quantileLines: Add quantile lines to a paired scatterplot

In frankhezemans/fhTools: Personal 'R' package of Frank Hezemans

Description

quantileLines Adds line segments at the requested quantiles of the x and y variables. This is a useful addition to a paired scatterplot, to illustrate how observations are linked between conditions. The quantile lines are set as the lowest layer, so they won't obscure the original paired scatterplot. Adapted from the plot_quartile_bars function in the rogme package.

Usage

quantileLines(p, probs = c(0.25, 0.5, 0.75), colour_m = "darkgrey",
  colour = "grey", size_m = 0.5, size = 0.25, linetype_m = "dashed",
  linetype = "dashed")

Arguments

p	the ggplot object to which the quantile lines should be added.
probs	numeric vector of probabilities with values in [0,1].
colour_m	character indicating the colour of the middle line.
colour	character indicating the colour of the other lines.
size_m	numeric indicating the thickness of the middle line.
size	numeric indicating the thickness of the other lines.
linetype_m	character indicating the linetype of the middle line.
linetype	character indicating the linetype of the other lines.

Details

In order for these quantile lines to make sense, the axes of the plot should be identically scaled.

Author(s)

Frank H. Hezemans, [e-mail]

See Also

quantile, geom_segment

Examples

library(ggplot2)
library(UsingR) # Package contains dataset

# Get data
data <- crime

# Create paired scatterplot
paired_scatter <- ggplot(data = data, aes(x = y1983, y = y1993)) +
    geom_abline(slope = 1, intercept = 0) +
    geom_point(shape = 21, fill = "grey") +
    xlim(0, 1500) + ylim(0, 1500) +
    labs(title = "Violent crime in 50 U.S. states in 1983 and 1993",
         subtitle = "Rates per 100,000 population",
         x = "Violent crime rate in 1983",
         y = "Violent crime rate in 1993") +
    theme_minimal() +
    theme(aspect.ratio = 1)

# Add lines at the first quartile, median, and third quartile
paired_scatter <- quantileLines(paired_scatter, probs = c(0.25, 0.5, 0.75),
                                colour_m = "black", colour = "grey",
                                size_m = 0.5, size = 0.25,
                                linetype_m = "longdash", linetype = "dashed")          

frankhezemans/fhTools documentation built on May 7, 2019, 3:14 p.m.