我想为R中的数字生成sequential citation numbers。如果数字是连续的,则应该用连字符分隔数字。否则,数字用逗号分隔。例如,号码1, 2, 3, 5, 6, 8, 9, 10, 11 and 13
应该出现为1-3,5,6,8-11,13
。R中的连续引用编号:连字符中的单独数字,如果顺序 - 如果不是,则添加逗号
这个问题已经被previously answered for c#了,我写了一个适用于R的函数,但是这个函数可以改进。我发布这个问题作为其他可能有类似需求的参考。如果您发现R(我没有)的类似问题,请投票结束,我将删除该问题。
下面的功能不是很优雅,但似乎做的工作。 如何使功能更短,更优雅?
x <- c(1,2,3,5,6,8,9,10,11,13)
library(zoo) ## the function requires zoo::na.approx function
##' @title Generate hyphenated sequential citation from an integer vector
##' @param x integer vector giving citation or page numbers
##' @importFrom zoo na.approx
seq.citation <- function(x) {
## Result if lenght of the integer vector is 1.
if(length(x) == 1) return(x) else {
## Sort
x <- sort(x)
## Difference
df <- diff(x)
## Index to determine start and end points
ind <- c("start", rep("no", length(df)-1), "end")
ind[which(df > 1)] <- "end"
## Temporary start point vector
sts <- which(ind == "end") + 1
ind[sts[sts < length(ind)]] <- "start"
## Replace the first index element
ind[1] <- "start"
## Replace the last index element, if preceding one is "end"
if(ind[length(ind)-1] == "end") ind[length(ind)] <- "start"
## Groups for comma separation using "start" as the determining value.
grp <- rep(NA, length(x))
grp[which(ind == "start")] <- 1:length(grp[which(ind == "start")])
grp <- zoo::na.approx(grp, method = "constant", rule = 2)
## Split sequences by group
seqs <- split(x, grp)
seqs <- lapply(seqs, function(k) {
if(length(k) == 1) k else {
if(length(k) == 2) paste(k[1], k[2], sep = ",") else {
paste(k[1], k[length(k)], sep = "-")
}}
})
## Result
return(do.call("paste", c(seqs, sep = ",")))
}
}
seq.citation(x)
# [1] "1-3,5,6,8-11,13"
还参见,类似的[交](https://stackoverflow.com/questions/34636461/function-to-summarize - 数字的向量 - 字符串) –