How to scale data frame but retain type of dataframe?

Question

Built-in function scale will standardize each column of dataframe,but it will transformation original data frame into matrix.How to fix it?What if I just want to standardize only some columns?

Answer 1

There's kind of two questions here. The first, how to insert into a data.frame without losing the data.frame structure. In this case use [<- like so:

df <- data.frame(a=1:3, b=10:12, c=20:22)
df[] <- scale(df)
df
#   a  b  c
#1 -1 -1 -1
#2  0  0  0
#3  1  1  1

This is covered in a lot more detail here: R: Easy assignments with empty square brackets? x[]<-

The second question is how to update a subset of a data.frame. Again, use [<- but this time match the selections on the left and right sides of the <- :

df <- data.frame(a=1:3, b=10:12, c=20:22)
df[1:2] <- scale(df[1:2])
df
#   a  b  c
#1 -1 -1 20
#2  0  0 21
#3  1  1 22