How to subset a column of data.frame with a varible?

Question

As we know, it is each to subset a column by a $ sign and the name of a column.

df <- data.frame(matrix(rnorm(12),4,3))
df$X1

what if I want to subset a column with a variable?

a="X1"
df$a

You can do `df[df$a == 'X1']` – reusen Aug 25 '20 at 12:57 — reusen, Aug 25 '20 at 12:57

score 1 · Answer 1 · answered Aug 25 '20 at 12:55

1

> df[, a]
[1] -1.7170952  0.4502299 -2.5959374 -1.3582197

answered Aug 25 '20 at 12:55

BellmanEqn

score 0 · Answer 2 · answered Aug 25 '20 at 12:55

0

You can have the same output with this format:

> df$X1
[1]  0.1591573  1.3328099 -0.2382000 -0.7364309
> df[,a]
[1]  0.1591573  1.3328099 -0.2382000 -0.7364309

answered Aug 25 '20 at 12:55

Terru_theTerror

2 Answers2