R语言基础-数据列添加与删除

Python014

R语言基础-数据列添加与删除,第1张

DT = data.table(x=rep(c("a","b","c"),each=3),

y=c(1,3,6), v=1:9)

DT[, a := 'k'] # 整列添加 ‘k’

DT[, c := 8] # 整列添加数字8

DT[,d:=9L] # 整列添加长整型9

DT[, e := d + 2]

DT[2,d:=10L] # 精确修改2行，d列数字为10

DT[, e := d + 2] # 数据中已经包含e列则是对这列数据的修改

DT[, c('f', 'g') := list( d + 1, c)]

DT[, ':=' ( f = d + 1, g = c)]# 同上

DT[,c:=NULL] # 单列删除

DT[, c('d', 'e', 'f', 'g'):=NULL] # 多列删除

data <- data[,-(1:5)]

library(dplyr)

data <- select(data,-3)

data <- select(data,-1,-2,-3,-4,-5)

data <- select(data,-lieming)

data <- select(data,-c(lieming1,lieming2))