Plotting P2D Data

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Introduction

What is P2D Data?

P2D data is average normalized data that was calculated over multiple cycles or trials. Typically, P2D signals are calculated using the Global_Normalized_Signal_Mean command. The average across multiple trials will be stored in the GLOBAL workspace.

Background

To plot control data - or an average data set, you must first create the average data set. This is done by creating a P2D file. Once the P2D file has been created, you can load it into your workspace and add the data to a graph.

Usually the first element of the P2D file contains the "frame" data (plotted as the X Axis Data), the second component is the mean data (plotted as the Y Axis Data), the standard deviation is the third component (check box "Add Standard Deviation"). The standard deviation will be displayed as a shaded region on the graph.

Download

You can download the sample files here.

  • Sub01_Workspace.cmz sample subject workspace
  • Normal_Data_Individual_Right_and_Left.vnd sample control database
  • Report_Template_P2D.rgt sample report template plotting P2D data

Before you do this tutorial:

Before you complete this tutorial, you want to make sure:

  1. That you know how to create a graph
  2. That you know how to create a P2D file

Plot P2D Data

Open the CMZ File

This step is done to load the data for one subject.

  1. File -> Open
    1. Select the Sub01_Workspace.cmz file

Load the P2D Data

This loads the P2D file which contains the mean and standard deviation for multiple subjects.

  1. File -> Open
    1. Select the Normal_Data_Individual_Right_and_Left.vnd file

Note: The Workspace tab does not display the Normal Database as being open at this time. This is because the normal data is simply stored as signals in the Global Workspace. The Global signals, however, have been loaded and can be seen by selecting GLOBAL as the active file.

Quickly View the P2D Data

This step is just to familiarize yourself with the P2D file format.

In the Signals and Events tab:

  1. Set the Active File to GLOBAL
    1. Expand P2D
    2. Expand Processed
    3. Left click on the signal LAnkleAngle_X_LHS_LHS
  1. Note that the P2D signal has three components:
    1. The first component is the "frame" signal. There will one frame for each point the signal was normalized to
    2. The second component is the average signal at each frame
    3. The third component is the standard deviation at each frame

P2D QuickViewGraph.png
P2D QuickViewData.png

Plotting the P2D Data

In the Reports Tab:

  1. Add a new line to a graph
  2. Tag to Graph: GLOBAL
  3. X Axis Data
    1. Type: P2D
    2. Folder: PROCESSED
    3. Name: LAnkleAngle_X_LHS_LHS
    4. Component: 1
  4. Y Axis Data
    1. Type: P2D
    2. Folder: PROCESSED
    3. Name: LAnkleAngle_X_LHS_LHS
    4. Component: 2
    5. Check "Add Standard Deviation"
      1. Component: 3
  5. P2D Line Style: Solid
  6. P2D Color: Black
  7. Std Dev Style: Solid

P2D GraphDialog.png

If everything is correct, you should see the data for the data in the CMZ (green lines) and the average data is shown in black. The solid black line is the mean and the gray band is the standard deviation.

P2D 2DGraph.png

NOTE: If you open the Report_Template_P2D.rgt report template, you will notice that the P2D signals were plotted for the first page.

Computing a Time Normalized Average Event

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