{smcl}
{* 9jan2004}{...}
{hline}
help for {hi:circdplot}
{hline}
{title:Raw data plot for circular data with point symbols}
{p 8 17 2}
{cmd:circdplot}
{it:varname}
[{cmd:if} {it:exp}]
[{cmd:in} {it:range}]
[{cmd:,}
{cmdab:cla:bel(}{it:label_specification}{cmd:)}
{cmdab:ctic:k(}{it:numlist}{cmd:)}
{cmd:fudge(}{it:#}{cmd:)}
{cmdab:result:ant(}{it:resultant_options}{cmd:)}
{cmd:round(}{it:#}{cmd:)}
{cmdab:tick:length(}{it:#}{cmd:)}
{cmd:unit(}{it:#}{cmd:)}
{it:twoway_options}
]
{title:Description}
{p 4 4 2}
{cmd:circdplot} produces a raw data plot for {it:varname} with point symbols
showing values. {it:varname} should be a circular variable taking on values
between 0 and 360 degrees.
{p 4 4 2}
Strictly, the values of {it:varname} are rounded to the nearest degree, or to
the argument of {cmd:round()}. Rays of point symbols are drawn outwards from
the circumference of a circle pointing in each direction present in the data.
The length of each ray is proportional to the frequency of that direction.
The resultant or mean direction is indicated by an arrow from the centre of the
circle with length the radius of the circle X the vector strength. Hence an
arrow representing a mean direction with vector strength 1 would touch the
circle.
{p 4 4 2}
The graph will usually best be shown with {cmd:xsize()} and {cmd:ysize()}
equal, or nearly so. It may be helpful to know that the centre of the circle is
at {it:x} = 0, {it:y} = 0 and that it has radius 1, so that the cardinal points
North, East, South, West are at 0,1; 1,0; 0,-1; -1,0.
{title:Options}
{p 4 8 2}
{cmd:clabel()} specifies labels to be shown inside the circle at angles
measured clockwise from 0 (North) through 360 degrees. Single text labels
may be specified within {cmd:" "} following each label. For example,
the default is {cmd:clabel(0 "N" 90 "E" 180 "S" 270 "W")}.
{p 4 8 2}
{cmd:ctick()} specifies positions of ticks to be shown inside the circle
at angles measured clockwise from 0 (North) through 360 degrees.
{p 4 8 2}
{cmd:fudge()} specifies a fudge factor controlling the radial spacing of point
symbols. Default 1 means that the outermost point symbol will be
plotted at distance from the circle equal to the radius of that
circle. # means maximum distance # X that radius. Most graphs will
need some hand-tuning of {cmd:fudge()} for better appearance. See
also {cmd:round()}.
{p 4 8 2}{cmd:resultant()} specifies options controlling the rendering of the
arrow showing the resultant. In particular, {cmdab:arrowhead:length()} specifies
the arrowhead length (default 0.1). Otherwise, such options are typically
appropriate {help connect_options}.
{p 4 8 2}
{cmd:round()} indicates the bin or class width to be used (default 1 deg).
See also {cmd:fudge()}.
{p 4 8 2}
{cmd:ticklength()} specifies the tick length (default 0.05).
{p 4 8 2}
{cmd:unit()} specifies that a point symbol should represent at most {it:#}
observations, which number should be >= 1. That is, {cmd:unit(10)} specifies
that a point symbol should represent at most 10 observations. Strictly,
frequencies in each bin will be rounded up to the nearest multiple of {it:#},
so that with {cmd:unit(10)} 1 to 10 observations would be represented by one
point symbol, 11 to 20 two symbols, and so forth.
{p 4 8 2}
{it:twoway_options} are options of {help twoway_options:twoway}.
By default the {cmd:subtitle()} indicates the mean direction and vector
strength and is at {cmd:pos(6)}. Note that the degree symbol can be specified
by {cmd:`=char(176)'}.
{title:Example}
{p 4 8 2}{cmd:. circdplot wallasp, result(clcolor(blue) clw(thick)) round(2) fudge(0.25) ms(Oh) mcolor(red) text(-0.5 0 "Wall aspect", size(large))}{p_end}
{p 4 8 2}{cmd:. graph display, xsize(4) ysize(4)}
{title:Author}
{p 4 4 2}
Nicholas J. Cox, University of Durham, U.K.{break}
n.j.cox@durham.ac.uk
{title:Also see}
{p 4 13 2}
On-line: help for {help circrplot} (if installed),
{help circvplot} (if installed)