Creating a data frame from a list of lists

Question

I'm have a list of lists, and I'm looking to turn this into a data frame where each sub-list is a row, and each element of the sub-lists are columns. I have a working solution, but it doesn't feel efficient.

# Sample data
data <- list(structure(list(pop_size = 31874, p_value = 0.373458207009449), .Names = c("pop_size", 
"p_value")), structure(list(pop_size = 41874, p_value = 0.303284884476696), .Names = c("pop_size", 
"p_value")), structure(list(pop_size = 51874, p_value = 0.249409377411917), .Names = c("pop_size", 
"p_value")), structure(list(pop_size = 61874, p_value = 0.206924824186035), .Names = c("pop_size", 
"p_value")), structure(list(pop_size = 71874, p_value = 0.172823408801164), .Names = c("pop_size", 
"p_value")))

# My solution
matrix <- matrix(NA,nrow=length(data),ncol=2)
for(i in 1:length(data)){
  matrix[i,1] <- data[[i]]$pop_size
  matrix[i,2] <- data[[i]]$p_value
}
df <- data.frame(matrix)
colnames(df) <- c("pop_size","p_value")
df
  pop_size   p_value
1    31874 0.3734582
2    41874 0.3032849
3    51874 0.2494094
4    61874 0.2069248
5    71874 0.1728234

I get the result I'd like, I'm just looking for a better way. Thanks!

Edit Turns out this was already answered in a different thread. I personally found this to be the best solution.

library(plyr)
df <- ldply(data, data.frame)

Also nice is `dplyr::bind_rows`, which isn't listed in the other question. — alistaire, Jun 20 '16 at 15:52

score 3 · Answer 1 · answered Jun 20 '16 at 15:33

3

 df <- data.frame(matrix(unlist(data), nrow=5, byrow=T))

This should solve your problem

answered Jun 20 '16 at 15:33

Shweta Kamble

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score 2 · Answer 2 · answered Jun 20 '16 at 15:32

2

This should work:

df <- matrix(unlist(data),ncol=2,byrow=T)

answered Jun 20 '16 at 15:32

Buzz Lightyear

824
1
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score 1 · Answer 3 · answered Jun 20 '16 at 15:30

1

You can try this:

do.call(rbind, lapply(data, as.data.frame))
  pop_size   p_value
1    31874 0.3734582
2    41874 0.3032849
3    51874 0.2494094
4    61874 0.2069248
5    71874 0.1728234

answered Jun 20 '16 at 15:30

Psidom

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2

or simply `do.call(rbind.data.frame, data)` – rawr Jun 20 '16 at 15:39

Creating a data frame from a list of lists

3 Answers3