Data.table 和 R 中的变量

Question

cad <- data.table(name)

y <- colnames(cad)[1]

cad <- add_row(cad, y = 100)

Error: New rows can't add columns. x Can't find column y in .data .

Answer 1

It needs evaluation to get the value

library(data.table)
library(tibble)
add_row(cad, !! y := 100)

-output

#   col1 col2
#1:    1    6
#2:    2    7
#3:    3    8
#4:    4    9
#5:    5   10
#6:  100   NA

data

cad <- data.table(col1 = 1:5, col2 = 6:10)
y <- colnames(cad)[1]