Importing ordered or structured tabular data from a text file

Certain tabular data has an inherent order or structure. For example, certain tabular data that has an independent domain that consists of two spatial variables might possess an inherent row-column structure when you plot it against Cartesian axes.

When the tabular data has an inherent order or structure, and the tabular data is organized in the text file to reflect the order or structure, depending on the independent domain of the tabular data, you may be able to do the following:

• Parameterize the independent domain of the tabular data.

• Improve the computational efficiency of table lookup.

• Improve the accuracy of table lookup.

• Reduce the memory required to store the tabular data.

Tabular data with a single independent variable

If the tabular data has an independent domain that consists of a single spatial variable and the tabular data is ordered in ascending or descending order in the text file, the software can transform the spatial variable from the physical coordinate to a parametric coordinate when it imports the text file.

For more information, see Importing tabular data as a parametric line.

Tabular data with two independent variables

If the tabular data has an independent domain that consists of two spatial variables, the tabular data is ordered in the text file to reflect an inherent row-column structure in the data, and you specify the number of rows and columns in the data, the software can transform the spatial variables from physical coordinates to parametric coordinates when it imports the text file.

The benefits of creating a parametric representation of the tabular data are as follows:

• Because the spatial domain of the table field you create is parametric, you can apply the table field to other four-sided surfaces.

• When you use Delaunay interpolation, the software creates triangles only within the bounds of the four-sided surface. If you do not transform from physical coordinates to parametric coordinates, and the surface has concave edges, the software creates triangles outside the four-sided surface.

For more information, see Importing tabular data as a parametric plane.

If the tabular data has an independent domain that contains one or two non-spatial variables, the option to parameterize the tabular data does not exist. However, if the tabular data is ordered in the text file to reflect an inherent row-column structure in the data, you specify the number of rows and columns in the data, and you select a Delaunay interpolation option, the software automatically uses the structure of the data to improve the computational efficiency and accuracy of table lookup.

• Because of the inherent row-column structure of the data, the software can efficiently create a quadrilateral mesh from which it performs the table lookup.

• Because the table lookup uses the values at the four data points surrounding a lookup point, the accuracy of the table lookup is typically better than the table lookup from a triangular mesh.Note: If the tabular data is parameterized when it is imported from the text file and you select a Delaunay interpolation option, the software creates a Delaunay triangulation of the tabular data points. Thus, the table lookup is based on the values at the three data points surrounding the lookup point only.

Tabular data with three independent variables

If the tabular data has an independent domain that consists of three variables, the tabular data is ordered in the text file to reflect layers of row-column structure data, you specify the number of rows, columns, and layers in the data, and you select a Delaunay interpolation option, the software automatically uses the structure of the data to improve the computational efficiency and accuracy of the table lookup.

• Because of the inherent layered, row-column structure of the data, the software can efficiently create a hexahedron mesh from which it performs the table lookup.

• Because the table lookup uses the values at the eight data points surrounding a lookup point, the accuracy of the table lookup is typically better than the table lookup from a tetrahedron mesh which uses the values at the four data points surrounding the lookup point only.Note: If the software does not recognize a layered, row-column structure in the data and you select a Delaunay interpolation option, the software creates a Delaunay tetrahedralization of the tabular data points. Thus, the table lookup is based on the values at the four data points surrounding the lookup point only.

Structured tabular data

Structured tabular data can have spatial and non-spatial independent variables. The software considers tabular data with two independent variables structured if the inherent row-column structure of the tabular data forms a lattice of rectangles.

For example, the following tabular data with two independent variables is structured:

Structured tabular data having two independent variables x and y

Data point	x	y
1	2.00	2.00
2	3.20	2.00
3	4.80	2.00
4	2.00	3.00
5	3.20	3.00
6	4.80	3.00
7	2.00	6.00
8	3.20	6.00
9	4.80	6.00

Each increment in the X-direction repeats for each Y-coordinate, and each increment in the Y-direction repeats for each X-coordinate. Thus, if you create a Cartesian plot of the data points, they form a lattice of rectangles.

When the software detects that row-column structured data is structured, to minimize storage requirements, it automatically uses a condensed format to store the tabular data.

For example, the software only needs to store one repetition of the X-coordinates, one repetition of the Y-coordinates, and the values of the dependent variable at each data point.

For table fields with many data points, the amount of memory required to store the tabular data may be significantly reduced.

The software considers tabular data with three independent variables structured if the layered, row-column structure of the tabular data forms a lattice of rectangular parallelepipeds.

For example, the following tabular data with three independent variables is structured:

Structured tabular data having three independent variables x, y, and z

Data point	x	y	z
1	2.00	2.00	1.00
2	3.20	2.00	1.00
3	4.80	2.00	1.00
4	2.00	3.00	1.00
5	3.20	3.00	1.00
6	4.80	3.00	1.00
7	2.00	6.00	1.00
8	3.20	6.00	1.00
9	4.80	6.00	1.00
10	2.00	2.00	3.50
11	3.20	2.00	3.50
12	4.80	2.00	3.50
13	2.00	3.00	3.50
14	3.20	3.00	3.50
15	4.80	3.00	3.50
16	2.00	6.00	3.50
17	3.20	6.00	3.50
18	4.80	6.00	3.50
19	2.00	2.00	5.00
20	3.20	2.00	5.00
21	4.80	2.00	5.00
22	2.00	3.00	5.00
23	3.20	3.00	5.00
24	4.80	3.00	5.00
25	2.00	6.00	5.00
26	3.20	6.00	5.00
27	4.80	6.00	5.00

Similar to the two independent variable case, when the software detects that layered, row-column structured data is structured, to minimize storage requirements, it automatically uses a condensed format to store the tabular data.

Where do I find it?

Application	Pre/Post
Prerequisites	A text file with ordered or structured tabular data
Simulation Navigator	Right-click the Fields node→New Field→Table
Location in dialog box	Table Field dialog box→Definition page→Import from Text File

Learn more

Importing tabular data as a parametric line

Importing tabular data as a parametric plane

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Importing ordered or structured tabular data from a text file, Simcenter 3D 2021.1 Series

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