Question

The _________ function is used to generate summary statistics from the data frame within strata defined by a variable.

(a) groupby()

(b) group()

(c) group_by()

(d) arrange

This question was posed to me in a national level competition.

The origin of the question is dplyr topic in portion R – Data Storage, Formats, Objects and Operations of R Programming

Answer 1

The correct option is (c) group_by()

Easiest explanation: The general operation here is a combination of splitting a data frame into separate pieces defined by a variable or group of variables (group_by()), and then applying a summary function across those subsets (summarize()).