The objective of this document is to be a reference for topics about the R programming language itself, not so much about statistics or data manipulation.
It’s a work in progress and the first example below is good to demonstrate the kind of matter that will be treated here.
The code below demonstrates how to make an indirect reference to ‘key = value’ arguments in dplyr functions:
suppressPackageStartupMessages(library(dplyr))
cols = names(iris)[2:4] # select remaining columns
col_syms = syms(cols) # create symbols from strings
summary_vars <- lapply(col_syms, function(col) {
expr(last(!!col)) # expression that should be evaluated in summarise
})
names(summary_vars) = cols # new column names (set old names)
iris %>%
group_by(Species) %>%
summarise(Sepal.Length = mean(Sepal.Length), !!!summary_vars) # open expressions## `summarise()` ungrouping output (override with `.groups` argument)## # A tibble: 3 x 5
## Species Sepal.Length Sepal.Width Petal.Length Petal.Width
## <fct> <dbl> <dbl> <dbl> <dbl>
## 1 setosa 5.01 3.3 1.4 0.2
## 2 versicolor 5.94 2.8 4.1 1.3
## 3 virginica 6.59 3 5.1 1.8