Evaluate R code and mask the output by a prefix

This function is designed to insert the output of each chunk of R code into the source code without really breaking the source code, since the output is masked in comments.

tidy_eval(source = "clipboard", ..., file = "", prefix = "## ", envir = parent.frame())

Arguments

source	the input filename (by default the clipboard; see tidy_source)
...	other arguments passed to tidy_source
file	the file to write by cat; by default the output is printed on screen
prefix	the prefix to mask the output
envir	the environment in which to evaluate the code (by default the parent environment; if we do not want to mess up with the parent environment, we can set envir = NULL or envir = new.env())

Value

Evaluated R code with corresponding output (printed on screen or written in a file).

References

https://yihui.name/formatR

Examples

library(formatR)
## evaluate simple code as a character vector
tidy_eval(text = c("a<-1+1;a", "matrix(rnorm(10),5)"))
#> a <- 1 + 1
#> a
#> ## [1] 2
#> 
#> matrix(rnorm(10), 5)
#> ##             [,1]       [,2]
#> ## [1,] -0.08433889 -0.8571904
#> ## [2,] -0.55406480 -1.5247442
#> ## [3,]  0.74717660  1.9694248
#> ## [4,] -0.93481966  0.4631747
#> ## [5,] -0.46662045 -0.8561524
#> 

## evaluate a file
tidy_eval(system.file("format", "messy.R", package = "formatR"))
#> # a single line of comments is preserved
#> 1 + 1
#> ## [1] 2
#> 
#> 
#> if (TRUE) {
#>     x = 1  # inline comments
#> } else {
#>     x = 2
#>     print("Oh no... ask the right bracket to go away!")
#> }
#> 1 * 3  # one space before this comment will become two!
#> ## [1] 3
#> 
#> 2 + 2 + 2  # 'short comments'
#> ## [1] 6
#> 
#> 
#> # only 'single quotes' are allowed in comments
#> df = data.frame(y = rnorm(100), x1 = rnorm(100), x2 = rnorm(100))
#> lm(y ~ x1 + x2, data = df)
#> ## 
#> ## Call:
#> ## lm(formula = y ~ x1 + x2, data = df)
#> ## 
#> ## Coefficients:
#> ## (Intercept)           x1           x2  
#> ##      0.1742       0.0723      -0.2047  
#> ## 
#> 
#> 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 
#>     1 + 1  ## comments after a long line
#> ## [1] 23
#> 
#> 
#> ## here is a long long long long long long long long long long long long long long
#> ## long long long long long long comment