newggslopegraph: Plot a Slopegraph a la Tufte using dplyr and ggplot2

Description

Creates a "slopegraph" as conceptualized by Edward Tufte. Slopegraphs are minimalist and efficient presentations of your data that can simultaneously convey the relative rankings, the actual numeric values, and the changes and directionality of the data over time. Takes a dataframe as input, with three named columns being used to draw the plot. Makes the required adjustments to the ggplot2 parameters and returns the plot.

Usage

newggslopegraph(dataframe, Times, Measurement, Grouping,
  Title = "No title given", SubTitle = "No subtitle given",
  Caption = "No caption given", XTextSize = 12, YTextSize = 3,
  TitleTextSize = 14, SubTitleTextSize = 10, CaptionTextSize = 8,
  LineThickness = 1, LineColor = "ByGroup", DataTextSize = 2.5,
  WiderLabels = FALSE, RemoveMissing = TRUE)

Arguments

dataframe

a dataframe or an object that can be coerced to a dataframe. Basic error checking is performed, to include ensuring that the named columns exist in the dataframe. See the newcancer dataset for an example of how the dataframe should be organized.

Times

a column inside the dataframe that will be plotted on the x axis. Traditionally this is some measure of time. The function accepts a column of class ordered, factor or character. NOTE if your variable is currently a "date" class you must convert before using the function with as.character(variablename).

Measurement

a column inside the dataframe that will be plotted on the y axis. Traditionally this is some measure such as a percentage. Currently the function accepts a column of type integer or numeric. The slopegraph will be most effective when the measurements are not too disparate.

Grouping

a column inside the dataframe that will be used to group and distinguish measurements.

Title

Optionally the title to be displayed. Title = NULL will remove it entirely. Title = "" will provide an empty title but retain the spacing.

SubTitle

Optionally the sub-title to be displayed. SubTitle = NULL will remove it entirely. SubTitle = "" will provide and empty title but retain the spacing.

Caption

Optionally the caption to be displayed. Caption = NULL will remove it entirely. Caption = "" will provide and empty title but retain the spacing.

XTextSize

Optionally the font size for the X axis labels to be displayed. XTextSize = 12 is the default must be a numeric. Note that X & Y axis text are on different scales

YTextSize

Optionally the font size for the Y axis labels to be displayed. YTextSize = 3 is the default must be a numeric. Note that X & Y axis text are on different scales

TitleTextSize

Optionally the font size for the Title to be displayed. TitleTextSize = 14 is the default must be a numeric.

SubTitleTextSize

Optionally the font size for the SubTitle to be displayed. SubTitleTextSize = 10 is the default must be a numeric.

CaptionTextSize

Optionally the font size for the Caption to be displayed. CaptionTextSize = 8 is the default must be a numeric.

LineThickness

Optionally the thickness of the plotted lines. LineThickness = 1 is the default must be a numeric.

LineColor

Optionally the color of the plotted lines. By default it will use the ggplot2 color palette for coloring by Grouping. The user may override with one valid color of their choice e.g. "black" (see colors() for choices) OR they may provide a vector of colors such as c("gray", "red", "green", "gray", "blue") OR a named vector like c("Green" = "gray", "Liberal" = "red", "NDP" = "green", "Others" = "gray", "PC" = "blue"). Any input must be character, and the length of a vector should equal the number of levels in Grouping. If the user does not provide enough colors they will be recycled.

DataTextSize

Optionally the font size of the plotted data points. DataTextSize = 2.5 is the default must be a numeric.

WiderLabels

logical, set this value to TRUE if your "labels" or Grouping variable values tend to be long as they are in the newcancer dataset. This setting will give them more room in the same plot size.

RemoveMissing

logical, by default set to TRUE so that if any Measurement is missing all rows for that Grouping are removed. If set to FALSE then the function will try to remove and graph what data it does have. N.B. missing values for Times and Grouping are never permitted and will generate a fatal error with a warning.

Value

a plot of type ggplot to the default plot device

References

Based on: Edward Tufte, Beautiful Evidence (2006), pages 174-176.

Examples

Run this code

# NOT RUN {
# the minimum command to generate a plot
newggslopegraph(newcancer, Year, Survival, Type)

# adding a title which is always recommended
newggslopegraph(newcancer, Year, Survival, Type, 
                Title = "Estimates of Percent Survival Rates",
                SubTitle = NULL,
                Caption = NULL)
                
# simple formatting changes
newggslopegraph(newcancer, Year, Survival, Type, 
                Title = "Estimates of Percent Survival Rates", 
                LineColor = "darkgray", 
                LineThickness = .5, 
                SubTitle = NULL, 
                Caption = NULL)
                
# complex formatting with recycling and wider labels see vignette for more examples
newggslopegraph(newcancer, Year, Survival, Type, 
                Title = "Estimates of Percent Survival Rates", 
                SubTitle = "Based on: Edward Tufte, Beautiful Evidence, 174, 176.",
                Caption = "https://www.edwardtufte.com/bboard/q-and-a-fetch-msg?msg_id=0003nk",
                LineColor = c("black", "red", "grey"), 
                LineThickness = .5,
                WiderLabels = TRUE)


# }