exams.forge.data
In exams.forge.data: Sample and Precomputed Data for Use with 'exams.forge'

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
library("exams.forge.data")

Sum of Squares Dataset

The package contains the precomputed dataset sos100, which holds integer solutions for:

$\sum_{i=1}^{k} x_i = 0$
$\sum_{i=1}^{k} x_i^2 = 100$

This dataset can be used as a basis for Pearson correlation, linear regression, or other computations requiring integer data with exact sums of squares.

data("sos100")
str(sos100)
# sum_i x_i
head(rowSums(sos100, na.rm=TRUE))
# sum_i x_i^2
head(rowSums(sos100^2, na.rm=TRUE))
# number of non-missing observations
head(rowSums(!is.na(sos100)))

Using `sos()` for other datasets

For other values of n or different maximum number of summands (nmax), use the sos() function from the exams.forge package:

library("exams.forge")   # version 1.0.12 is required
# Retrieve or compute the dataset for n = 200
sos200 <- sos(200)
# With a custom nmax
sos_custom <- sos(150, nmax = 12)

This function will attempt to load the dataset from the package, a cached location, GitHub, or compute it on the fly if necessary.

Available Exercises

Note:

All exercises are provided in German, and not all of them have appeared on exams.
Some exercises require the installation of additional R packages.
Several exercises apply the same calculation methods but in different contexts.
The quality of the exercises may vary, and certain difficulties often become apparent only during the exam.

Exercises:

on Github you can find an overview of all exercises included in the package, organized by topic (directory).

library("knitr")
files <- list.files(path = system.file("aufgaben", package = "exams.forge.data"), pattern = "\\.Rmd$", recursive = TRUE, full.names = FALSE)
tab   <- table(dirname(files))
df    <- data.frame(Topic=names(tab), Exercises=as.integer(tab))               
kable(df, format = "markdown")

Exploring Exercises with `view()`

The view() function is designed to help users explore and render exercises included in the exams.forge.data package. It provides a fully scriptable interface for browsing topics, listing exercises, and optionally rendering them to PDF or HTML, without relying on interactive menus.

Key Features

List available topics

head(view("topic"))

Returns a character vector of all exercise topics (i.e., subdirectories under aufgaben/). This helps users understand the structure of the exercises and pick a topic of interest.

List exercises in a topic or matching a pattern

head(view("file", pattern = "ttest"))

Returns exercise filenames relative to the subdirectory aufgaben/ in the package.

pattern can filter by directory names (topics) or, if topic = FALSE, by content inside exercises.
This allows you to quickly locate exercises relevant to a specific concept or statistical test.
Render exercises to HTML

view("html", pattern = "hyper")

Uses exams2html() to render the selected exercises. Output is silently generated, suppressing messages and warnings.

Render exercises to PDF

view("pdf", pattern = "ttest")

Uses exams2pdf() to render the selected exercises to PDF. A plain LaTeX template is applied, and messages/warnings are suppressed to avoid console clutter.

Parameters

action: "topic", "file", "pdf", or "html". Determines what the function returns or does.
pattern: Optional regular expression to filter files or topics.
topic: Logical; if TRUE (default), pattern is applied to topic (directory) names; if FALSE, pattern is applied to file contents.
...: Additional arguments passed to grepl() for filtering.

Workflow Example

# 1. List all topics
topics <- view("topic")

# 2. Select exercises from a specific topic
files <- view("file", pattern = "ttest", topic = TRUE)

# 3. Render them to HTML
view("html", pattern = "ttest")

This approach allows users to explore hundreds of exercises efficiently, filter by topic or content, and generate outputs in multiple formats without manual interaction.

Render All Exercises

To render all exercises (on my computer, this takes roughly 1 minute), use the following code:

library("exams.forge")
files <- list.files(path=system.file("aufgaben", package="exams.forge.data"), 
                    pattern="\\.Rmd$", recursive = TRUE, full.names = TRUE)
# Render all 500+ exercises
exams2html(files)   
# Render all exercises as PDF using a custom LaTeX template
# (required because 'exams' does not support \usepackage[xtable]{xcolor})
exams2pdf(files, template=system.file("aufgaben", "plain.tex", package="exams.forge.data"))

Notes:

You may see warnings such as:
In search_files(file, dir = dir, recursive = recursive) : The following files are found more than once, first match used: ...
LaTeX Warning: 'h' float specifier changed to 'ht'.

These warnings are generally harmless and can be safely ignored.