Time an expression or code chunk

Time an expression or chunk of R code with `system.time()` and return both the results of evaluating the expression and the execution time in a list.

time_this(code, time_as = c("list", "attr"))

Arguments

code	An expression or code chunk (wrapped in curly brackets) to time.
time_as	character; return the execution time and results as list elements ("list") or return results with time as an attribute ("attr").

Value

A list with elements `result` and `time`, containing the results of evaluating `code` and the execution time, respectively. If `time_as = "attr"`, the result will be returned directly with the time stored as an attribute.

Examples

# time a simple expression
time_this(mean(rnorm(1e6)))
#> $result
#> [1] 0.000685264
#> 
#> $time
#>    user  system elapsed 
#>   0.069   0.001   0.071 
#> 

# time a code chunk
time_this({
  x <- (1:1e6) / 1e6
  y = 2 * x + 1 + rnorm(x)
  lm(y ~ x)
})
#> $result
#> 
#> Call:
#> lm(formula = y ~ x)
#> 
#> Coefficients:
#> (Intercept)            x  
#>       1.001        2.000  
#> 
#> 
#> $time
#>    user  system elapsed 
#>   0.230   0.049   0.279 
#> 

# time can also be stored as an attribute
time_this(mean(rnorm(1e6)), time_as = "attr")
#> [1] -0.000592503
#> attr(,"time")
#>    user  system elapsed 
#>   0.073   0.001   0.073