Parallel Coordinates

Parallel coordinates is a technique pioneered in the 1980's which has been applied to a diverse set of multidimensional problems [11,22].  In this technique, each data dimension is represented as a horizontal or vertical axis, and the N axes are organized as uniformly spaced lines. A data element in an N-dimensional space is mapped to a polyline that traverses across all of the horizontal or vertical axes.

Advantages

• The number of dimensions that can be visualized is only restricted by the horizontal resolution of the screen, though as the axes get closer it may become more difficult to perceive structures or data relations.
• Correlations between variables in the dataset can be spotted easily.

Disadvantage

• Level of clutter present in the visualization reduces the amount of useful information one can perceive.  (See example below).

Figure 1: Parallel coordinates display of a 5-dimensional dataset with 16,384 records. Note the amount of over-plotting that precludes the presence of any data trends, for instance the relative densities.