Bracket notation subsetting returns inconsistent results between data.frame and data_frame

[Thomas Hopper]

I just spent some time trying to fix some graphing errors in my code. After pulling my hair out for a while, I eventually discovered that the errors came about because I had changed some of my code from using base R functions to using dplyr data_frame objects (class "tbl_df" "tbl" "data.frame"). data_frames don't treat bracket subsetting quite the same as a data.table.

I'm wondering if this is deliberate or an error that I should be reporting? I haven't seen it 

Example:

df <- data.frame(a = runif(5), b = rnorm(5), c = letters[1:5], stringsAsFactors = FALSE)

df[1]   # Returns a data.frame slice

df[,1]  # Returns a vector

df[[1]] # Returns a vector

library(dplyr)

df <- data_frame(a = runif(5), b = rnorm(5), c = letters[1:5], stringsAsFactors = FALSE)

df[1]   # Returns a data.frame slice, same as with data.table

df[,1]  # Returns a data.frame slice, DIFFERENT than data.table

df[[1]] # Returns a vector, same as with data.table

Is this expected? Is there a reason for this difference that I'm missing?

Thanks,

Tom

[Ista Zahn]

Deliberate. See https://cran.r-project.org/web/packages/dplyr/vignettes/data_frames.html and ?tbl_df

Best,
Ista

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[Thomas Hopper]

Thank you!