从具有基于特定值的多个元素的向量中获取索引

Question

我有一个矢量：

lst <- c("2,1","7,10","11,0","7,0","10,0","1,1","1,0","4,0","4,1","0,1","6,0")

每个元素包含两个数字，用＆＃34;，＆＃34;分隔。我想得到包含＆＃34; 1＆＃34;的元素的索引。 所以索引列表是预期的：

1, 6, 7, 9, 10

Answer 1

grep()可以很好地解决这个问题。默认情况下，它返回匹配模式的索引。

grep("^1,|,1$", lst)
# [1]  1  6  7  9 10

正则表达式^1,|,1$看起来匹配

的字符串

• ^1, =以1,
开头
• |或
• ,1$ =以,1
结尾

Answer 2

每个元素包含两个数字。我的回答并不理想，但我得到了我需要的东西。

m <- as.numeric(unlist(lapply(strsplit(as.character(lst), "\\,"),"[[",1)))
n <- as.numeric(unlist(lapply(strsplit(as.character(lst), "\\,"),"[[",2)))
sort(unique(c(which(m==1),which(n==1))))

Answer 3

根据此任务的背景和上下文，将此向量转换为data.frame可能是明智的：

lst <- c("2,1","7,10","11,0","7,0","10,0","1,1","1,0","4,0","4,1","0,1","6,0")
DF <- read.table(text = do.call(paste, list(lst, collapse = "\n")), sep = ",")
which(DF$V1 == 1L | DF$V2 == 1L)
#[1]  1  6  7  9 10