Manual page for proc_scatterplot(PL)

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proc scatterplot


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DESCRIPTION

Displays data points in one or two dimensions.


FEATURES

Clustering (using a small offset) of duplicate data points.

Data points may be marked with geometric point symbols, characters/text, lines, or rectangles.

User control over point shapes, colors, sizes.

Optional labelling from data, and control of point size from data.

HTML clickmap support for data points.


EXAMPLES

Gallery scatterplot examples and heatmap examples


VARIABLES THAT ARE SET

NVALUES = the number of in-range plottable points that were rendered. Note: this may be used in the legendlabel.


UNPLOTTABLE DATA

proc scatterplot will omit data points that are not valid or not within the plotting area.


PREREQUISITES

A plotting area must be set up using proc areadef and proc getdata must be executed to access or define some data.


MODES

2-dimensional (2-D) and 1-dimensional (1-D). For 2-D scatterplots, both xfield and yfield should be specified.

With 1-D scatterplots points are plotted along an imaginary line. To distribute points horizontally along Y=1 for example, ylocation: 1 and xfield should be specified. To distribute points vertically along X=5, xlocation: 5 and yfield should be specified.

Data points may be marked with geometric point symbols and/or characters/text, or using short line segments. Rectangles may also be used. Characters/text may be a literal or it may come from a data field. It is also possible to have the geometric point symbols or rectangle colors controlled by a datafield (symfield, symrangefield).


DUPLICATE POINTS

The cluster attribute (which is on by default) causes duplicate points to be offset slightly to form a cluster or bar, which often gives a satisfactory visual representation of the degree of duplicity. It is also possible to show duplicity using different symbol colors, sizes or shapes (dupsleg).


MANDATORY ATTRIBUTES

For a 2-D scatterplot both xfield and yfield must be specified. For a 1-D scatterplot, either xfield or yfield must be specified.


ATTRIBUTES

xfield dfield

Get X plotting values from this data field. First field is 1. Example: xfield: 1

yfield dfield

Get Y plotting values from this data field. First field is 1. Example: yfield: 1

xlocation locvalue

If specified, proc scatterplot will operate in 1-D mode along Y. The value specifies where the points will be rendered in X.

ylocation locvalue

If specified, proc scatterplot will operate in 1-D mode along X. The value specifies where the points will be rendered in Y.

cluster yes | no

If yes, data will be sorted on X,Y and duplicate data points will be detected and offset slightly to show duplicity. The default is yes. Clusters may be as large as N=36 (after this, points will overlap). Additional attributes related to clustering are described below. Note: If labelfield and/or sizefield are being used, clustering will work properly only when data are presorted into X,Y order.

symbol symboldetails

If specified, a geometric point symbol will mark data points. This specifies the attributes of the symbols to be used.
Example: symbol: style=fill shape=circle fillcolor=red

linelen n

If specified, data points will be displayed as lines instead of a dot or other symbol, and the lines will be of length n in absolute units. The default direction of the line will be appropriate for 1-D scatterplots; for 2-D it is horizontal. Line color, etc. may be controlled using linedetails. Line length may also be influenced using sizefield. Line direction may be explicitly controlled using linedir. Example: linelen: 0.2

linedir h|v|u|r

Allows explicit control of direction of line, when linelen is used to render lines instead of dots or other symbols. h = horizontal (centered); v = vertical (centered); u = upward; r = rightward. Example: linedir: v

text text

If specified, data points will be displayed using the given text, centered around the data point. This attribute may be used with or without a symbol. Example: text: A

rectangle width height [ outline ]

Data points will be displayed using a rectangle centered around the data point of width data units wide and height data units high. If outline is specified, the rectangles will be outlined with a line (controllable using linedetails). The color of the rectangle can be controlled via a datafield (see symfield, symrangefield, and dupsleg below).
Example: rectangle 1 1 outline
Example: rectangle 0.9 0.9

labelfield dfield

If specified, data points will be displayed using the contents of data field dfield, centered around the data point. May not be used with symbol; in order to do datafield-driven label plus a symbol proc scatterplot must be invoked twice.
Example: labelfield: 4

textdetails textdetails

Details concerning the rendering of point labels.
Example: textdetails: size=6

linedetails linedetails

If points are displayed using line segments (linelen), this attribute allows control of color, line width, etc.

