使用R中的开始和停止索引创建数据帧列表

Question

In R, take any large data frame (example 300,000 rows and 30 columns). I want to create a list of data frames using start and stop index values I have stored in another data frame (two columns, first column are the start values and the second contains the stop values.) The number of rows in the start-stop df will be the number of dataframes stored in the list (in this small example, 6). To me there sounds like there might be an easy function to do this, but before I've always created lists of data frames before using the split command or with different conditional statements, so I did some research but couldn't find a solution. Also, I'm double looping below, which is not preferable. Any help greatly appreciated!

Example of start, stop data frame

> df
     headID tailID
[1,]    688    704
[2,]   2576   2583
[3,]   4005   4018
[4,]   4336   5761
[5,]   5762   7201
[6,]   7202   8641

So I'm thinking something like (pseudo-code):

n <- length(bigDF)
subList <- list()
start.idx <- NA
obs <- dim(bigDF)
for(i in 2:obs){
  for(j in 1:df) {
    start.idx <- df$headID[j]
  }                                                                                    
  else if 
end.idx <- df$tailID[j]
subMat <- bigDF[start.idx:end.idx,]
subList[[counter]] <- subMat
start.idx <- NA
counter <- counter + 1
  }
}
}

Answer 1

I would write a function and apply it...

f <- function(x, data) {
    data[x[1]:x[2],]
}

apply(df, 1, f, bigDF)