select multiple ranges of columns in data.table using column names [duplicate]

Question

I can select multiple ranges of columns in a data.table using a numeric vector like c(1:5,27:30). Is there any way to do the same with column names? For example, in some form similar to col1:col5,col27:col30?

Answer 1

You can with dplyr:

df <- data.frame(a=1, b=2, c=3, d=4, e=5, f=6, g=7)
dplyr::select(df, a:c, f:g)

a b c f g
1 2 3 6 7

Answer 2

I am not sure if my answer is efficient, but I think that could give you a workaround at least in case you need to work with data.table. My proposal is to use data.table in conjunction with cbind. Thus you could have:

df <- data.frame(a=1, b=2, c=3, d=4, e=5, f=6, g=7)
multColSelectedByName<- cbind(df[,a:c],df[,f:g])
#a b c f g
#1: 1 2 3 6 7

One point that one should be careful is that if there is only one column in one of the selections, for example df[,f] then the name of this column would be something like V2 and not f. In such a case one could use:
multColSelectedByName<- cbind(df[,a:c],f=df[,f])