hplot and hbar for presentation graphics

Speaker:  Nicholas J. Cox, Durham University, UK

hplot and hbar are basic presentation graphics programs using gph. Stata 6 is required. Driver programs have been written for hplot and hbar automating various common tasks: cihplot shows confidence intervals (calls up ci), tabhplot and tabhbar display one- or two-dimensional tables of frequencies in graph form (counting is done internally), and hbox uses hbar to provide an alternative to graph, box. They are all downloadable from the SSC-IDEAS archive.

hplot, for horizontally labelled plots, shows one horizontal line for each observation included with one or more point symbols using a common scale. It can produce a variety of plots, including

  • W.S. Cleveland's dot charts or dot plots
  • variations on them with continuous lines
  • D.R. McNeil's horizontal parallel line plots
  • displays of key quantities with/without confidence intervals

By default, data are on dotted lines with base zero that extend to the maximum for each observation. If negative values are present, such dotted lines also extend to the minimum for each observation.

If grid option: horizontal dotted lines extend over whole data region.
If line option: horizontal continuous lines with base at left-hand margin.
If range option: horizontal dotted or continuous lines extend only over range of values for each observation.
If data allow, a different base may be forced using xscale().

The legend on left can be from a specified variable: it is right-justified and should look readable up to about 30 observations.

The user can force extra gaps between lines and tune magnitude of those gaps. Extra legends may be inserted in such gaps.

The order of lines can be controlled by sorting on any variable(s).

The standard symbol set of graph has been extended to include vertical bars, arrows, and crosses.

The large title() may be put at the top of the graph.

The user may control font sizes.

hbar for horizontal bar charts has many of the same features as hplot.

Bars for different variables stacked with base at 0: optionally, bars may be horizontal lines with or without vertical lines at either or both ends.

The shading set of graph has been extended to include empty (unshaded) and invisible bars.

The user can tune the fraction of vertical space taken up by bars (1 means bars touch).

Values may also be shown as text, either inside or outside bars.