How to extract exercises names from a nest list of exams from r `exams`?-CodePudding

I created 8 exams using the r exams package (each with the corresponding *.rds file). Each exam has the same 8 items (in a different order). All exams' *.rds were merged into a single list. As follows:


exams_list <- list(`00001` = list(exercise1 = list(question = c("\\emph{(2 \\myPoints)}", 
"Q1"), questionlist = c("A1", "A2","A3", "A4", "A5"), solution = NULL, 
    solutionlist = NULL, metainfo = list(file = "stat1_en_descriptive_stat_34", 
        markup = "latex", type = "schoice", name = "stat1_en_descriptive_stat_34", 
        title = NULL, section = NULL, version = NULL, solution = c(FALSE, 
        FALSE, FALSE, TRUE, FALSE), clozetype = NULL, points = 2, 
        time = NULL, shuffle = 5, length = 5L, string = "stat1_en_descriptive_stat_34: b", 
        maxchars = NULL, abstention = NULL, stringtype = NULL, 
        seed = 40283L), supplements = structure(character(0), names = character(0), dir = "/tmp/RtmpH83QPG/file808555d833f/exam1/exercise1")), 
    exercise2 = list(question = c("\\emph{(2 \\myPoints)}", "Q2", 
    "", "\\hfill\\break", "\\includegraphics[width=0.55\\textwidth,height=\\textheight]{stat1_descriptive_stat_10.png}"
    ), questionlist = c("A1", "A2","A3", "A4", "A5"
    ), solution = NULL, solutionlist = NULL, metainfo = list(
        file = "stat1_en_descriptive_stat_10", markup = "latex", 
        type = "schoice", name = "stat1_en_descriptive_stat_10", 
        title = NULL, section = NULL, version = NULL, solution = c(FALSE, 
        TRUE, FALSE, FALSE, FALSE), clozetype = NULL, points = 2, 
        time = NULL, shuffle = 5, length = 5L, string = "stat1_en_descriptive_stat_10: b", 
        maxchars = NULL, abstention = NULL, stringtype = NULL, 
        seed = 23616L), supplements = structure(c(stat1_descriptive_stat_10.png = "/tmp/RtmpH83QPG/file808555d833f/exam1/exercise2/stat1_descriptive_stat_10.png"), dir = "/tmp/RtmpH83QPG/file808555d833f/exam1/exercise2")), 
    exercise3 = list(question = c("\\emph{(2 \\myPoints)}", "Q3"
    ), questionlist = c("A1", "A2","A3", "A4", "A5"),
    solution = NULL, solutionlist = NULL, metainfo = list(
        file = "stat1_en_descriptive_stat_15", markup = "latex", 
        type = "schoice", name = "stat1_en_descriptive_stat_15", 
        title = NULL, section = NULL, version = NULL, solution = c(FALSE, 
        FALSE, FALSE, TRUE, FALSE), clozetype = NULL, points = 2, 
        time = NULL, shuffle = 5, length = 5L, string = "stat1_en_descriptive_stat_15: d", 
        maxchars = NULL, abstention = NULL, stringtype = NULL, 
        seed = 84038L), supplements = structure(character(0), names = character(0), dir = "/tmp/RtmpH83QPG/file808555d833f/exam1/exercise3")), 
    exercise4 = list(question = c("\\emph{(2 \\myPoints)}", "Q4"), questionlist = c("A1", "A2","A3", "A4", "A5"), solution = NULL, solutionlist = NULL, 
        metainfo = list(file = "stat1_en_descriptive_stat_29", 
            markup = "latex", type = "schoice", name = "stat1_en_descriptive_stat_29", 
            title = NULL, section = NULL, version = NULL, solution = c(FALSE, 
            FALSE, FALSE, TRUE, FALSE), clozetype = NULL, points = 2, 
            time = NULL, shuffle = 5, length = 5L, string = "stat1_en_descriptive_stat_29: d", 
            maxchars = NULL, abstention = NULL, stringtype = NULL, 
            seed = 104204L), supplements = structure(character(0), names = character(0), dir = "/tmp/RtmpH83QPG/file808555d833f/exam1/exercise4")), 
    exercise5 = list(question = c("\\emph{(2 \\myPoints)}", "Q5"
    ), questionlist = c("A1", "A2","A3", "A4", "A5"), solution = NULL, 
        solutionlist = NULL, metainfo = list(file = "stat1_en_prob_8", 
            markup = "latex", type = "schoice", name = "stat1_en_prob_8", 
            title = NULL, section = NULL, version = NULL, solution = c(FALSE, 
            FALSE, TRUE, FALSE, FALSE), clozetype = NULL, points = 2, 
            time = NULL, shuffle = 5, length = 5L, string = "stat1_en_prob_8: c", 
            maxchars = NULL, abstention = NULL, stringtype = NULL, 
            seed = 99878L), supplements = structure(character(0), names = character(0), dir = "/tmp/RtmpH83QPG/file808555d833f/exam1/exercise5"))), 
