IBM Visualization Data Explorer User's Reference

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Plot

Category

Annotation

Function

Creates a 2-dimensional plot.

Syntax


plot = Plot(input, labels, ticks, corners, adjust, frame, type, grid,
            aspect, colors, annotation, labelscale, font, input2,
            label2, ticks2, corners2, type2,

            xticklocations, y1ticklocations, y2ticklocations,
            xticklabels, y1ticklabels, y2ticklabels);

Inputs
Name Type Default Description
input field or group none data to be plotted
labels string list {"x," "y"} axis label
ticks integer list 10 approximate number of tick marks
corners vector list or object {[xmin, ymin],
[xmax, ymax]}
plot limits
adjust flag input dependent 0: end points not adjusted
1: end points adjusted to match tick marks
frame integer 0 framing style for plot
type string list "lin" plot type
grid integer 0 grid style
aspect scalar or string 1.0 y:x (aspect) ratio of resulting plot
colors vector list or string list appropriate colors for annotation
annotation string list "all" annotation objects to be colored
labelscale scalar 1.0 scale factor for labels
font string standard font for labels
input2 field or group no default second set of data to be plotted
label2 string {"y2"} label for second y-axis
ticks2 integer input dependent approximate number of tick marks for second y-axis.
corners2 vector or object {[ymin, ymax]} plot limits for second y-axis
type2 string "lin" plot type for second y-axis
xticklocations scalar list appropriate x tick locations
y1ticklocations scalar list appropriate y1 tick locations
y2ticklocations scalar list appropriate y2 tick locations
xticklabels string list xticklocations x tick labels
y1ticklabels string list y1ticklocations y1 tick labels
y2ticklabels string list y2ticklocations y2 tick labels

Outputs
Name Type Description
plot field the plot

Functional Details

This module creates a 2-dimensional plot from a line or set of lines. The following plot characteristics can be set on the line or lines with the Options module (in the Structuring category) before they are passed to Plot: line label, line marker type, marker size, number of markers, and the choice of creating a scatter plot or not (see "Creating a Legend", "Using Line Markers", and "Scatter Plots").

input

is a field or group of fields, where each field has 1-dimensional positions representing the "x"-values, and 1-dimensional data representing the "y"-values. If the input is a group of Fields, each Field is plotted as a separate line.

There can be a "connections" component of element type "lines" connecting the positions; if a connections component for a given Field does not exist, the module adds one. The input can have a "colors" component, in which case the output plot preserves those colors. If the input does not have a "colors" component, the line is colored white.

labels

specifies the labels for the axes of the plot.

ticks

specifies the number of tick marks to be placed on the plot axes. The default is 10.

If the parameter value is a single integer, then approximately that many tick marks are placed along the axes. If the parameter list is a two-element integer list, the first element is interpreted as the approximate number of tick marks to be placed on the x-axis; the second element, the approximate number to be placed on the y-axis.

corners

specifies the limits of the plot axes. (The default limits are set by the input line or lines.) The specification can be a vector list or an object. If the specification is a vector list, then all points that lie outside of corners are eliminated from the plot. If the specification is an object (such as a group of lines), the module determines the minimum and maximum x- and y-values for the entire object and uses those to set the plot limits.

adjust

determines whether the axes end at tick marks or not.

frame

determines how the plot is framed. In all cases, axes and tick labels are drawn on the left side and bottom of the plot. For frame = 1, additional lines (without ticks) are drawn on the right side and top of the plot. For frame = 2, lines and major and minor ticks are drawn on the right side and top of the plot.

type

specifies the plot type. It is a string or string list and must be:

  1. "lin" (linear plot)
  2. "log" (logarithmic plot)
  3. any two-element combination of these (e.g., {"lin," "lin"} or {"log," "lin"}). If type is a single string, both the x- and the y-axis are of that type. If type is two strings, then the first string applies to the x-axis while the second string applies to the y-axis.

grid

specifies whether and how to draw grid lines along major ticks. If grid = 0, no grid lines are drawn. If grid = 1, then grid lines are drawn horizontally along major ticks. If grid = 2, then grid lines are drawn vertically along major ticks. If grid = 3, grid lines are drawn both horizontally and vertically along major ticks. If grid is not equal to 0, adjust is set to 1.

aspect

allows you to set the approximate y:x aspect ratio of the resulting plot. You can also use the Scale module before Plot to adjust the aspect ratio. The default is an aspect ratio of 1.0. If you want Plot to simply use the actual aspect ratio of the data, set aspect to "inherent". Note that if a second plot is drawn (i.e. input2 is provided), aspect is set to 1.0 even if "inherent" is specified.

colors

together with annotation (see below), can be used to set the color of one or more components of the plot.

colors: specifies a single color (an RGB vector or color-name string) or a list of colors. Color-name strings must be from the list of defined color strings (see Color).

