Converting data frame into a list of lists in R

Question

I would like to turn data.frame like this one:

dat = data.frame (
    ConditionA = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1),
    ConditionB = c(1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5),
    X = c(460, 382, 468, 618, 421, 518, 655, 656, 621, 552, 750, 725, 337, 328, 342, 549, 569, 523, 469, 429),
    Y = c(437, 305, 498, 620, 381, 543, 214, 181, 183, 387, 439, 351, 327, 268, 276, 178, 375, 393, 312, 302)
)

into a list of lists like this (or similar):

lst = list(
    list(
        c(460, 382, 468, 618),
        c(437, 305, 498, 620)
    ),
    list(
        c(421, 518, 655, 656, 621),
        c(381, 543, 214, 181, 183)
    ),
    list(
        c(552, 750, 725),
        c(387, 439, 351)
    ),
    list(
        c(337, 328, 342, 549),
        c(327, 268, 276, 178)
    ),
    list(
        c(569, 523, 469, 429),
        c(375, 393, 312, 302)
    )
)

> lst
[[1]]
[[1]][[1]]
[1] 460 382 468 618

[[1]][[2]]
[1] 437 305 498 620


[[2]]
[[2]][[1]]
[1] 421 518 655 656 621

[[2]][[2]]
[1] 381 543 214 181 183


[[3]]
[[3]][[1]]
[1] 552 750 725

[[3]][[2]]
[1] 387 439 351

. . .

What would be the most efficient way to make such a conversion?

Why do you have two conditionA? Assuming you only have one of them: lapply(split(dat[, c("X", "Y")], dat$ConditionA), as.list) — Alexis
– Alexis, Commented Jun 10, 2018 at 20:12
@Alexis I haven't seen your comment when I posted the answer. — akrun
– akrun, Commented Jun 10, 2018 at 20:29

akrun · Accepted Answer · 2018-06-10 20:53:18Z

4

We can do a split based on the 1st and 2nd columns, use drop=TRUE for removing the combinations with 0 elements and convert to list

lapply(split(dat[-(1:2)], dat[1:2], drop = TRUE), as.list)

Or using tidyverse

library(tidyverse)
dat %>% 
    group_by(ConditionA, ConditionA.1) %>% 
    nest %>%
    mutate(data = map(data, as.list)) %>%
    pull(data)

edited Jun 10, 2018 at 20:53

answered Jun 10, 2018 at 20:12

akrun

891k38 gold badges590 silver badges700 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Sathish · Accepted Answer · 2018-06-10 20:16:46Z

2

May be this using data.table

Data:

dat = data.frame (
  ConditionA = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1),
  ConditionB = c(1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5),
  X = c(460, 382, 468, 618, 421, 518, 655, 656, 621, 552, 750, 725, 337, 328, 342, 549, 569, 523, 469, 429),
  Y = c(437, 305, 498, 620, 381, 543, 214, 181, 183, 387, 439, 351, 327, 268, 276, 178, 375, 393, 312, 302)
)

Code:

library('data.table')
setDT(dat)
dat[, list(list(as.list(.SD))),by = .(ConditionA, ConditionB)][, V1]

or this

dat[, list(list(list(.SD))),by = .(ConditionA, ConditionB)][, V1]

answered Jun 10, 2018 at 20:16

Sathish

12.7k3 gold badges46 silver badges60 bronze badges

Comments

Onyambu · Accepted Answer · 2018-06-10 20:43:33Z

2

c(by(dat[3:4],dat[1:2],as.list))
[[1]]
[[1]]$X
[1] 460 382 468 618

[[1]]$Y
[1] 437 305 498 620


[[2]]
[[2]]$X
[1] 421 518 655 656 621

[[2]]$Y
[1] 381 543 214 181 183


[[3]]
[[3]]$X
[1] 552 750 725

[[3]]$Y
[1] 387 439 351

 . . . .

answered Jun 10, 2018 at 20:43

Onyambu

80.3k3 gold badges29 silver badges65 bronze badges

Collectives™ on Stack Overflow

Converting data frame into a list of lists in R

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related