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rlistdataframenestedrbind

Combine data frames from a nested list

I am having trouble combining data frames that are contained in a nested list with a concise syntax. I have a nested list of the following form:

nestedList <- lapply(1:3,function(y){
  lapply(1:8,function(z){
    data.frame(matrix(rnorm(20), nrow=10))
  })
})

So nestedList contains 3 lists that each contain 8 lists with a data frame. I would like to combine the lists as follows:

tmp1 <- nestedList[[1]][[1]]
tmp2 <- nestedList[[2]][[1]]
tmp3 <- nestedList[[3]][[1]]

expectedResult <- rbind(tmp1,tmp2,tmp3)

I would have expected that the following syntax is valid, but apparently it isn't:

unexpectedResult <- rbind(nestedList[[1:3]][[1]])
Solution

  • Try this. 

    foo <- lapply(nestedList, function(x) x[[1]])
this <- do.call("rbind", foo)