Viewing functional data

Functional data

Functional data is data whose value varies with some parameter(s). For example, many material properties vary with temperature; the cost of a manufacturing process, per unit, may vary with the total number of units that are made, the material cost, the component mass, and the overhead rate. Functional data may be displayed on a datasheet in various forms. For example:

• As a value evaluated at fixed parameter values (for data based on an equation):

• As a graph showing a multi-linear interpolation of the source data:
  
• As a table of data values:
  

Viewing functional data graphs

To view a functional data graph in the datasheet, click  View this data or View Graph.

You can zoom in on sections of the graph and read off values with the mouse. Click to view an example.

Using the commands below the graph, you can:

• Click Add to Comparison Chart to add the graph to a comparison chart, enabling you to compare curves from different records.
• Click Copy to copy the graph image and legend to the clipboard, for example, for use in a document, spreadsheet or presentation.

For data that is based on an equation, you can change the graph title and/or the axis properties by clicking Graph Tools. For other types of functional data, Graph Tools opens a page where you can look at the underlying graph data in more detail.

• To view the underlying data values as a table instead of as a graph, click View All Data. (You can also do this by clicking Show graph on the View menu at the top of the page).
• Click Add to Comparison Chart to add the graph to a comparison chart, enabling you to compare curves from different records.
• Click Save as CSV to save the underlying graph data to a CSV file, which can then be opened in Microsoft Excel.
• Click Copy Data to Clipboard to copy the graph data to the clipboard. Depending on your browser, you may then need to use your browser's Copy function to copy the data to the clipboard from the Copy to Clipboard window.
• For some types of data, you may also be able to change the X-axis of the graph, and interpolate a y-axis value from specified parameter values.

Click View>Show high-res graph to view the graph in a new browser tab/window, allowing you to view it in higher resolution, and to print the graph, parameter settings and metadata.

Viewing functional data tables

To view a functional data table in the datasheet, click View this data or View Table.

Quality ratings for each data point will be shown in a column, if available. Click View The Data to display the table in its own view, where you can:

• Click on a column heading to sort the table by the selected column.
• Click Save as CSV to save the data to a CSV file.
• Click Copy to Clipboard to copy the data to the clipboard. Depending on your browser, you may then need to use your browser's Copy function to copy the data to the clipboard from the Copy to Clipboard window.

For some types of data, you can also interpolate a y-axis value from a specified parameter value in this data view.

Working with equation-based data

For data values based on an equation, you can explore the effect of changing the parameter values used to calculate the equation and adding curves to the graph; note that this does not change any data in the database, just the display in the current session. You can also view a table of the data points, and change the graph axes.

To change the parameter values used to calculate the equation

1. On the datasheet, click Parameters below the attribute name.
2. In the first row, enter a value or choose a value from the list (for discrete attributes). Only the first row is used to evaluate the equation; other rows are used for plotting only.

3. Click Save.

To add a curve to the graph

1. On the datasheet, click Parameters below the attribute name.
2. Click Add new curve and choose a value from the drop down list, or enter a value.
3. Click Save.

To view the data points

Click View The Data below the graph to view a table of the data points calculated at a specified number of points along the curve. Click to show an example  

On this page you can:

• Specify how many points you want to see in the table by changing the number in the Number of rows per curve box.
• View the calculated parameter (X-axis) value corresponding to a given Y-axis value: in the Parameter value calculator section, enter the Y-axis value of interest, then click Go. A table appears showing the calculated (X-axis) value on each curve for the specified value.

To change the graph axis properties

1. Click Graph Tools below the graph.
2. To change the parameter plotted on the X-axis, choose a different parameter from the list.
3. For curve data, you can
   • Transpose the axes.
   • For each axis, set the axis title, maximum and minimum value, and scale (linear or logarithmic).
4. Click Save.

Parameter ordering for grid functional data

The order of parameters associated with functional data is important in some cases. Specifically, if you are using grid functional data where one or more of the parameters use cubic spline interpolation, then parameter order may have an effect on the interpolation results. Note that parameter order has no effect if only linear interpolation is being used, or in series functional data.

Parameter order is important because gridded graphs are interpolated one parameter at a time. So, for a graph with 3 parameters (strain, cycles and time), to interpolate to a single point:

1. We first constrain a parameter (strain = 0.1%, say) and create a new graph that only has the parameters cycles and time.
2. Then we constrain another parameter (cycles = 1,000,000, say) to get a graph that only has one parameter.
3. Finally, we constrain the last parameter (time) to get a point value.

If we use a non-linear interpolation strategy for one of those steps, the value of the interpolated point can vary depending upon the order in which we interpolate the parameters.

Note that each piece of functional data can have the parameters stored in a different order. If version control is being used, then each version of the data can have a different order.

The order of parameters on functional data is set when you view the data in MI:Viewer, or when data is imported by the Excel or Text importer. In MI:Viewer, the order of the parameters is controlled by the order of the parameter columns. Grid functional data has the following format:

In this example, Parameter 1 will be first, followed by Parameter 2, etc.

It is possible to check the order of parameters by using the View All Data option in Graph Tools. The order that the parameters appear in the columns is the order they are stored in the functional data.