Multiplot Layout

The multiplot function allows for multiple visualizations to be added into a single image. The multiplot function for ggplot2 was taken from the Winston Chang. (2017). Cookbook for R. http://www.cookbook-r.com/.

multiplot <- function(..., plotlist=NULL, file, cols=1, layout=NULL) {
  # Make a list from the ... arguments and plotlist
  plots <- c(list(...), plotlist)
  
  numPlots = length(plots)
  
  # If layout is NULL, then use 'cols' to determine layout
  if (is.null(layout)) {
    # Make the  panel
    # ncol: Number of columns of plots
    # nrow: Number of rows needed, calculated from # of cols
    layout <- matrix(seq(1, cols * ceiling(numPlots/cols)),
                     ncol = cols, nrow = ceiling(numPlots/cols))
  }

  if (numPlots==1) {
    print(plots[[1]])
    
  } else {
    # Set up the page
    grid.newpage()
    pushViewport(viewport(layout = grid.layout(nrow(layout), ncol(layout))))
    
    # Make each plot, in the correct location
    for (i in 1:numPlots) {
      # Get the i,j matrix positions of the regions that contain this subplot
      matchidx <- as.data.frame(which(layout == i, arr.ind = TRUE))
      
      print(plots[[i]], vp = viewport(layout.pos.row = matchidx$row,
                                      layout.pos.col = matchidx$col))
    }
  }
}

Setting up visualization themes and parameters

Before visualizing the results, themes for the visualization are set for the ggplot2 package. A set of color palettes are added as well.

#Theme for ggplot2
theme_set(theme_light())

##Color Scales and setting for graphs
strip <- c("#DCDCDC") #Grey

#Univariate color scale
#Multi-color univariate color palette for the module type variables
#Dark blue to yellow green
pal1 <- function (n, h = c(360, 45), c. = c(17, 100), l = c(2, 76), 
                  power = c(2.53333333333333, 1.6), fixup = TRUE, gamma = NULL, 
                  alpha = 1, ...) 
                  {
                    if (!is.null(gamma)) 
                      warning("'gamma' is deprecated and has no effect")
                    if (n < 1L) 
                      return(character(0L))
                    h <- rep(h, length.out = 2L)
                    c <- rep(c., length.out = 2L)
                    l <- rep(l, length.out = 2L)
                    power <- rep(power, length.out = 2L)
                    rval <- seq(1, 0, length = n)
                    rval <- hex(polarLUV(L = l[2L] - diff(l) * rval^power[2L], 
                                         C = c[2L] - diff(c) * rval^power[1L], H = h[2L] - diff(h) * 
                                           rval), fixup = fixup, ...)
                    if (!missing(alpha)) {
                      alpha <- pmax(pmin(alpha, 1), 0)
                      alpha <- format(as.hexmode(round(alpha * 255 + 0.0001)), 
                                      width = 2L, upper.case = TRUE)
                      rval <- paste(rval, alpha, sep = "")
                    }
                    return(rval)
                  }

#Color Scales for Module Types
modColors <- pal1(4)
modColors <- modColors[c(2,1,3,4)]

Figure Labels

##Label groups
#Certification Groups
userGrps <- as_labeller(c('unq_stu_per' = paste0("All students (", length(students$user_id)," students)"),
                           'unq_stu_per.1'  = paste0("Certificate granted, grades between 100%-70% (",
                                                     length(students[students$grade>=.7,]$user_id)," students)"),  
                           'unq_stu_per.2'  = paste0("No certification but active, with grades less than 70% (",
                                                     length(students[students$grade<.7,]$user_id)," students)")))
userGrps2 <- as_labeller(c('unq_stu_per' = paste0("All students\n(", length(students$user_id)," students)"),
                          'unq_stu_per.1'  = paste0("Certificate granted\n(",
                                                    length(students[students$grade>=.7,]$user_id)," students)"),  
                          'unq_stu_per.2'  = paste0("No certification active\n(",
                                                    length(students[students$grade<.7,]$user_id)," students)")))
modType <- as_labeller(c("html+block" = "HTML/Text\nModule",
                         "openassessment+block" = "Open Assessment\nModule",
                         "problem+block" = "Problem\nModule",
                         "video+block"  = "Video\nModule"))
modLed <- c("HTML/Text\nModule", "Open Assessment\nModule", "Problem\nModule","Video\nModule")

