create a list of dataframes from one dataframe based on unique values of a column [duplicate]

Question

Consider the following data:

myd <- dput(myd)
structure(list(group = c("g1", "g1", "g1", "g1", "g1", "g2", 
"g2", "g2", "g2", "g3", "g3", "g3", "g3", "g3"), X1 = c(0, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0), X2 = c(1, 1, 1, 1, 1, 0, 
0, 0, 0, 1, 0, 0, 2, 0), X3 = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 
1, 1, 2, 1), X4 = c(1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 2, 1), 
    X5 = c(1, 0, 0, 0, 0, 2, 2, 2, 2, 2, 0, 1, 2, 2), X6 = c(2, 
    2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 1, 2, 2), X7 = c(2, 2, 2, 2, 
    2, 2, 2, 2, 1, 1, 0, 2, 2, 2), X8 = c(1, 1, 1, 1, 1, 1, 1, 
    1, 1, 1, 1, 1, 2, 1), X9 = c(2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
    1, 1, 0, 2), X10 = c(1, 1, 1, 1, 1, 2, 2, 2, 2, 0, 0, 2, 
    1, 2), X11 = c(2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 1, 2, 2), 
    X12 = c(1, 1, 1, 1, 1, 2, 2, 2, 2, 0, 1, 0, 1, 2), X13 = c(2, 
    2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 1, 0, 2), X14 = c(0, 0, 0, 
    0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1), X15 = c(0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 1, 0, 0), X16 = c(1, 1, 0, 0, 0, 1, 1, 
    1, 1, 1, 0, 2, 1, 1), X17 = c(2, 2, 2, 2, 2, 1, 1, 1, 1, 
    1, 0, 2, 1, 1), X18 = c(2, 2, 2, 2, 2, 1, 1, 1, 1, 0, 1, 
    1, 0, 1), X19 = c(2, 2, 2, 2, 2, 0, 0, 0, 0, 0, 1, 0, 1, 
    0), X20 = c(2, 2, 2, 2, 2, 0, 0, 0, 0, 0, 1, 1, 0, 0), X21 = c(1, 
    1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1), X22 = c(0, 0, 0, 
    0, 0, 1, 1, 1, 1, 1, 0, 2, 0, 1), X23 = c(1, 1, 1, 1, 1, 
    1, 1, 1, 1, 1, 2, 0, 1, 1), X24 = c(1, 1, 1, 1, 1, 1, 1, 
    1, 1, 1, 0, 1, 2, 1), X25 = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 1, 0, 2, 0), X26 = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 
    0, 2, 1)), row.names = c("S1", "S2", "S3", "S4", "S5", "S6", 
"S7", "S8", "S9", "S10", "S11", "S12", "S13", "S14"), class = "data.frame")

I looks like that :

   group X1 X2 X3 X4
S1    g1  0  1  1  1
S2    g1  0  1  1  1
S3    g1  0  1  1  1
S4    g1  0  1  1  0
S5    g1  0  1  1  0

I want to create a list of dataframes based on the unique values of myd$group which are 3 (g1,g2,g3) so every element of a list will be a subset of myd dataframe with unique values of myd$group. I know how to do it using a for loop but I think for loops in R are slow, please correct me if I am wrong about that. Thus a solution with some apply family or dplyr package would be very welcome.

akrun · Accepted Answer · 2019-08-16 13:20:52Z

3

We can use split to create a list of data.frames

lst1 <- split(myd, myd$group)

In tidyverse, it can be

library(dplyr)
myd %>%
   group_split(group)

answered Aug 16, 2019 at 13:20

akrun

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