R、 data.table:对名称存储在向量中的所有列求和
从data.tableR、 data.table:对名称存储在向量中的所有列求和,r,data.table,evaluation,expression-evaluation,R,Data.table,Evaluation,Expression Evaluation,从data.tabled中,例如 require(data.table) d = data.table(a = 1:4, b = 11:14, c = 21:24, group = c(1,1,2,2)) 我想将存储在向量varsToSum中的所有变量的名称按group的唯一值求和 varsToSum = c("a", "b") 对于上述d和varsToSum,预期结果为 d[,list(a = sum(a), b = sum(b)),list(group)] group a b
d
中,例如
require(data.table)
d = data.table(a = 1:4, b = 11:14, c = 21:24, group = c(1,1,2,2))
我想将存储在向量varsToSum
中的所有变量的名称按group
的唯一值求和
varsToSum = c("a", "b")
对于上述d
和varsToSum
,预期结果为
d[,list(a = sum(a), b = sum(b)),list(group)]
group a b
1: 1 3 23
2: 2 7 27
相关职位:
d[, lapply(.SD, sum), by = group, .SDcols = varsToSum]
group a b
1: 1 3 23
2: 2 7 27