adding stat_joy, Lincoln weather data, start for a vignette

DESCRIPTION

@@ -19,6 +19,7 @@ Suggests:
     knitr
 VignetteBuilder: knitr
 Collate:
+    'data.R'
     'ggjoy.R'
     'geoms.R'
     'stats.R'

R/data.R

@@ -0,0 +1,14 @@
+#' Weather in Lincoln, Nebraska in 2016.
+#'
+#' A dataset containing weather information from Lincoln, Nebraska, from 2016.
+#' Originally downloaded from Weather Underground by Austin Wehrwein, http://austinwehrwein.com/.
+#' The variables are as follows:
+#'
+#' @format A tibble with 366 rows and 24 variables:
+#' \describe{
+#'   \item{CST}{Day of the measurement}
+#'   \item{Max Temperature [F]}{Maximum temperature in Fahrenheit}
+#'   \item{Mean Temperature [F]}{Maximum temperature in Fahrenheit}
+#'   \item{Month}{The month in which the measurement was taken}
+#' }
+"lincoln_weather"

R/stats.R

@@ -0,0 +1,61 @@
+# Code for stat_joy based on stat_density_common in the "extending ggplot2" vignette
+
+#' Stat for density joyplots
+#'
+#' This stat is the default stat used by \code{geom_joy}. It is very similar to \code{stat_density},
+#' however there are a few differences. Most importantly, the density bandwidth is chosen across
+#' the entire dataset.
+#'
+#' @importFrom ggplot2 layer
+#' @export
+stat_joy <- function(mapping = NULL, data = NULL, geom = "joy",
+                     position = "identity", na.rm = TRUE, show.legend = NA,
+                     inherit.aes = TRUE, bandwidth = NULL, ...)
+{
+  layer(
+    stat = StatJoy,
+    data = data,
+    mapping = mapping,
+    geom = geom,
+    position = position,
+    show.legend = show.legend,
+    inherit.aes = inherit.aes,
+    params = list(bandwidth = bandwidth, na.rm = na.rm, ...)
+  )
+}
+
+
+#' @importFrom ggplot2 ggproto Stat
+#' @export
+StatJoy <- ggproto("StatJoy", Stat,
+  required_aes = "x",
+  default_aes = aes(height = ..density..),
+
+  setup_params = function(data, params) {
+    if (is.null(params$bandwidth)) {
+      xdata <- na.omit(data.frame(x=data$x, group=data$group))
+      xs <- split(xdata$x, xdata$group)
+      bws <- vapply(xs, bw.nrd0, numeric(1))
+      bw <- mean(bws, na.rm = TRUE)
+      message("Picking joint bandwidth of ", signif(bw, 3))
+
+      params$bandwidth <- bw
+    }
+
+    min <- min(data$x, na.rm=TRUE) - 3 * params$bandwidth
+    max <- max(data$x, na.rm=TRUE) + 3 * params$bandwidth
+
+    list(
+      bandwidth = params$bandwidth,
+      min = min,
+      max = max,
+      #na.rm = params$na.rm
+      na.rm = TRUE
+    )
+  },
+
+  compute_group = function(data, scales, min, max, bandwidth = 1, na.rm = TRUE) {
+    d <- density(data$x, bw = bandwidth, from = min, to = max, na.rm)
+    data.frame(x = d$x, density = d$y)
+  }
+)

data-raw/lincoln-weather.R

@@ -0,0 +1,7 @@
+require(readr)
+
+lincoln_weather <- read_csv("data-raw/lincoln-weather.csv")
+lincoln_weather$Month<-months(as.Date(lincoln_weather$CST))
+lincoln_weather$Month<-factor(lincoln_weather$Month, levels=rev(unique(lincoln_weather$Month)))
+
+devtools::use_data(lincoln_weather, overwrite = TRUE)

vignettes/introduction.Rmd

@@ -0,0 +1,44 @@
+---
+title: "Introduction to ggjoy"
+author: "Claus O. Wilke"
+date: "`r Sys.Date()`"
+output:
+  rmarkdown::html_vignette:
+    fig_width: 5
+vignette: >
+  %\VignetteIndexEntry{Introduction to ggjoy}
+  %\VignetteEngine{knitr::rmarkdown}
+  %\usepackage[utf8]{inputenc}
+---
+
+Basic usage:
+```{r}
+library(ggplot2)
+library(ggjoy)
+
+ggplot(iris, aes(x=Sepal.Length, y=Species, group=Species)) + geom_joy()
+```
+
+
+## Gallery of examples
+
+Temperatures in Lincoln, Nebraska. Modified from a [blog post](http://austinwehrwein.com/data-visualization/it-brings-me-ggjoy/) by Austin Wehrwein.
+```{r message=FALSE, fig.width = 7.5, fig.height = 5}
+ggplot(lincoln_weather, aes(x = `Mean Temperature [F]`, y = `Month`)) +
+  geom_joy(scale = 3, rel_min_height = 0.01) +
+  scale_x_continuous(expand = c(0.01, 0)) +
+  scale_y_discrete(expand = c(0.01, 0)) +
+  labs(title = 'Temperatures in Lincoln NE',
+       subtitle = 'Mean temperatures (Fahrenheit) by month for 2016\nData: Original CSV from the Weather Underground') +
+  theme_joy(font_size = 13, grid = T) + theme(axis.title.y = element_blank())
+```
+
+Evolution of movie lengths over time. Data from the IMDB, as provided in the ggplot2movies package.
+```{r message=TRUE, fig.width = 5, fig.height = 6}
+library(ggplot2movies)
+ggplot(movies[movies$year>1912,], aes(x=length, y=year, group=year)) +
+  geom_joy(scale=10, size=0.25, rel_min_height=0.03) +
+  theme_joy() +
+  scale_x_continuous(limits=c(1, 200), expand=c(0.01, 0)) +
+  scale_y_reverse(breaks=c(2000, 1980, 1960, 1940, 1920, 1900), expand=c(0.01, 0))
+```