Evaluate an expression and log results

log_eval(expr, level = TRACE, multiline = FALSE)

Arguments

expr

R expression to be evaluated while logging the expression itself along with the result

level

log_levels

multiline

setting to FALSE will print both the expression (enforced to be on one line by removing line-breaks if any) and its result on a single line separated by =>, while setting to TRUE will log the expression and the result in separate sections reserving line-breaks and rendering the printed results

Examples

if (FALSE) { log_eval(pi * 2, level = INFO) ## lowering the log level threshold so that we don't have to set a higher level in log_eval log_threshold(TRACE) log_eval(x <- 4) log_eval(sqrt(x)) ## log_eval can be called in-line as well as returning the return value of the expression x <- log_eval(mean(runif(1e3))) x ## https://twitter.com/krlmlr/status/1067864829547999232 f <- sqrt g <- mean x <- 1:31 log_eval(f(g(x)), level = INFO) log_eval(y <- f(g(x)), level = INFO) ## returning a function log_eval(f <- sqrt) log_eval(f) ## evaluating something returning a wall of "text" log_eval(f <- log_eval) log_eval(f <- log_eval, multiline = TRUE) ## doing something computationally intensive log_eval(system.time(for(i in 1:100) mad(runif(1000))), multiline = TRUE) }