Here you can find some simple interesting concepts for coding in R.
How to select all numeric columns in a data frame?
df = data.frame(x = c(1:3),
y = c('A','B','C'),
z = c(0.1, 0.2, 0.3))
df## x y z
## 1 1 A 0.1
## 2 2 B 0.2
## 3 3 C 0.3# Select all numeric columns
df[sapply(df,is.numeric)]## x z
## 1 1 0.1
## 2 2 0.2
## 3 3 0.3