Dumbell plot

dumbellplot

dat <- data.frame(
    freq = c(37, 88, 47, 89, 28, 68, 65, 98, 68, 86, 50, 87, 59, 82, 45, 65, 52, 32, 59, 47, 68, 78, 39, 31, 64, 68)
)

dat[["sector"]] <- rep(c("U.S. adults", "AAAS scientist"), nrow(dat)/2)

field <- c("Biomedical sciences", "Climate, energy, space sciences")
dat[["field"]] <- factor(rep(field, c(10, 16)), levels=field)

items <-  c(
    "Safe to eat genetically\nmodified foods", 
    "Favor the use of animas\nin research", 
    "Safe to eat foods grown\nwith pesticides",  
    "Humans have evolved over\ntime",  
    "Childhood vaccines such\nas MMR should be required  ",  
    "Climate change is mostly\ndue to human activity",  
    "Growing world population\nwill be a major problem",  
    "Favor building more\nnuclear power plants",  
    "Favor more offshore\ndrilling",  
    "Astronaughts essential for\nfuture of U.S. space program",  
    "Favor increased use of\nbioengineered fuel",
    "Favor increased use of\nfracking",  
    "Space station has been\na good investment for U.S."
)


dat[["Item"]] <- factor(rep(items, each=2), levels=rev(items))

library(dplyr)

diffs <- dat %>%
    group_by(Item, field) %>%
    summarise(
        diff = abs(diff(freq)),
        mid = mean(freq),
        xmin = min(freq),
        xmax=max(freq)
    )


ext <- rep("", nrow(diffs))
ext[c(5, 13)] <- "point gap"

ext2 <- rep("", nrow(diffs))
ext2[c(5, 13)] <- "%"

#amt <- 2
amt <- 1.5

library(ggplot2)

ggplot(dat, aes(y = Item, x=freq)) +
    geom_segment(data=diffs, aes(x=xmin, xend=xmax, y=Item, yend=Item), color="royalblue2", size=5.5) +
    geom_point(color = "navy", size=5.5) +
    geom_point(shape=21, color = "navy", size=4.8, aes(fill=sector)) +
    facet_grid(field~., space="free", scales="free") +
    scale_fill_manual(values = c("white", "darkblue"), guide=FALSE) +
    theme_bw() +
    coord_cartesian(xlim = c(24, 102)) +
    ylab(NULL) + xlab(NULL) +
    geom_text(data = diffs, color = "white", 
        aes(label = paste(diff, ext), x=mid, y=Item), 
        size=3, vjust = .4, hjust=.2) +
    geom_text(data = diffs, color = "grey60", aes(label = paste0(xmin, ext2), x=xmin -amt, y=Item), 
        size=3, vjust = .4, hjust=1) +     
    geom_text(data = diffs, color = "grey60", aes(label = paste0(xmax, ext2), x=xmax + amt, y=Item), 
        size=3, vjust = .4, hjust=0)   +
    theme(
        axis.text.y = element_text(hjust=0),
        axis.text.x = element_blank(),
        axis.ticks = element_blank(),
        panel.grid.minor.x = element_blank(),
        panel.grid.major.x = element_blank(),
        panel.grid.major.y = element_blank(),
        panel.border = element_blank(),
        strip.background = element_rect(color=NA, fill="grey75"),
        strip.text.y = element_text(size=12, face="bold", hjust=.05),
        panel.spacing = unit(1, "lines")
    ) + 
    geom_hline(color="grey60", linetype="dotted", size=.7, yintercept=seq(.5, to=8.5, by=1))