Function to create stacked bar graph of a set of variables with the same categorical scale (e.g., survey responses in a question set)

CreateMCGraph.R

# Get ranking graph for multiple choice
getmcgraph <- function(t, levels, items, sortby) {
  t <- lapply(t, function(x) factor(x, levels=levels))
  end <- data.frame(matrix(NA, nrow=1, ncol=length(levels)))
  names(end) <- levels
  for(i in 1:length(t)) {
    end <- rbind(end, round(100*prop.table(table(t[i])), digits=2))
  }
  end <- end[-1,]
  end <- cbind(items, end)
  names(end)[1] <- "Item"
  end <- end[order(end[sortby]),]
  itemorder <- as.character(end[["Item"]])
  library(reshape)
  coldata <- melt(end, id="Item")
  coldata$Item <- wrap_strings(as.character(coldata$Item), 30)
  coldata$Item <- factor(coldata$Item, levels=wrap_strings(itemorder, 30), ordered=TRUE)
  return(ggplot(coldata, aes(x=factor(Item), y=value, fill=factor(variable))) + 
    geom_bar(stat="identity") +
    xlab("") +
    ylab("Percent") +
    coord_flip() + 
    theme +
    scale_fill_discrete(name="Response"))
}