How can we make xkcd style graphs?

You might want to consider the following package:

Package xkcd: Plotting ggplot2 graphics in a XKCD style.

library(xkcd)
vignette("xkcd-intro")

Some examples (Scatterplots, Bar Charts):

Scatterplot:

https://i.stack.imgur.com/IWMKd.png

Bar Chart:

https://i.stack.imgur.com/LyEvh.png

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Thinking along the same line as some of the other answers, I've "un-ggplotted" the chart and also added on the flexibility of the x-axis label locations (which seems to be common in xkcd) and an arbitrary label on the chart.

Note that I had a few issues with loading the Humor Sans font and manually downloaded it to working directory.

https://i.stack.imgur.com/uMUym.jpg

And the code...

library(ggplot2)
library(extrafont)

### Already have read in fonts (see previous answer on how to do this)
loadfonts()

### Set up the trial dataset 
data <- NULL
data$x <- seq(1, 10, 0.1)
data$y1 <- sin(data$x)
data$y2 <- cos(data$x)
data$xaxis <- -1.5

data <- as.data.frame(data)

### XKCD theme
theme_xkcd <- theme(
    panel.background = element_rect(fill="white"), 
    axis.ticks = element_line(colour=NA),
    panel.grid = element_line(colour="white"),
    axis.text.y = element_text(colour=NA), 
    axis.text.x = element_text(colour="black"),
    text = element_text(size=16, family="Humor Sans")
    )

 ### Plot the chart
 p <- ggplot(data=data, aes(x=x, y=y1))+
      geom_line(aes(y=y2), position="jitter")+
      geom_line(colour="white", size=3, position="jitter")+
      geom_line(colour="red", size=1, position="jitter")+
      geom_text(family="Humor Sans", x=6, y=-1.2, label="A SIN AND COS CURVE")+
      geom_line(aes(y=xaxis), position = position_jitter(h = 0.005), colour="black")+
      scale_x_continuous(breaks=c(2, 5, 6, 9), 
      labels = c("YARD", "STEPS", "DOOR", "INSIDE"))+labs(x="", y="")+
      theme_xkcd

ggsave("xkcd_ggplot.jpg", plot=p, width=8, height=5)

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Basic line-drawing function:

xkcd_line <- function(x, y, color) {
  len <- length(x);
  rg <- par("usr");
  yjitter <- (rg[4] - rg[3]) / 1000;
  xjitter <- (rg[2] - rg[1]) / 1000;
  x_mod <- x + rnorm(len) * xjitter;
  y_mod <- y + rnorm(len) * yjitter;
  lines(x_mod, y_mod, col='white', lwd=10);
  lines(x_mod, y_mod, col=color, lwd=5);
}

Basic axis:

xkcd_axis <- function() {
  rg <- par("usr");
  yaxis <- 1:100 / 100 * (rg[4] - rg[3]) + rg[3];
  xaxis <- 1:100 / 100 * (rg[2] - rg[1]) + rg[1];
  xkcd_line(1:100 * 0 + rg[1] + (rg[2]-rg[1])/100, yaxis,'black')
  xkcd_line(xaxis, 1:100 * 0 + rg[3] + (rg[4]-rg[3])/100, 'black')
}

And sample code:

data <- data.frame(x=1:100)
data$one <- exp(-((data$x - 50)/10)^2)
data$two <- sin(data$x/10)
plot.new()
plot.window(
    c(min(data$x),max(data$x)),
    c(min(c(data$one,data$two)),max(c(data$one,data$two))))
xkcd_axis()
xkcd_line(data$x, data$one, 'red')
xkcd_line(data$x, data$two, 'blue')

Produces:

https://i.stack.imgur.com/Bx2Mm.png

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Here's an attempt at the fonts, based on links from the xkcd forums and the extrafont package:

As noted above there is a forum discussion about fonts on the xkcd site: I grabbed the first one I could find, there may be other (better?) options (@jebyrnes posts another source for possible fonts in comments above -- the TTF file is here; someone reported a 404 error for that source, you might alternatively try here or here, substituting those URLs appropriately for xkcdFontURL below; you may have to work a bit harder to retrieve the Github-posted links)

   xkcdFontURL <- "http://simonsoftware.se/other/xkcd.ttf"
   download.file(xkcdFontURL,dest="xkcd.ttf",mode="wb")

(This is for quickie, one-off use: for regular use you should put it in some standard system font directory.)

   library(extrafont)

The most useful information about fonts was on the extrafont github site -- this is taken from there

font_import(".")   ## because we downloaded to working directory
loadfonts()