    `00002` = list(exercise1 = list(question = c("\\emph{(2 \\myPoints)}", 
    "Q1"), questionlist = c("A1", "A2","A3", "A4", "A5"
    ), solution = NULL, solutionlist = NULL, metainfo = list(
        file = "stat1_en_descriptive_stat_10", markup = "latex", 
        type = "schoice", name = "stat1_en_descriptive_stat_10", 
        title = NULL, section = NULL, version = NULL, solution = c(FALSE, 
        FALSE, TRUE, FALSE, FALSE), clozetype = NULL, points = 2, 
        time = NULL, shuffle = 5, length = 5L, string = "stat1_en_descriptive_stat_10: c", 
        maxchars = NULL, abstention = NULL, stringtype = NULL, 
        seed = 66957L), supplements = structure(c(stat1_descriptive_stat_10.png = "/tmp/RtmpH83QPG/file8087677e29b/exam1/exercise1/stat1_descriptive_stat_10.png"), dir = "/tmp/RtmpH83QPG/file8087677e29b/exam1/exercise1")), 
        exercise2 = list(question = c("\\emph{(2 \\myPoints)}", 
        "Q2"), 
            questionlist = c("A1", "A2","A3", "A4", "A5"), solution = NULL, 
            solutionlist = NULL, metainfo = list(file = "stat1_en_descriptive_stat_34", 
                markup = "latex", type = "schoice", name = "stat1_en_descriptive_stat_34", 
                title = NULL, section = NULL, version = NULL, 
                solution = c(FALSE, FALSE, FALSE, TRUE, FALSE
                ), clozetype = NULL, points = 2, time = NULL, 
                shuffle = 5, length = 5L, string = "stat1_en_descriptive_stat_34: a", 
                maxchars = NULL, abstention = NULL, stringtype = NULL, 
                seed = 24446L), supplements = structure(character(0), names = character(0), dir = "/tmp/RtmpH83QPG/file8087677e29b/exam1/exercise2")), 
        exercise3 = list(question = c("\\emph{(2 \\myPoints)}", 
        "Q3"), questionlist = c("A1", "A2","A3", "A4", "A5"), solution = NULL, solutionlist = NULL, 
            metainfo = list(file = "stat1_en_descriptive_stat_29", 
                markup = "latex", type = "schoice", name = "stat1_en_descriptive_stat_29", 
                title = NULL, section = NULL, version = NULL, 
                solution = c(FALSE, FALSE, TRUE, FALSE, FALSE
                ), clozetype = NULL, points = 2, time = NULL, 
                shuffle = 5, length = 5L, string = "stat1_en_descriptive_stat_29: c", 
                maxchars = NULL, abstention = NULL, stringtype = NULL, 
                seed = 42982L), supplements = structure(character(0), names = character(0), dir = "/tmp/RtmpH83QPG/file8087677e29b/exam1/exercise3")), 
        exercise4 = list(question = c("\\emph{(4 \\myPoints)}", 
        "Q4"
        ), questionlist = c("A1", "A2","A3", "A4", "A5"), solution = NULL, 
            solutionlist = NULL, metainfo = list(file = "stat1_en_prob_8", 
                markup = "latex", type = "schoice", name = "stat1_en_prob_8", 
                title = NULL, section = NULL, version = NULL, 
                solution = c(FALSE, TRUE, FALSE, FALSE, FALSE
                ), clozetype = NULL, points = 4, time = NULL, 
                shuffle = 5, length = 5L, string = "stat1_en_prob_8: b", 
                maxchars = NULL, abstention = NULL, stringtype = NULL, 
                seed = 80660L), supplements = structure(c(stat1_en_descriptive_stat_20_1.png = "/tmp/RtmpH83QPG/file8087677e29b/exam1/exercise4/stat1_en_prob_8_1.png", 
            stat1_en_descriptive_stat_20_2.png = "/tmp/RtmpH83QPG/file8087677e29b/exam1/exercise4/stat1_en_prob_8_2.png"
            ), dir = "/tmp/RtmpH83QPG/file8087677e29b/exam1/exercise4")), 
        exercise5 = list(question = c("\\emph{(2 \\myPoints)}", 
        "Q5"
        ), questionlist = c("A1", "A2","A3", "A4", "A5"
        ), solution = NULL, solutionlist = NULL, metainfo = list(
            file = "stat1_en_descriptive_stat_15", markup = "latex", 
            type = "schoice", name = "stat1_en_descriptive_stat_15", 
            title = NULL, section = NULL, version = NULL, solution = c(FALSE, 
            TRUE, FALSE, FALSE, FALSE), clozetype = NULL, points = 2, 
            time = NULL, shuffle = 5, length = 5L, string = "stat1_en_descriptive_stat_15: b", 
            maxchars = NULL, abstention = NULL, stringtype = NULL, 
            seed = 69316L), supplements = structure(character(0), names = character(0), dir = "/tmp/RtmpH83QPG/file8087677e29b/exam1/exercise5"))))

