# Parallel Coordinates Introduction

To create a parallel coordinate plot, you first lay out an axis for each variable of interest. In this demonstration, we have four variables we wish to explore.

Each data point in a data set has a particular value for each of the four variables, creating an intersection point on each of the four axes. We connect those intersections with lines, creating a multi-axis representation of a single data point.

So far, so good. Let's add another data point.

And more...

Interesting. We can start seeing trends in the data. Let's add all of the data points in the mesh.

Ack! This method doesn't scale. We need a better representation.

VisIt can calculate a density of the lines, in essense a 2 dimensional histogram for each pair of axes, and directly plot that.

That's nice! We can see the trends of the data.

We can also turn on the Axis Restriction tool and limit the data.

That's neat! We can see both the focus area we defined with the Axis Restriction tool and the context in which that data selection sits.