Example taken more or less verbatim from the github site:

library(ggplot2)
p <- ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() +
  ggtitle("Fuel Efficiency of 32 Cars") +
  xlab("Weight (x1000 lb)") + ylab("Miles per Gallon") +
  theme(text=element_text(size=16, family="xkcd"))

ggsave("xkcd_ggplot.pdf", plot=p,  width=4, height=4)
## needed for Windows:
##   Sys.setenv(R_GSCMD = "C:/Program Files/gs/gs9.05/bin/gswin32c.exe")
embed_fonts("xkcd_ggplot.pdf")

https://i.stack.imgur.com/7ui0L.png

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I designed a xkcd themed analytics calendar just using RStudio. Here is an example of bar plot xkcd style

Font used = HumorSans.ttf [link given above]

Package used [xkcd]

https://i.stack.imgur.com/GkL19.jpg

Here is the code used

#using packages xkcd, ggplot 
library(xkcd)
library(ggplot2)
font_import(pattern="[H/h]umor")
loadfonts()

### Set up the trial dataset 
d1 <- data.frame('type'=c('DROWNING','RADIATION','TOILET',"ELECTRICAL",'NOISE','PANTRY','YOUR    FALLING ON OBJECTS','OBJECTS FALLING ON YOU','BOSS','FIRE','TRAVEL TO WORK'),'score'=c(2,2,3,6,6,6,11,14,21,26,30))

# we will keep adding layers on plot p. first the bar plot
p <- NULL
p <- ggplot() + xkcdrect(aes(xmin = type-0.1,xmax= type+0.1,ymin=0,ymax =score),
                     d1,fill= "#D55E00", colour= "#D55E00")  +
     geom_text(data=d1,aes(x=type,y=score+2.5,label=score,ymax=0),family="Humor Sans") +   coord_flip()

#hand drawn axes
d1long <- NULL
d1long <- rbind(c(0,-2),d1,c(12,32))
d1long$xaxis <- -1
d1long$yaxis <- 11.75

# drawing jagged axes
p <- p + geom_line(data=d1long,aes(x=type,y=jitter(xaxis)),size=1)
p <- p + geom_line(data=d1long,aes(x=yaxis,y=score), size=1) 

# draw axis ticks and labels
p <- p +  scale_x_continuous(breaks=seq(1,11,by=1),labels = data$Type) +
     scale_y_continuous(breaks=NULL)

#writing stuff on the graph
t1 <- "GOOGLE RESULTS"
p <- p + annotate('text',family="Humor Sans", x=12.5, y=12, label=t1, size=6) 

# XKCD theme
p <- p + theme(panel.background = element_rect(fill="white"),
           panel.grid = element_line(colour="white"),axis.text.x = element_blank(), 
           axis.text.y = element_text(colour="black"),text = element_text(size=18, family="Humor   Sans") ,panel.grid.major = element_blank(),panel.grid.minor = element_blank(),panel.border = element_blank(),axis.title.y = element_blank(),axis.title.x = element_blank(),axis.ticks = element_blank())

print(p)

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This is a very, very rough start and only covers (partially) the hand-drawn look and feel of the lines. It would take a little bit of work to automate this but adding some AR(1) noise to the response function could make it seem slightly hand drawn

set.seed(551)
x <- seq(0, 1, length.out = 1000)
y <- sin(x)

imperfect <- arima.sim(n = length(y), model = list(ar = c(.9999)))
imperfect <- scale(imperfect)
z <- y + imperfect*.005
plot(x, z, type = "l", col = "blue", lwd = 2)

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Here is my take on the lines with ggplot2 using some of the code from above:

ggplot()+geom_line(aes(x=seq(0,1,length.out=1000),y=sin(x)),position=position_jitter(width=0.02),lwd=1.5,col="white")+
  geom_line(aes(x=seq(0,1,length.out=1000),y=sin(x)),position=position_jitter(width=0.004),lwd=1.4,col="red")+
  geom_line(aes(x=seq(0,1,length.out=1000),y=cos(x)),position=position_jitter(width=0.02),lwd=1.5,col="white")+
  geom_line(aes(x=seq(0,1,length.out=1000),y=cos(x)),position=position_jitter(width=0.004),lwd=1.4,col="blue")+
  theme_bw()+theme(panel.grid.major=element_blank(),panel.grid.minor=element_blank())

Not sure how to replace the axes, but could use the same approach with jitter. Then it's a matter of importing the font from XKCD and layering with geom_text.

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