df <- data.frame(a = 1:10, y = rnorm(10), l = letters[1:10])
df
## a y l
## 1 1 1.43638070 a
## 2 2 0.08001122 b
## 3 3 -0.13754592 c
## 4 4 -0.58091990 d
## 5 5 1.15955232 e
## 6 6 0.81428658 f
## 7 7 -1.01419810 g
## 8 8 0.52744843 h
## 9 9 0.19757766 i
## 10 10 0.60040306 j
df[, c("y", "a")]
## y a
## 1 1.43638070 1
## 2 0.08001122 2
## 3 -0.13754592 3
## 4 -0.58091990 4
## 5 1.15955232 5
## 6 0.81428658 6
## 7 -1.01419810 7
## 8 0.52744843 8
## 9 0.19757766 9
## 10 0.60040306 10
df[, c(2, 1)]
## y a
## 1 1.43638070 1
## 2 0.08001122 2
## 3 -0.13754592 3
## 4 -0.58091990 4
## 5 1.15955232 5
## 6 0.81428658 6
## 7 -1.01419810 7
## 8 0.52744843 8
## 9 0.19757766 9
## 10 0.60040306 10
df[, 2, drop = FALSE]
## y
## 1 1.43638070
## 2 0.08001122
## 3 -0.13754592
## 4 -0.58091990
## 5 1.15955232
## 6 0.81428658
## 7 -1.01419810
## 8 0.52744843
## 9 0.19757766
## 10 0.60040306
df[[1]]
## [1] 1 2 3 4 5 6 7 8 9 10
1:10
## [1] 1 2 3 4 5 6 7 8 9 10
print(df)
## a y l
## 1 1 1.43638070 a
## 2 2 0.08001122 b
## 3 3 -0.13754592 c
## 4 4 -0.58091990 d
## 5 5 1.15955232 e
## 6 6 0.81428658 f
## 7 7 -1.01419810 g
## 8 8 0.52744843 h
## 9 9 0.19757766 i
## 10 10 0.60040306 j