thinking Stupid question..., and hoping the experience of getting what you asked for rather than what you needed will teach you a lesson." 

目前我做這個（基於https://stackoverflow.com/a/3318390/1036500）：

xx <- unlist(strsplit(examp, " ")) 
xxdf <- data.frame(examp = xx) 
n <- 50 # split every how many words? 
exampsplit <- split(xxdf, factor(sort(rank(row.names(xxdf))%%round(length(unlist(strsplit(examp, " ")))/n,0)))) 

這大約是我現在的目的不夠好，但我懷疑它可以提高對。什麼是更高效和準確的方法？

Answer 1

你可以試試下面

x <- unlist(strsplit(examp, "\\s+")) 
y <- split(x, seq_along(x)%/%50) 

y 
## $`0` 
## [1] "Before"  "asking"  "a"   "technical" "question" 
## [6] "by"   "e-mail," "or"   "in"   "a"   
## [11] "newsgroup," "or"   "on"   "a"   "website" 
## [16] "chat"  "board,"  "do"   "the"  "following:" 
## [21] ""   "Try"  "to"   "find"  "an"   
## [26] "answer"  "by"   "searching" "the"  "archives" 
## [31] "of"   "the"  "forum"  "you"  "plan"  
## [36] "to"   "post"  "to."  "Try"  "to"   
## [41] "find"  "an"   "answer"  "by"   "searching" 
## [46] "the"  "Web."  "Try"  "to"   
## 
## $`1` 
## [1] "find"    "an"    "answer"   "by"    
## [5] "reading"   "the"    "manual."   "Try"    
## [9] "to"    "find"    "an"    "answer"   
## [13] "by"    "reading"   "a"    "FAQ."    
## [17] "Try"    "to"    "find"    "an"    
## [21] "answer"   "by"    "inspection"  "or"    
## [25] "experimentation." "Try"    "to"    "find"    
## [29] "an"    "answer"   "by"    "asking"   
## [33] "a"    "skilled"   "friend."   "If"    
## [37] "you're"   "a"    "programmer,"  "try"    
## [41] "to"    "find"    "an"    "answer"   
## [45] "by"    "reading"   "the"    "source"   
## [49] "code."   "When"    
## 
## $`2` 
## [1] "you"   "ask"   "your"   "question," "display"  
## [6] "the"   "fact"   "that"   "you"   "have"   
## [11] "done"   "these"  "things"  "first;"  "this"   
## [16] "will"   "help"   "establish" "that"   "you're"  
## [21] "not"   "being"  "a"   "lazy"   "sponge"  
## [26] "and"   "wasting"  "people's"  "time."  "Better"  
## [31] "yet,"   "display"  "what"   "you"   "have"   
## [36] "learned"  "from"   "doing"  "these"  "things."  
## [41] "We"   "like"   "answering" "questions" "for"   
## [46] "people"  "who"   "have"   "demonstrated" "they"   
## 
## $`3` 
## [1] "can"   "learn"   "from"   "the"   
## [5] "answers."  "Use"   "tactics"  "like"   
## [9] "doing"   "a"    "Google"  "search"  
## [13] "on"   "the"   "text"   "of"   
## [17] "whatever"  "error"   "message"  "you"   
## [21] "get"   "(searching" "Google"  "groups"  
## [25] "as"   "well"   "as"   "Web"   
## [29] "pages)."  "This"   "might"   "well"   
## [33] "take"   "you"   "straight"  "to"   
## [37] "fix"   "documentation" "or"   "a"    
## [41] "mailing"  "list"   "thread"  "answering"  
## [45] "your"   "question."  "Even"   "if"   
## [49] "it"   "doesn't,"  
## 
## $`4` 
## [1] "saying"  "「I"   "googled" "on"   "the"  
## [6] "following" "phrase"  "but"  "didn't"  "get"  
## [11] "anything" "that"  "looked"  "promising」" "is"   
## [16] "a"   "good"  "thing"  "to"   "do"   
## [21] "in"   "e-mail"  "or"   "news"  "postings" 
## [26] "requesting" "help,"  "if"   "only"  "because" 
## [31] "it"   "records" "what"  "searches" "won't"  
## [36] "help."  "It"   "will"  "also"  "help"  
## [41] "to"   "direct"  "other"  "people"  "with"  
## [46] "similar" "problems" "to"   "your"  "thread"  
## 
## $`5` 
## [1] "by"   "linking"  "the"   "search"  "terms"  
## [6] "to"   "what"  "will"  "hopefully" "be"   
## [11] "your"  "problem"  "and"   "resolution" "thread."  
## [16] "Take"  "your"  "time."  "Do"   "not"   
## [21] "expect"  "to"   "be"   "able"  "to"   
## [26] "solve"  "a"   "complicated" "problem"  "with"  
## [31] "a"   "few"   "seconds"  "of"   "Googling." 
## [36] "Read"  "and"   "understand" "the"   "FAQs,"  
## [41] "sit"   "back,"  "relax"  "and"   "give"  
## [46] "the"   "problem"  "some"  "thought"  "before"  
## 
## $`6` 
## [1] "approaching" "experts." "Trust"  "us,"   "they"  
## [6] "will"  "be"   "able"  "to"   "tell"  
## [11] "from"  "your"  "questions" "how"   "much"  
## [16] "reading"  "and"   "thinking" "you"   "did,"  
## [21] "and"   "will"  "be"   "more"  "willing"  
## [26] "to"   "help"  "if"   "you"   "come"  
## [31] "prepared." "Don't"  "instantly" "fire"  "your"  
## [36] "whole"  "arsenal"  "of"   "questions" "just"  
## [41] "because"  "your"  "first"  "search"  "turned"  
## [46] "up"   "no"   "answers"  "(or"   "too"   
## 
## $`7` 
## [1] "many)."   "Prepare"  "your"   "question."  
## [5] "Think"   "it"    "through."  "Hasty-sounding" 
## [9] "questions"  "get"   "hasty"   "answers,"  
## [13] "or"    "none"   "at"    "all."   
## [17] "The"   "more"   "you"   "do"    
## [21] "to"    "demonstrate" "that"   "having"   
## [25] "put"   "thought"  "and"   "effort"   
## [29] "into"   "solving"  "your"   "problem"  
## [33] "before"   "seeking"  "help,"   "the"   
## [37] "more"   "likely"   "you"   "are"   
## [41] "to"    "actually"  "get"   "help."   
## [45] "Beware"   "of"    "asking"   "the"   
## [49] "wrong"   "question."  
## 
## $`8` 
## [1] "If"   "you"   "ask"   "one"   "that"   
## [6] "is"   "based"  "on"   "faulty"  "assumptions," 
## [11] "J."   "Random"  "Hacker"  "is"   "quite"  
## [16] "likely"  "to"   "reply"  "with"   "a"   
## [21] "uselessly" "literal"  "answer"  "while"  "thinking"  
## [26] "Stupid"  "question...," "and"   "hoping"  "the"   
## [31] "experience" "of"   "getting"  "what"   "you"   
## [36] "asked"  "for"   "rather"  "than"   "what"   
## [41] "you"   "needed"  "will"   "teach"  "you"   
## [46] "a"   "lesson."  
##