R：如何解决无效的下标类型“列表”

Question

Origianl dataframe is

id status name ...
1  0      V
1  0      S
1  1      V
1  0      V
2  0      V
2  1      V
2  1      S
3  0      V
3  1      S
4  1      S
4  0      V
4  1      V

Out of this, I expect to fetch id 2 and 3 as in their subset I have a "0-V" combination followed by "1-S"

I have split that into a list of dataframes and I want to fetch the id's for some particular conditions on those dataframes but I get the error

invalid subscript type 'list'

The structure is like follows

"1"
id status name ...
1  0      V
1  0      S
1  1      V
1  0      V

"2"
id status name ...
2  0      V
2  1      V
2  1      S
...

Now I need to find a condition such that I get the id where there is a record of 0 status and name 'V' followed by a 1 status and name "S" like for id 2.

For doing so, I'm trying to write a function for sapply but I'm not able to subscript the data as I'm assuming it to be

Here is the code

q4 <- result1[,c("id", "name", "date", "status")]

lstQ <- split(q4, result1$id)


f3 <- function(g) {
  g[g$status == 0 & g$name == "V",]
} 

 e <- as.data.frame(names(lstQ)[sapply(lstQ, f3)])

How can I subscript my dataframe to get the desired check condition?

Answer 1

Your data:

DF <- read.table(text = "id status name
                 1  0      V
                 1  0      S
                 1  1      V
                 1  0      V
                 2  0      V
                 2  1      V
                 2  1      S
                 3  0      V
                 3  1      S
                 4  1      S
                 4  0      V
                 4  1      V", header = TRUE)

Let's write a function:

fun <- function(DF) {
  one <- DF$status == 0 & DF$name == "V"
  two <- DF$status == 1 & DF$name == "S"

  #Is two TRUE after one is TRUE?
  if (any(one) && any(two)) return(any(which(two) > which.max(one)))
  return(FALSE)
}

Use a "group by" type function. I like data.table, others prefer dplyr:

library(data.table)
setDT(DF)
DF[, fun(.SD), by = id]
#   id    V1
#1:  1 FALSE
#2:  2  TRUE
#3:  3  TRUE
#4:  4 FALSE

You can then use setDF if you prefer or keep working with data.table and its syntax. Subsetting could be the trivial next step.