legendlabel text

A label to be associated with the current set of points in the legend. proc legend must be executed later in order to render the legend. @NVALUES may be used to signify number of points rendered. If proc getdata field names are being used, use of the special symbols #usexname (or #useyname) causes the field name of xfield (or yfield) to be automatically used as the legend label (new in 2.04).
Example: legendlabel: Group 4, N=@NVALUES
Example: legendlabel: Round 2
Example: legendlabel: #useyname

verticaltext yes | no

If yes, label text will be rendered vertically. This might be useful when labels are > 1 character long and data are close together in X.

sizefield dfield

Allows the size of point markers or lines to be controlled by a datafield, effectively allowing another variable to be presented.
If data points are marked using geometric symbols or text, the value in dfield will cause the marks to correspond to character point sizes. For example, a data value of 10 would yield a data point mark 10 points in height. The sizescale attribute may be used to scale the sizefield data appropriately.
If data points are marked using lines, the value in dfield will scale the length of the lines. For example, a data value of 1.0 would leave the line length unchanged, while 2.0 would double it and 0.5 would halve it.

sizescale n

May be used with sizefield when the size of data point symbols or text is being controlled by a datafield. This attribute may be used to scale the size of the point symbols to the desired range. It assumes the symbol is a circle and scales the area rather than the diameter or radius. A value of 1.0 would leave the size unchanged, while 2.0 would double the resulting size, and 0.5 would halve it.

clustermethod 2d | horiz | vert | upward | rightward

Explicitly control the way that duplicate points will be clustered. Default method is 2d for 2-D scatterplots, horiz for 1-D scatterplots where Y location is fixed, and vert for 1-D scatterplots where X location is fixed. upward and rightward may be used to string duplicate points upward or rightward to form little bars. horiz will cluster duplicate points only horizontally; vert will cluster duplicate points only vertically. An example of using clustermethod: upward to form rows of little bars, is snpmap1
To represent duplicate points using different symbol colors (etc.) see dupsleg.

clusterfact n

May be used when clustering is being done. The clustering offset distance will be multiplied by this amount. A value of 1.0 would leave the clustering offsets unchanged, while 2.0 would spread clustered points out more, and 0.5 would spread them out less.

clusterdiff f

May be used when clustering is being done. Two values that are within f of each other will be considered duplicates eligible for clustering. Default value is 0.01.

clustevery n

With clustering, normally every duplicate point is offset from all the others, which may not be effective if there are large numbers of duplicate points. In order to reduce the clutter, this attribute may be used to offset only for every nth duplicate encountered.
Example: clustevery: 5 ..would result in a point having 35 duplicates represented using 7 point marks.

dupsleg yes | no

If yes the symbol color, size, shape, etc. will be controlled by the number of duplicate points counted. This uses the legend-driven technique . Each legend entry must have a tag that is an integer, and a symboldetails entry for details. Legend entries must be specified in numerical order by tag, from highest to lowest. As the scatterplot is drawn and duplicate points are detected, a count of duplicates is maintained. Then the count is compared against the set of tags (from highest to lowest). When a tag is found that is <= the duplicate count, that legend entry is chosen, and the point will be rendered using the symbol described in that entry. Example: dupsleg

symfield dfield

If specified, the symbol color, size, shape, etc. will be controlled by this data field using the legend-driven technique . If used to control symbols, symbol attributes should be given in the legend entries; if used to control rectangles, colors should be given.
Examples: symfld

symrangefield dfield

Same as symfield above, except that numeric range comparison is used when finding the appropriate legend entry, using the legend-driven technique Legend tags must be a single numeric value. Legend entries must be specified in numerical order by tag, from highest to lowest. Prospective values will be compared against legend entries in the order specified (highest to lowest); when a legend entry tag is found that is less than or equal to the contents of the symrangefield data field, that legend entry is chosen, and the point will be rendered using the symbol described in that entry. Examples: symrangefld and symrangefld

select conditional-expression

May be used to select data rows for inclusion into the scatterplot. Example: select: @3 = AA

xrange low high

If specified, only data points within the given plottable range in X will be shown. By default the points will be drawn only if within the plotting area. Example: xrange: 0 50

yrange low high

If specified, only data points within the given plottable range in Y will be shown. By default the points will be drawn only if within the plotting area. Example: yrange: 0 50

clickmapurl url template

If generating an HTML clickmap , this specifies a url template, and causes the data points (symbol or character) to be mapped. This attribute usually contains one or more embedded data field references preceded by double at-sign (@@). See HTML clickmap for more details and examples.
Example: clickmapurl: http://abc.com/mycgi?category=@@3


data display engine  
Copyright Steve Grubb


Markup created by unroff 1.0,    December 10, 2002.