Internal Calculations for Time Series Plotting

DESCRIPTION:

Compute the tick marks, axis breaks, grid lines, or scale of the time axis, for plotting a calendar time series. These functions are all meant to be called from axis.time.

USAGE:

axis.time.ticks(axis.info, levels=c("small", "medium", "big"), at=NULL,
   level.override="medium") 
axis.time.breaks(axis.info, width=.05, max.width=.15) 
axis.time.grid(label.info) 
axis.time.scale(axis.info, break.info) 

REQUIRED ARGUMENTS:

axis.info
the output from axis.time.build.
label.info
the output from axis.time.labels.
break.info
the output from axis.time.breaks.

OPTIONAL ARGUMENTS:

levels
a vector of character strings indicating which tick marks are to be displayed. Up to three types of tick marks are supported: "small", "medium", and "big".
width
the width of each break as a fraction of the plottting region.
max.width
the maximum total width taken up by axis breaks, as a fraction of the plotting region.
at
if not NULL, place the ticks at tick level level.override at these values, instead of at "pretty" values. Must be a vector of timeDate values, or something that can be converted to timeDate values.
level.override
tick level to override with the values of at.

VALUE:

Each function returns a list suitable for passing to axis.render or grid.render that contains parameters for generating axis ticks, axis breaks, or grid lines. axis.time.ticks returns a list with components named as in levels: small controls the small, frequent tick marks; medium the medium tick marks; and big the large, least frequent tick marks. Each of the sets of tick parameters is a list containing an at component, telling where to put the ticks, in time coordinates, generated by calling timeSeq using the by and k.by parameters in axis.info. axis.time.breaks returns a list with an at component telling where to put the breaks (generated from axis.info$intervals$close), and a width component giving the width of the breaks (this may not be the same as the width argument, if the total width of breaks would have exceeded max.width). axis.time.grid returns a list with up to two components: major.grid and minor.grid; each component is a list containing an x component telling where the grid lines should be, which come from the label positions label.info$outer.label and label.info$main.label respectively; if label.info has no names, it is treated as being the main.label list only. axis.time.scale returns an axis scale list, whose first component is a vector of times and second component is a vector of corresponding numeric values. Since internal plotting functions only deal with numbers, the time values for plotting are transformed to numbers using this scale, linearly interpolating between the values. The scale is calculated taking into consideration axis breaks and axis.info$skip.weekends. The other tick, break, and grid parameters use the default values from trellis.par.get ; for more information see axis.render and grid.render.

SEE ALSO:

, , , , , , .