R: Plotting NBER Recesssions in the ggplot graphics system

nberShade.ggplot {tis}

R Documentation

Plotting NBER Recesssions in the ggplot graphics system

Description

nberShade.ggplot is a method for shading recession areas in a plot of class ggplot. It calls nberDates to get x coordinates for the areas to be shaded and then passes those coordinates along with its own arguments to geom_rect to do the shading. It may also draw a vertical line at the appropriate location if openShade is false and its xrange is of an appropiate size.

Usage

## S3 method for class 'ggplot'
nberShade(gg = ggplot2::last_plot(), fill = "grey80", color = NA, size = 0.5, 
                        alpha = 0.5, xrange = NULL, openShade = TRUE, ...)

Arguments

`gg`	A `ggplot` object that contains a mapping of `y` to its `data`. The default is to use the last `ggplot` object that was plotted.
`fill`	color to shade recessionary periods, passed to `geom_rect`.
`color`	The default (`NA`) omits borders on the shaded regions. Alternatively, specify a border color. Passed to `geom_rect`
`size`	A number specifying how thick should the border lines be. Passed to `geom_rect`
`alpha`	A number specifying how transparent the shaded regions should be. Passed to `geom_rect`
`xrange`	Horizontal range over which recession shading should be drawn. The default value `NULL` uses the entire range of the recession dates. `xlim` and `scale_x_date` are convenient `ggplot2` functions to afterwards restrict the plot to a more sensible range.
`openShade`	governs how `nberShade` handles the case where the last row of the matrix returned by `nberDates` has an `NA` in the "End" column, indicating that the end date of the most recent recession is not yet known. If `TRUE` and `xrange` has been specified and extends far enough into the future it will replace the `NA` with `xrange[2]`. Else if `openShade` is `TRUE` and `xrange` is `NULL` then it will replace the `NA` with `Sys.Date()`. If `openShade` is `FALSE` then `nberShade` will draw a vertical line at the start of the most recent recession.
`...`	not used, present only to match generic

Value

Returns a ggplot object.

Note

Recessions are dated by the Business Cycle Dating Committee of the National Bureau of Economic Research.

References

National Bureau of Economic Research. http://www.nber.org.

Examples

    ## Not run: 
        require("ggplot2")
        ggp <- ggplot(aes(x=date, y=100*unemploy/pop), data=economics)

        nberShade( ggp ) + xlim(as.Date("1967-01-01"), Sys.Date()) + 
        opts(legend.position="none") + geom_line() + theme_bw()

        nberShade( ggp, fill = "yellow", color = "pink",                      
                xrange = c("1969-01-01", "2008-02-01"), openShade = FALSE) + 
        opts(legend.position="none") + geom_line(size=1) + theme_bw()
    
## End(Not run)

[Package tis version 1.30 Index]