XY-sets in Mesh

An XY-set is a set of two-dimensional curves. Mesh supports storing XY-sets in XY-set XY-set attributes, which can be versioned or unversioned. This document will explain what XY-curves and XY-sets are, how Mesh XY-set attributes are structured, and how you can use the Mesh Python SDK to access the XY-sets in those attributes.

XY-curves

An XY curve is a set of (x, y) pairs where x and y are 64 bit floating point values.

x

y

1

2

2

1.5

3

0.5

10

-1

XY-sets

An XY set is a set of XY curves, each curve indexed by a 64 bit floating point reference value. These reference values are sometimes called Z. We often visualize XY sets like so:

x
z
y
z
y

0

180

1.5

0.3

3

0.5

1

10

-1

9

  • The first non-header row contains the reference/Z values for that column.

  • Usually the headers will have actual names, see further below.

A versioned XY set is a versioned list of XY sets. Each XY set in the list has a timestamp which indicates the start of the active period for that XY set, and the XY set is active until the next time-sorted XY set in the versioned XY set becomes active.

Mesh has attribute types for XY sets (XYSetAttribute) and versioned XY sets (XYZSeriesAttribute). In the attribute definitions of those attributes we store a description and a unit of measurement for each of X, Y, and Z. For example if we have the following axis definitions…

Axis

Description

Unit of measurement

X

Wind speed

m/s

Y

Production

MW

Z

Wind direction

degrees

…Nimbus will visualize the above XY set as:

Wind speed [m/s]
Wind direction [degrees]
Production [MW]
Wind direction [degrees]
Production [MW]

0

180

2

1.5

0.3

3

0.5

1

10

-1

9

Accessing XY-set values using the Python SDK

XY-sets and XY-curves are represented in Python by the volue.mesh.XySet and volue.mesh.XyCurve classes. See their respective documentation for more information.

To access or update XY-sets you can use the volue.mesh.Connection.Session.get_xy_sets() and volue.mesh.Connection.Session.update_xy_sets() methods. See their respective documentation for more information.