QQ Plot — QQPlot • ggforge

QQ plot is a graphical tool to compare two distributions by plotting their quantiles against each other. Can also create PP (probability-probability) plots.

Usage

QQPlot(
  data,
  val,
  val_trans = NULL,
  type = c("qq", "pp"),
  band = NULL,
  line = list(),
  point = list(),
  fill_name = "Bands",
  band_alpha = 0.5,
  split_by = NULL,
  split_by_sep = "_",
  facet_by = NULL,
  facet_scales = "fixed",
  facet_nrow = NULL,
  facet_ncol = NULL,
  facet_byrow = TRUE,
  theme = "theme_ggforge",
  theme_args = list(),
  palette = "Spectral",
  palcolor = NULL,
  aspect.ratio = NULL,
  legend.position = waiver(),
  legend.direction = "vertical",
  title = NULL,
  subtitle = NULL,
  xlim = NULL,
  ylim = NULL,
  xlab = NULL,
  ylab = NULL,
  seed = 8525,
  combine = TRUE,
  nrow = NULL,
  ncol = NULL,
  byrow = TRUE,
  axes = NULL,
  axis_titles = NULL,
  guides = NULL,
  design = NULL,
  ...
)

Arguments

data: A data frame containing the data to plot
val: A character string of the column name for the values to plot. A numeric column is expected.
val_trans: A function to transform the values before plotting. Default is NULL, which means no transformation.
type: A character string to specify the type of plot. Default is "qq", which means QQ plot. Other option is "pp" for PP plot.
band: A list of arguments to pass to qqplotr::stat_qq_band() or qqplotr::stat_pp_band(), depending on the value of type. Default is NULL, which means no band. If an empty list or TRUE is provided, the default arguments will be used. Multiple bands can be added by providing a list of lists.
line: A list of arguments to pass to qqplotr::stat_qq_line() or qqplotr::stat_pp_line(), depending on the value of type. Default is list(), which means to add a line with default arguments. If NULL is provided, no line will be added.
point: A list of arguments to pass to qqplotr::stat_qq_point() or qqplotr::stat_pp_point(), depending on the value of type. Default is list(), which means to add points with default arguments. If NULL is provided, no points will be added (not recommended).
fill_name: A character string to name the legend of fill. Default is "Bands".
band_alpha: A numeric value to set the alpha of all bands. Default is 0.5. It is a shortcut for setting alpha of all bands. You can override it by setting alpha in band argument.
split_by: Column name(s) to split data into multiple plots
split_by_sep: Separator when concatenating multiple split_by columns
facet_by: Column name(s) for faceting the plot
facet_scales: Scales for facets: "fixed", "free", "free_x", "free_y"
facet_nrow: Number of rows in facet layout
facet_ncol: Number of columns in facet layout
facet_byrow: Fill facets by row (TRUE) or column (FALSE)
theme: Theme name (string) or theme function
theme_args: List of arguments passed to theme function
palette: Color palette name
palcolor: Custom colors for palette
aspect.ratio: Aspect ratio of plot panel
legend.position: Legend position: "none", "left", "right", "bottom", "top"
legend.direction: Legend direction: "horizontal" or "vertical"
title: Plot title
subtitle: Plot subtitle
xlim: A numeric vector of length 2 to set the x-axis limits.
ylim: A numeric vector of length 2 to set the y-axis limits.
xlab: X-axis label
ylab: Y-axis label
seed: Random seed for reproducibility
combine: Whether to combine split plots into one
nrow: Number of rows when combining plots
ncol: Number of columns when combining plots
byrow: Fill combined plots by row
axes: How to handle axes in combined plots ("keep", "collect", "collect_x", "collect_y")
axis_titles: How to handle axis titles in combined plots
guides: How to handle guides in combined plots ("collect", "keep", "auto")
design: Custom layout design for combined plots
...: Additional arguments passed to atomic plotting functions.

Value

A ggplot object or wrap_plots object or a list of ggplot objects

Examples

set.seed(8525)
data <- data.frame(norm = rnorm(100))

QQPlot(data, val = "norm", band = TRUE)

QQPlot(data, val = "norm", band = list(
  list(bandType = "ks", mapping = ggplot2::aes(fill = "KS"), alpha = 0.3),
  list(bandType = "ts", mapping = ggplot2::aes(fill = "TS")),
  list(bandType = "pointwise", mapping = ggplot2::aes(fill = "Normal")),
  list(bandType = "boot", mapping = ggplot2::aes(fill = "Bootstrap"))
), band_alpha = 0.6)


# \donttest{
data(airquality, package = "datasets")
di <- "exp" # exponential distribution
dp <- list(rate = 2) # exponential rate parameter
QQPlot(airquality,
  val = "Ozone",
  band = list(distribution = di, dparams = dp),
  line = list(distribution = di, dparams = dp),
  point = list(distribution = di, dparams = dp)
)


de <- TRUE # enabling the detrend option
QQPlot(airquality,
  val = "Ozone",
  band = list(distribution = di, dparams = dp, detrend = de),
  line = list(distribution = di, dparams = dp, detrend = de),
  point = list(distribution = di, dparams = dp, detrend = de)
)


QQPlot(data, val = "norm", type = "pp", band = TRUE)


dp <- list(mean = 2, sd = 2) # shifted and rescaled Normal parameters
QQPlot(data,
  val = "norm", type = "pp",
  band = list(dparams = dp),
  point = list(dparams = dp)
)


QQPlot(data,
  val = "norm", type = "pp", band = TRUE,
  line = list(ab = c(.2, .5))
)


di <- "exp"
dp <- list(rate = .022) # value is based on some empirical tests
de <- TRUE
QQPlot(airquality,
  val = "Ozone", type = "pp",
  band = list(distribution = di, detrend = de, dparams = dp),
  line = list(detrend = de),
  point = list(distribution = di, detrend = de, dparams = dp),
  ylim = c(-.5, .5)
)

# }