print methods, truncate output of data

[sbrockhaus]

I think it would be very nice if the print-methods (print.mboost and print.glmboost) would have a check so that they do not print very long calls directly into the console. This is especially an issue when using gamboostLSS / mboostLSS as in this case at the moment the whole dataset is printed.

A small example in R showing the problem and giving a possible solution (model fit taken from the help of gamboostLSS):

library(gamboostLSS)

### Data generating process:
set.seed(1907)
x1 <- rnorm(1000)
x2 <- rnorm(1000)
x3 <- rnorm(1000)
x4 <- rnorm(1000)
x5 <- rnorm(1000)
x6 <- rnorm(1000)
mu    <- exp(1.5 +1 * x1 +0.5 * x2 -0.5 * x3 -1 * x4)
sigma <- exp(-0.4 * x3 -0.2 * x4 +0.2 * x5 +0.4 * x6)
y <- numeric(1000)
for( i in 1:1000)
  y[i] <- rnbinom(1, size = sigma[i], mu = mu[i])
dat <- data.frame(x1, x2, x3, x4, x5, x6, y)

### linear model with y ~ . for both components: 400 boosting iterations
model <- glmboostLSS(y ~ ., families = NBinomialLSS(), data = dat,
                     control = boost_control(mstop = 400),
                     center = TRUE)

####### very long output in console
model$mu

####### I do not have a nice solution, but something that works for my problem 
####### only one line added to print.glmboost

print.glmboost <- function(x, ...) {

  cat("\n")
  cat("\t Generalized Linear Models Fitted via Gradient Boosting\n")
  cat("\n")
  if (!is.null(x$call)){
    ## EXTRA LINE
    if(length(deparse(x$call$data))>20) x$call$data <- deparse(x$call$data, nlines=1)
    ## EXTRA LINE
    cat("Call:\n", deparse(x$call), "\n\n", sep = "")
  } 
  show(x$family)
  cat("\n")
  cat("Number of boosting iterations: mstop =", mstop(x), "\n")
  cat("Step size: ", x$control$nu, "\n")
  cat("Offset: ", x$offset, "\n")
  cat("\n")
  cat("Coefficients: \n")
  cf <- coef(x)
  attr(x, "offset") <- NULL
  print(cf)
  cat("\n")
  invisible(x)
}

####### now the output of the data is truncated, and I get a nice overview on the model specification
model$mu

[hofnerb]

Use the proposed solution above to make sure that the printed call is not overly rich. In gamboostLSS however, we need to modify the call by replacing the actual data with the name of the data set provided.