link.join Function (GPL)

Syntax

link.join(<algebra>)

or 

link.join(<binning function>)

or 

link.join(<statistic function>)

<algebra>. Graph algebra, such as x*y. Refer to Brief Overview of GPL Algebra for an introduction to graph algebra.

<binning function>. A binning function.

<statistic function>. Another statistic function. The result of the embedded statistic is used to calculate link.join.

Description

Joins sets of points from a blend. link.join may be used for repeated measures or observations over time, among others. In all cases, there is a blend that defines the relation. This distinguishes link.join from the other link functions.

Examples

Figure 1. Example: Creating a bridge plot
ELEMENT: edge(position(link.join(x1*y1 + x2*y2)), label(a))
ELEMENT: point(position(x1*y1 + x2*y2), label("Before"+"After"))

This example assumes data that is in a format like the following:

Table 1. Example data
a x1 y1 x2 y2
Bill 45 50 58 67
Alice 32 40 33 40
Bob 22 31 26 35
Audrey 55 59 52 64
Figure 2. Example: Drawing vectors from the origin
TRANS: zero = eval(0)
ELEMENT: edge(position(link.join(zero*zero + x*y)), shape(shape.arrow))

Statistic Functions

See GPL Functions .