Outline
我正在试图在一个列表中找到一个数字,这些数字等于一个给定的和.我设法用简洁的语法计算了数字及其总和的所有组合.但我无法将生成的嵌套列表重新构造为不同类型的嵌套列表.
Minimal example
library(data.table)
library(purrr)
# raw data and basic operation
dt <- data.table(
amount = c(2,5,9)
)[,
`:=`(
# nesting combinations into the data.table
amount.set = map(1:.N,function(x) combn(amount,x)),
sum = map(1:.N,function(x) colSums(combn(amount,x)))
)
]
# desired structure of nested list
desired.output <- data.table(
sum = c(2,5,9,7,11,14,16),
amount.set = list(c(2),c(5),c(9),c(2,5),c(2,9),c(5,9),c(2,5,9))
)
我怎么才能在desired.output
里实现这个 struct 呢?