If colors is a single string and annotation is not specified or is "all," then that color is used for all axes annotation. Otherwise, the number of colors in colors must match the number of annotation strings exactly and in one-to-one correspondence. By default, a background is not drawn.

annotation

can be one of the following: "all," "axes," "background," "grid," "labels," or "ticks."

labelscale

allows you to change the size of the axes and tick labels. For example, to make the labels twice as large, specify labelscale = 2.

font

specifies the font used for labels. The default is "standard," which uses a fixed font for the tick-mark labels and a variable font for the axes labels. You may specify font as any of the defined fonts supplied with Data Explorer:

area          gothicit_t       pitman                roman_ext
cyril_d       greek_d          roman_d               script_d
fixed         greek_s          roman_dser            script_s
gothiceng_t   italic_d         roman_s               variable
gothicger_t   italic_t         roman_tser
For more information, see Appendix E. "Data Explorer Fonts" in IBM Visualization Data Explorer User's Guide.

The Plot module can also generate a second set of lines and a second y-axis on the right side of the plot. If a second plot is drawn, the aspect ratio defaults to 1. For this second plot and axis, you must repeat several specifications:

input2

is a second field or group of fields (see input above).

label2

is the label for the second y-axis.

ticks2

is the approximate number of ticks for the second y-axis. A negative integer specifies outward, as opposed to inward, pointing ticks.

corners2  (see corners

specifies the min and max for the second "y"-axis.

type2

specifies the type of second y-axis and must be either "log" or "lin."

xticklocations

explicit set of tick locations for the x axis. If specified, overrides the values for tick locations as determined from ticks.

y1ticklocations

explicit set of tick locations for the first y axis. If specified, overrides the values for tick locations as determined from ticks.

y2ticklocations

explicit set of tick locations for the second y axis. If specified, overrides the values for tick locations as determined from ticks.

xticklabels

list of labels to be associated with the specified xticklocations. If xticklabels is specified and xticklocations is not specified, then xticklocations to the integers 0 to n-1, where n is the number of items in xticklabels.

y1ticklabels

list of labels to be associated with the specified y1ticklocations. If y1ticklabels is specified and y1ticklocations is not specified, then y1ticklocations to the integers 0 to n-1, where n is the number of items in y1ticklabels.

y2ticklabels

list of labels to be associated with the specified y2ticklocations. If y2ticklabels is specified and y2ticklocations is not specified, then y2ticklocations to the integers 0 to n-1, where n is the number of items in y2ticklabels.

Creating a Legend

To create a legend for the plot, use Options to set a "label" attribute on the incoming lines. Plot will then create an appropriate plot legend and place it in the upper right corner (see the first example below). The legend contains a short line segment with a color matching that of the line it corresponds to, along with the label for the line. The "label" attribute can also be set in the Data Explorer file format (see Appendix B. "Importing Data: File Formats" in IBM Visualization Data Explorer User's Guide).

Using Line Markers
You may also choose markers for your plot lines. You may set a "mark" attribute on the input lines using the Options module. "mark" should have as a value one of the following: "circle," "diamond," "dot," "square," "star," "triangle," or "x." By default, a mark is placed at every point on the line. You can also set a "mark every" attribute with an integer as a value. For example, the value 3 would cause every third point to be marked. You can control the size of the mark using the "mark scale" attribute, which applies a scale factor to the default mark size. For example, a "mark scale" value of 2 would make the marks twice as large. If you are using the "label" attribute, the mark will also appear in the legend.

Note: The "dot" mark type will only be visible if you also set the "scatter" attribute to 1 (see "Scatter Plots").

Different colored lines
If you want your lines to have different colors, simply pass them through the Color module before passing them to Plot.

Scatter Plots
To create a scatter plot (with no line drawn between markers), set the "scatter" attribute on the line to 1 (one). (The default is a line between markers.)

Notes:

  1. If corners is more restrictive than the ticklocations, then the given locations outside the corners are not shown.

  2. If corners is less restrictive than the given ticklocations, or if corners is not specified, then all given tick locations are shown, whether or not there is data there.

  3. If ticklocations is specified, then the data range determines the extent of the axes, unless corners is specified, in which case the given corners are used.

Bar Charts

If the input to Plot has a "data" component that is dependent on "connections" rather than "positions," a bar chart is created.

Components

Creates "positions," "connections," and "colors" components.

Example Visual Programs

PlotLine.net
PlotLine2.net
PlotTwoLines.net

PlotSpecifyTicks.net

See Also

 Compute,  Construct,  Histogram,  Options


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