Set vertical lines found in figure

vline <- as.data.frame(unique(mod_unq$L1))
names(vline)[1] <- "L1"
vline$mod <- NA
for(i in 1:nrow(vline)){
  vline[i,]$mod <- max(mod_unq[mod_unq$L1==vline[i,1],]$order)
}

Fig 5A Mean Number of Events per Html/Text Module

p1 <- ggplot(mod_event[mod_event$module.type=="html+block",], aes(x=order,y=val2)) +
        geom_vline(xintercept=vline[1:nrow(vline)-1,2],linetype="dashed") +
        geom_point(aes(colour=module.type, size=val1)) +
        scale_size(range = c(0, 2.5)) +
        scale_colour_manual(values=modColors[1]) +
        labs(y="Mean Interaction Events per Student") +
        theme(plot.title = element_text(hjust = 0),
              legend.position="none", 
              strip.background = element_rect(fill=strip),
              strip.text=element_text(color = "Black"),
              axis.title.x = element_blank()) +
        facet_wrap( ~ var1, nrow=4, strip.position="right", labeller =userGrps2)
p1 + xlab("Course Module Sequence")

Fig 5B Mean Number of Events per Video Module

p2 <- ggplot(mod_event[mod_event$module.type=="video+block",], aes(x=order,y=val2)) +
        geom_vline(xintercept=vline[1:nrow(vline)-1,2],linetype="dashed") +
        geom_point(aes(colour=module.type, size=val1)) +
        scale_size(range = c(0, 2.5)) +
        scale_colour_manual(values=modColors[4]) +
        theme(plot.title = element_text(hjust = 0),
              legend.position="none", 
              strip.background = element_rect(fill=strip),
              strip.text=element_text(color = "Black"),
              axis.title = element_blank()) +
        facet_wrap( ~ var1, nrow=4, strip.position="right", labeller =userGrps2)
p2 + labs(x="Course Module Sequence", 
             y="Mean Interaction Events per Student")

Fig 5C Mean Number of Events per Problem Module

p3 <- ggplot(mod_event[mod_event$module.type=="problem+block",], aes(x=order,y=val2)) +
        geom_vline(xintercept=vline[1:nrow(vline)-1,2],linetype="dashed") +
        geom_point(aes(colour=module.type, size=val1)) +
        scale_size(range = c(0, 2.5)) +
        scale_colour_manual(values=modColors[3]) +
        labs(x="Course Module Sequence", 
             y="Mean Interaction Events per Student")+
        theme(plot.title = element_text(hjust = 0),
             legend.position="none", 
             strip.background = element_rect(fill=strip),
             strip.text=element_text(color = "Black")) +
        facet_wrap( ~ var1, nrow=4, strip.position="right", labeller =userGrps2)
p3

Fig 5D Mean Number of Events per Open Assessment Module

p4 <- ggplot(mod_event[mod_event$module.type=="openassessment+block",], aes(x=order,y=val2)) +
        geom_vline(xintercept=vline[1:nrow(vline)-1,2],linetype="dashed") +
        geom_point(aes(colour=module.type, size=val1)) +
        scale_size(range = c(0, 2.5)) +
        scale_colour_manual(values=modColors[2]) +
        labs(x="Course Module Sequence") +
        theme(plot.title = element_text(hjust = 0),
              legend.position="none", 
              strip.background = element_rect(fill=strip),
              strip.text=element_text(color = "Black"),
              axis.title.y = element_blank()) +
        facet_wrap( ~ var1, nrow=4, strip.position="right", labeller =userGrps2)
p4 + ylab("Mean Interaction Events per Student")

Fig 5 Composite

#Final Layout
multiplot(p1 + ggtitle("A")+ theme(plot.title = element_text(hjust = 0)),
          p3 + ggtitle("B")+ theme(plot.title = element_text(hjust = 0)),
          p2 + ggtitle("C")+ theme(plot.title = element_text(hjust = 0)),
          p4 + ggtitle("D")+ theme(plot.title = element_text(hjust = 0)),cols=2)