I want to make a psychometric analysis of each of the items (per exam). As such, I want to extract the names of the exercises per exam, and use them to merge the answers to all the items adequately.

For the first step I need to extract the information from this list as follows:

exams_list$`00001`$exercise1$metainfo$name
exams_list$`00001`$exercise2$metainfo$name
#...
exams_list$`00002`$exercise1$metainfo$name
exams_list$`00002`$exercise2$metainfo$name

I tried to use the purrr package but I was not successful. My goal is to end up with list of vectors; one vector per exame containing the names of the exercises.

CodePudding user response：

You can use a nested for() loop or nested sapply() for this:

sapply(exams_list, function(x) sapply(x, function(y) y$metainfo$name))
##           00001                          00002                         
## exercise1 "stat1_en_descriptive_stat_34" "stat1_en_descriptive_stat_10"
## exercise2 "stat1_en_descriptive_stat_10" "stat1_en_descriptive_stat_34"
## exercise3 "stat1_en_descriptive_stat_15" "stat1_en_descriptive_stat_29"
## exercise4 "stat1_en_descriptive_stat_29" "stat1_en_prob_8"             
## exercise5 "stat1_en_prob_8"              "stat1_en_descriptive_stat_15"

The outer loop/apply is over the random replications (here 2), yielding the columns of the output. And the inner loop/apply is over the exercises in each replication (here 5), yielding the rows of the output.

From the matrix above you can obtain the necessary permutation to a desired order of the exercises, e.g., via match().

For the psychometric analysis I typically use the following workflow (using our own psychotools package).

## read nops evaluation output
x <- read.csv2("nops_eval.csv", dec = ".")

## select check columns and set 'not answered' to 'incorrect'
x <- as.matrix(x[, grep("^check\\.", names(x))])
x[is.na(x)] <- 0

## here you would have to apply the permutation and set nice colnames

## declare item-response matrix with itemresp class in psychotools
library("psychotools")
x <- itemresp(x)
plot(x)

## fit basic Rasch model (via CML) and person-item map
m <- raschmodel(x)
piplot(m)

Stacked bar plot of raw frequencies	Person-item map for Rasch model

For more refined analyses you might also be interested in these presentations:

Examining Exams with the psycho* Family of R Packages, Psychoco 2015
Examining Exams Using Rasch Models and Assessment of Measurement Invariance, WU Wien 2016