nest | R Documentation |
Analogous function for nest
and unnest
in tidyr.
unnest
will automatically remove other list-columns except for the
target list-columns (which would be unnested later). Also, squeeze
is
designed to merge multiple columns into list column.
nest(.data, ..., mcols = NULL, .name = "ndt") unnest(.data, ...) squeeze(.data, ..., .name = "ndt") chop(.data, ...) unchop(.data, ...)
.data |
data.table, nested or unnested |
... |
The variables for nest group(for |
mcols |
Name-variable pairs in the list, form like |
.name |
Character. The nested column name. Defaults to "ndt".
|
In the nest
, the data would be nested to a column named 'ndt',
which is short for nested data.table.
The squeeze
would not remove the originial columns.
The unchop
is the reverse operation of chop
.
These functions are experiencing the experimental stage, especially
the unnest
. If they don't work on some circumtances, try tidyr
package.
data.table, nested or unnested
https://www.r-bloggers.com/much-faster-unnesting-with-data-table/
https://stackoverflow.com/questions/25430986/create-nested-data-tables-by-collapsing-rows-into-new-data-tables
nest
, chop
mtcars = as.data.table(mtcars) iris = as.data.table(iris) # examples for nest # nest by which columns? mtcars %>% nest(cyl) mtcars %>% nest("cyl") mtcars %>% nest(cyl,vs) mtcars %>% nest(vs:am) mtcars %>% nest("cyl|vs") mtcars %>% nest(c("cyl","vs")) # nest two columns directly iris %>% nest(mcols = list(petal="^Pe",sepal="^Se")) # nest more flexibly iris %>% nest(mcols = list(ndt1 = 1:3, ndt2 = "Pe", ndt3 = Sepal.Length:Sepal.Width)) # examples for unnest # unnest which column? mtcars %>% nest("cyl|vs") %>% unnest(ndt) mtcars %>% nest("cyl|vs") %>% unnest("ndt") df <- data.table( a = list(c("a", "b"), "c"), b = list(c(TRUE,TRUE),FALSE), c = list(3,c(1,2)), d = c(11, 22) ) df df %>% unnest(a) df %>% unnest(2) df %>% unnest("c") df %>% unnest(cols = names(df)[3]) # You can unnest multiple columns simultaneously df %>% unnest(1:3) df %>% unnest(a,b,c) df %>% unnest("a|b|c") # examples for squeeze # nest which columns? iris %>% squeeze(1:2) iris %>% squeeze("Se") iris %>% squeeze(Sepal.Length:Petal.Width) # examples for chop df <- data.table(x = c(1, 1, 1, 2, 2, 3), y = 1:6, z = 6:1) df %>% chop(y,z) df %>% chop(y,z) %>% unchop(y,z)
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