Dataplot: Spikes


Dataplot: Spikes
Introduction	Dataplot can draw a curve as a character or plot symbol at each point, as a connected line, as a spike from the point to a base, as a bar from the point to a base, or as any combination of the above (including drawing none or all of them). The choice is determined by the LINE, CHARACTER, SPIKE, and BAR commands. The switches for these commands work independently of each other.
Description	A spike is a vertical line from the plot point to the spike base (often the x axis, but it can be other values such as the mean). The spike is most often drawn as a solid line, but you can draw it using a dash or dot pattern as well. The available line patterns are the same as for drawing lines.
Some Common Usage	Spikes are commonly used in time series plots. They are also useful in showing deviation from a common value such as the mean or median. They are also used to draw dot charts, which are an alternative to bar plots recommended by Bill Cleveland in the book "Elements of Graphing Data".
Use of Short Forms	The short designations (e.g., BL for BLANK, SO for SOLID, DA3 for DASH3) allow for the specification of a large number of spike types on a single command line, as in SPIKE SO SO SO SO SO DO DO DO DO DO ... DA DA DA DA DA
How Dataplot Decides Which Spike Pattern to Use	For single-trace plots, as from PLOT Y X Dataplot makes use of the first spike type specified. For multi-trace plots, as from PLOT Y1 Y2 Y3 Y4 Y5 VS X PLOT Y X TAG Dataplot makes use of the respective spike types for each trace; thus the first spike type defines the type for the first trace, the second spike type defines the type for the second trace, and so forth.
Dataplot Program Demonstrating the Attributes of Spikes	Dataplot allows you to set the base, line style, thickness, and color of the spike as demonstrated by the following Dataplot program. SKIP 25 READ BOXJE142.DAT YIELD . TITLE TIME SERIES PLOT Y1LABEL YIELD X1LABEL SEQUENCE NUMBER XLIMITS 0 70 XTIC OFFSET 2 2 LET N = SIZE YIELD LET A = MEAN YIELD CHARACTER OFF SPIKE ON LINE BLANK . MULTIPLOT 2 2 MULTIPLOT CORNER COORDINATES 0 0 100 100 PLOT YIELD . SPIKE BASE A PLOT YIELD LINE SOLID DRAWDATA 1 A N A LINE BLANK . SPIKE THICKNESS 0.3 PLOT YIELD LINE SOLID DRAWDATA 1 A N A LINE BLANK . SPIKE COLOR BLUE LINE SOLID LINE COLOR BLUE PLOT YIELD DRAWDATA 1 A N A END OF MULTIPLOT
Dataplot Graph	The above program generated the following Dataplot graph.
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