How to convert a list of dataframes in to a single dataframe using R

Question

I have a code which results as a list of data frames, which I want to convert to a single data frame.

Here's an example :

list_Of_Data_Frames <- vector(mode = "list", length = 100)
for (i in 1:100) {
    list_Of_Data_Frames[[i]] <- data.frame(a=sample(letters, 500, rep=T),
                             b=rnorm(500), c=rnorm(500))
}

I am currently using this:

  data <- do.call("rbind", list_Of_Data_Frames)

Answer 1

You can use the plyr function:

data <- ldply(list_Of_Data_Frames, data.frame)

This is a little slower than the original:

system.time({ data <- do.call("rbind", list_Of_Data_Frames) })
   user  system elapsed 
   0.25    0.00    0.25  system.time({ data2 <- ldply(list_Of_Data_Frames, data.frame) })
   user  system elapsed 
   0.30    0.00    0.29 identical(data, data2)
[1] TRUE

Comments

Is it possible to sort or order or group_by  an output data.frame by a column "a" values ? Some of them are reapeted and scattered i.e.:

p, j, d, etc.

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You can order or sort data frame using arrange function in the dplyr package or using order or sort method.

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Thanks, @Kiran. Can you please make this an answer? It'll be easier for other readers to understand and I can upvote your answer.. Thanks!

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Thanks, @Laila. I'm glad it helped!!

I commented on the question because it is not the answer to the main question.