proc scatterplot


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Manual page for proc_scatterplot(PL)

DESCRIPTION

Displays data points in one or two dimensions.

FEATURES

Clustering of duplicate data points.

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

User control over point shapes, colors, sizes.

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

EXAMPLES

See the Gallery Scatterplot page

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 and 1-dimensional. 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. Characters/text may be a literal or it may come from a data field.

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 X.

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). 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 of length n in absolute units . The 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. Example: linelen: 0.2

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

labelfield dfield

If specified, data points will be displayed using the contents of data field dfield, centered around the data point. 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.
Example: legendlabel: Group 4, N=@NVALUES

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.

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.

clusterfact n

May be used when clustering is being done. The offset that used to display duplicate data points 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.

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.

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


data display engine  
Copyright Steve Grubb


Markup created by unroff 1.0,    June 18, 2001.