Moving from deprecated summarize_ to new summarize in dplyr

Question

I have a function that calculates the means of a grouped database for a column which is chosen based on the content of a variable VarName. The current function uses

Answer 1

Turning this into a function and generalizing for arbitrary data, grouping variable, and value variable:

library(tidyverse)

means <- function(data, group, value) {

  group = enquo(group)
  value = enquo(value)
  value_name = paste0("mean_", value)[2]

  data %>% group_by(!!group) %>% 
    summarise(!!value_name := mean(!!value, na.rm=TRUE))
}

means(dat, Grade, Things)

  Grade mean_Things
  <dbl>       <dbl>
1  2.00        90.0
2  3.00        77.5

If I understand your comment, how about the function below, which takes a string for the value argument:

means <- function(data, group, value) {

  group = enquo(group)
  value_name = paste0("mean_", value)
  value = sym(value)

  data %>% group_by(!!group) %>% 
    summarise(!!value_name := mean(!!value, na.rm=TRUE))
}

VarName = "Things"

means(dat, Grade, VarName)

  Grade mean_Things
  <dbl>       <dbl>
1  2.00        90.0
2  3.00        77.5

Since the function is generalized, you can do this with any data frame. For example:

means(mtcars, cyl, "mpg")

    cyl mean_mpg
  <dbl>    <dbl>
1  4.00     26.7
2  6.00     19.7
3  8.00     15.1

You can generalize the function still further. For example, this version takes an arbitrary number of grouping columns:

means <- function(data, value, ...) {

  group = quos(...)
  value_name = paste0("mean_", value)
  value = sym(value)

  data %>% group_by(!!!group) %>% 
    summarise(!!value_name := mean(!!value, na.rm=TRUE))
}

VarName = "Things"

means(dat, VarName, students, Grade)

  students Grade mean_Things
  <fct>    <dbl>       <dbl>
1 a         2.00        90.0
2 b         2.00       100  
3 c         2.00        80.0
4 d         3.00        75.0
5 e         3.00        80.0

Answer 2

Use !! with as.name or as.symbol:

dat %>% 
    group_by(Grade) %>% 
    summarize(means = mean(!!as.name(VarName), na.rm=T))
    # or summarize(means = mean(!!as.symbol(VarName), na.rm=T))

# A tibble: 2 x 2
#  Grade means
#  <dbl> <dbl>
#1  2.00  90.0
#2  3.00  77.5