dataframe - Subset R data.frame by index and name in one line -

sample data.frame:

structure(list(a = c(1, 2, 3), b = c(4, 5, 6), c = c(7, 8, 9)), .names = c("a", "b", "c"), row.names = c(na, -3l), class = "data.frame") 

output:

df #   b c # 1 1 4 7 # 2 2 5 8 # 3 3 6 9 

i'd first , third columns, want subset name , column index.

df[, "a"] # [1] 1 2 3  df[, 3] # [1] 7 8 9  df[, c("a", 3)] # error in `[.data.frame`(df, , c("a", 3)) : undefined columns selected  df[, c(match("a", names(df)), 3)] #   c # 1 1 7 # 2 2 8 # 3 3 9 

are there functions or packages allow clean/simple syntax, in third example, while achieving result of fourth example?

mabe use dplyr?

for interactive use - i.e., if know ahead of time name of column want select

library(dplyr) df %>% select(a, 3) 

if not know name of column in advance, , want pass variable,

x <- names(df)[1] x [1] "a"  df %>% select_(x, 3) 

either way output is

#  c #1 1 7 #2 2 8 #3 3 9