\section{Spark graphics: line, bar and win-loss}
\begin{demo}{Comparable monthly observations}
\gradbarsstyle{monthly}{width=65mm,height=7mm,min=0,max=100,
  spark range=fixed,precision=0,row padding=3pt}
\begin{center}
\begin{tabular}{@{}cc@{}}
\toprule
\multicolumn{1}{c}{Series} & \multicolumn{1}{c}{Jan--Jun / June value}\\\midrule
North & \gradspark[style=monthly]{35,48,42,60,72,80}\\
South & \gradspark[style=monthly]{55,53,NA,58,62,65}\\
West & \gradspark[style=monthly]{45,45,45,45,45,45}\\
East & \gradspark[style=monthly]{30,40,55,60,70,NA}\\
\bottomrule
\end{tabular}
\end{center}
\end{demo}
Observations are equally spaced. Empty fields and NA keep their horizontal
position and break connections. The last label is the last position, not the last
nonmissing observation. Default height is 4ex.

\key{spark range=auto} uses each row's extrema; compare shapes only with this mode.
Use fixed with shared min, max, width and height to compare magnitudes across rows.
Constant auto series are centered vertically; a singleton is centered horizontally.
All-missing series show only a track and missing label. Fixed ranges use normal
overflow rules. Auto ranges do not support computed-percent labels.

\key{spark points} can be extrema (default), all, last or none. Extrema mode
marks all tied extrema and the last position if present. Low and high colors
default to gradbarsOrange and gradbarsTeal. A constant series uses the high color;
a non-extreme last point uses the line color. Point colors indicate position, not
quality. Use color, stem width and marker size to style the line and points.
Sparklines do not parse dates and do not use bar targets, error whiskers, bands or
thresholds. Labels stay outside. Use a common observation grid for irregular dates.
\clearpage

\subsection{Bar sparks preserve magnitudes}
\key{spark type=bar} draws signed bars in equally sized observation slots.
Automatic ranges include zero; fixed ranges use min/max and normal overflow
rules. Keep ranges shared when comparing rows.
\begin{demo}{One series shown as line, bar and win-loss}
\gradspark[width=65mm,height=7mm,precision=0]{20,-10,NA,40,0,-30}

\gradspark[spark type=bar,width=65mm,height=7mm,
  precision=0]{20,-10,NA,40,0,-30}

\gradspark[spark type=winloss,width=65mm,height=7mm,
  precision=0]{20,-10,NA,40,0,-30}
\end{demo}
\key{spark bar width} defaults to .7 of a slot and must be in (0,1]. Positive
bars use the regular fill; negative bars use negative color. Zero draws a short
baseline stroke; missing leaves a gap. All-zero/all-missing auto bars use [0,1].
\subsection{Win-loss sparks show signs only}
\key{spark type=winloss} maps positives to wins, negatives to losses and zero
to ties. Fixed category heights do not express magnitudes; min/max and spark
range do not affect the classification. Use spark win color, spark loss color
and spark zero color to style categories and the baseline.
Both discrete modes retain every position and the raw last-value label; a missing
last position retains its missing label. Win-loss rejects computed-percent labels.
Print uses grayscale. Spark points and extrema marker colors apply only to line
mode. In \key{gradtable}, use \key{type=spark} with \key{spark type=bar} or winloss in options.