string 如何将字符列表折叠为 R 中的单个字符串
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/9314328/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to collapse a list of characters into a single string in R
提问by userJT
There is a list which I would like to output into an excel file as a single string. I start with a list of characters.
有一个列表，我想将其作为单个字符串输出到 excel 文件中。我从一个字符列表开始。
url="http://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=pubmed&id=21558518&retmode=xml"
xml = xmlTreeParse(url,useInternal = T)
ns <- getNodeSet(xml, '//PublicationTypeList/PublicationType')
types <- sapply(ns, function(x) { xmlValue(x) } )
types
Output is this:
输出是这样的：
[1] "Journal Article" "Multicenter Study" "Research Support, N.I.H., Extramural"
[4] "Research Support, Non-U.S. Gov't"
So in types - there is a list of characters Now I need to make into a single string. This is what I have so far but it is not optimal:
所以在类型中 - 有一个字符列表现在我需要变成一个字符串。这是我到目前为止所拥有的，但不是最佳的：
types_as_string = as.character(types[[1]])
if (length(types) > 1) for (j in 2:length(types)) types_as_string = paste(types_as_string,"| ",as.character(types[[j]]),sep="")
types_as_string
[1] "Journal Article| Multicenter Study| Research Support, N.I.H., Extramural| Research Support, Non-U.S. Gov't"
So I want to end up with a nice string separated by pipes or other separator. (the last code part - is what I want to re-write nicely). The pipes are important and they have to be properly done.
所以我想得到一个由管道或其他分隔符分隔的漂亮字符串。（最后的代码部分 - 是我想很好地重写的部分）。管道很重要，必须正确完成。
回答by ilya
You can do it with pastefunction
你可以用paste函数来做
> paste(c('A', 'B', 'C'), collapse=', ' )
[1] "A, B, C"
回答by Chernoff
You can do it with str_cfunction
你可以用str_c函数来做
> library('stringr')
> str_c(c('A','B','C'),collapse=',')
[1] "A,B,C"
