## --- Preliminaries ---
## load package and enforce par(ask = FALSE)
library("exams")
options(device.ask.default = FALSE)
## set up a temporary working directory in which all files are managed
odir <- getwd()
dir.create(mydir <- tempfile())
setwd(mydir)
## --- Step 1 ---
## exam generation
## define an exam (= list of exercises)
myexam <- list(
"tstat2.Rnw",
"ttest.Rnw",
"relfreq.Rnw",
"anova.Rnw",
c("boxplots.Rnw", "scatterplot.Rnw"),
"cholesky.Rnw"
)
## create multiple exams on the disk with different numbers of points
## per exercise (see ?exams2nops for more examples)
set.seed(403)
ex1 <- exams2nops(myexam, n = 2, dir = ".", date = "2015-07-29",
points = c(1, 1, 1, 2, 2, 3), showpoints = TRUE)
dir()
## assume the PDF exams were already printed (and possibly backed up
## in a different directory) so that they are not needed anymore
file.remove(dir(pattern = "pdf$"))
## --- Step 2 ---
## scan results
## assume two participants filled out the printed exam sheets
## and the corresponding scans are in two PNG files,
img <- dir(system.file("nops", package = "exams"), pattern = "nops_scan",
full.names = TRUE)
## copy the PNG files to the working directory
file.copy(img, to = ".")
## read the scanned images (all locally available .png files) and collect
## results in a ZIP archive (see ?nops_scan for more details)
nops_scan()
dir()
## the ZIP archive contains copies of the PNG images so that these are
## can be deleted here (possibly after backup in a different directory)
file.remove(dir(pattern = "png$"))
## -- Step 3 ---
## evaluate results
## three files are required: (a) an RDS file with the exam meta-information
## (see Step 1), (b) a ZIP file with the scanned sheets (see Step 2), (c) a
## CSV file with the student infomation (registration number, name, and some
## for of ID/username)
## here we create the CSV file on the fly but in practice this will typically
## be processed from some registration service or learning management system etc
write.table(data.frame(
registration = c("1501090", "9901071"),
name = c("Jane Doe", "Ambi Dexter"),
id = c("jane_doe", "ambi_dexter")
), file = "Exam-2015-07-29.csv", sep = ";", quote = FALSE, row.names = FALSE)
dir()
## now the exam can be evaluated creating an output data frame (also stored
## as CSV file) and individual HTML reports (stored in a ZIP file),
## as there is only exactly on CSV/RDS/ZIP file in the current directory,
## these are found automatically - furthermore an evaluation scheme without
## partial points and differing points per exercise are used
ev1 <- nops_eval(eval = exams_eval(partial = FALSE, negative = FALSE))
dir()
## inspect evaluated data
ev1
## inspect corresponding HTML reports
if(interactive()) {
unzip("nops_eval.zip")
browseURL(file.path(mydir, "jane_doe", "Exam-2015-07-29.html"))
browseURL(file.path(mydir, "ambi_dexter", "Exam-2015-07-29.html"))
}
## --- Options ---
if(interactive()) {
## below three typically needed options are discussed:
## (a) using a different evaluation strategy (here with partial credits),
## (b) using a different language (here de/German),
## (c) an error of the participant when filling in the registration number.
## as for (a): partial credits should only be used for multiple-choice questions
## where at least one alternative is correct and at least one is false
## [note that in this example this is not the case for the first question
## (single-choice) and the third question for Jane Doe (no alternative correct)]
## as for (c): for Ambi Dexter such an error was included in the PNG example
## image, the actual number is "9911071" but the crosses indicate "9901071"
## clean up previous evaluation
file.remove(c("nops_eval.csv", "nops_eval.zip"))
## write correct registration information
write.table(data.frame(
registration = c("1501090", "9911071"),
name = c("Jane Doe", "Ambi Dexter"),
id = c("jane_doe", "ambi_dexter")
), file = "Exam-2015-07-29.csv", sep = ";", quote = FALSE, row.names = FALSE)
## call nops_eval() with modified options, where the error in the registration
## number of Ambi Dexter will trigger an interactive prompt
ev2 <- nops_eval(eval = exams_eval(partial = TRUE, rule = "false2"),
language = "de")
## inspect evaluated data
ev2
cbind(ev1$points, ev2$points)
## inspect corresponding HTML reports
unzip("nops_eval.zip")
browseURL(file.path(mydir, "jane_doe", "Exam-2015-07-29.html"))
browseURL(file.path(mydir, "ambi_dexter", "Exam-2015-07-29.html"))
}
## switch back to original working directory
setwd(odir)
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