The SEDRIS Data Representation Model
APPENDIX A - Classes
Irregular Axis

Class Name: Irregular Axis

Superclass - <Axis>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class is an <Axis> that does not use a constant spacing between hash marks.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

This class appears on only one page of the DRM class diagram.

Example

  1. Data taken at times 1, 2, 5, 10, 50, and 100 seconds after some start time would be collected on an <Irregular Axis>.

  2. Radiosonde data, including temperature, humidity, wind speed, and wind direction, is generally reported as a function of pressure height. Data are reported only when there is a significant change in one of the dependent variables. Accordingly, the pressure heights are captured at unpredictable, irregular intervals. They are best captured in an <Irregular Axis>.

FAQs

How should values in an <Irregular Axis> be arranged?

Values in an <Irregular Axis> shall be arranged in ascending order.

If I am missing a few values from a regular sequence, should I use an <Irregular Axis>?

It depends how many values are missing. If there are only one or two values missing from a long regular sequence, it may be preferable to use a <Regular Axis> and mark the missing data points with the appropriate <Property Characteristic>.

My data was taken on an irregular set of points on a surface. Should I use <Irregular Axes> to indicate the 2-dimensional locations of these points?

If the data were truly irregular, which is to say that there is only one point at each x-value and only one point at each y-value, do not use irregular x- and y-axes. Instead, use a single regular axis to give each point an index and make the x- and y-values dependent variables.

On the other hand, if the points are not quite that irregular, but rather data were taken at each (or most) combination of x- and y-values, irregular axes may be appropriate. This would mean that the data really did form a grid.

Constraints

Component of (two-way)(inherited)

Inherited Field Elements

SE_Element_Type axis_type; (notes)
EDCS_Unit_Code value_unit; (notes)
EDCS_Scale_Code value_scale; (notes)
SE_Short_Integer_Positive axis_value_count; (notes)

Field Elements

SE_Property_Data_Value axis_value_array[];
SE_Interpolation_Type interpolation_type; (notes)

Notes

Fields Notes


axis_type

 This specifies the property being described by the given <Axis>.

value_unit

 This specifies the unit of measurement of the given <Axis>, which
 shall be compatible with the requirements imposed by axis_type.

 If axis_type does not require a unit of measurement (for example,
 if axis_type requires a value type of STRING), then value_unit
 shall be set to EUC_UNITLESS.

value_scale

 This specifies the scale applicable to value_unit.

 If axis_type does not require a unit of measurement (for example,
 if axis_type requires a value type of STRING), then value_scale
 shall be set to ESC_UNI.

axis_value_count

 This is the number of "hash marks" along the given <Axis>.

interpolation_type

 This allows the data provider to indicate how best to interpolate
 the data to points that are in-between grid points on the axis.
 When a <Data Table> has more than one axis, the order of the
 interpolations is in the order of axis definitions.
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Last updated: May 15, 2003 Copyright © 2003 SEDRIS™