Table of Contents
Metric Signal Value At Event
Overview
The Metric_Signal_Value_At_Event command provides the value of the specified signal at the specified frame of data is stored as a metric. It can be found in the Pipeline Workshop under Metric. This command is useful for recording the value of a signal at a specific moment in a sequence, like at the deepest point in a squat or foot on in a stride.
Notes:
- All components of the specified signal will be stored in the metric signal. The user also has the option to select an individual component
- If there are multiple occurrences of an EVENT, there will be multiple entries in the metric that is created.
- There is an option to calculate the mean and standard deviation for metrics that have multiple values.
- In cases where there is NO_DATA at an event, you need to specify the parameter /Retain_No_Data_Values=TRUE should you want this included in the resulting signal.
- Metric_Signal_At_Event replaced the legacy command Signal_Value_At_Event
Pipeline Command
The syntax for the function is as follows:
Metric_Signal_Value_At_Event /SIGNAL_TYPES= ! /SIGNAL_FOLDER=ORIGINAL ! /SIGNAL_NAMES= ! /RESULT_METRIC_FOLDER=PROCESSED /RESULT_METRIC_NAME= ! /APPLY_AS_SUFFIX_TO_SIGNAL_NAME=FALSE ! /SIGNAL_COMPONENTS= ! /COMPONENT_SEQUENCE= /EVENT_NAME= ! /EVENT_INSTANCE=0 ! /SCALE_FACTORS=1 ! /GENERATE_GLOBAL_MEAN_AND_STDDEV=TRUE ! /GENERATE_LOCAL_MEAN_AND_STDDEV=TRUE ! /APPEND_TO_EXISTING_VALUES=FALSE ! /GENERATE_VECTOR_LENGTH_METRIC=FALSE ! /RETAIN_NO_DATA_VALUES=FALSE ;
Command Parameters
The pipeline command parameters shown above are described in the table below:
| /Result_Metric_Name= | The name of the resulting signal. |
| /Result_Metric_Folder= | The folder that will contain the resulting signal |
| /Signal_Types= | The type of signal to be evaluated |
| /Signal_Names= | The names of the signals to be evaluated |
| /Signal_Folder= | The name of the signal folder |
| /Event_Name= | The name of the event Label. |
| /Generate_Mean_And_Stddev= | If there are multiple occurences of the Event, the metric will contain multiple values.If Selecte the mean and standard deviation for the metric values will be computed. |
| /Append_To_Existing_Values= | (True or False) If the metric exists, the new values will be appended to the metric, retaining all of the previous values. |
| /Generate_Metric_Length_Metric= | (True or False) If the metric is a vector quantity (e.g. has 3 components), compute the magnitude of the vector. |
| /Retain_No_Data_Values= | (True or False) If the result is no_data, retain the value. |
Dialog
The command can be edited in a text editor or in a dialog form. To edit in the dialog pop up form either click on the Edit button in the pipeline workshop or double-click on the pipeline command. The dialog is shown below.
The dialog box allows you to assign values to the command parameters outlined above.
Example: Find Value of a Target
This example calculates the value of the TARGET RFT1 at the Event_Label RON
Metric_Signal_Value_At_Event /Result_Metric_Name=RFT1_ON /Result_Metric_Folder=PROCESSED /Signal_Types=TARGET /Signal_Names=RFT1 /Signal_Folder=ORIGINAL /Event_Name=RON /Generate_Mean_And_Stddev=FALSE /Append_To_Existing_Values=FALSE /Generate_Metric_Length_Metric=FALSE /Retain_No_Data_Values=TRUE ;
For a single Component
Since Metric_Signal_Value_At_Event outputs all three components, here is a workaround of the previous example that will output one component. Evaluate_Expression is used to create a signal with one component, the z component for RFT1. Then the Metric_Signal_Value_At_Event will calculate the value of the TARGET RFT1 at the Event_Label RON.
! RFT1 Z component Evaluate_Expression /Expression=TARGET::ORIGINAL::RFT1::Z /Result_Name=RFT1_Z /Result_Type=DERIVED /Result_Folder=ORIGINAL ; Metric_Signal_Value_At_Event /Result_Metric_Name=RFT1_ON /Result_Metric_Folder=PROCESSED /Signal_Types=DERIVED /Signal_Names=RFT1_Z /Signal_Folder=ORIGINAL /Event_Name=RON /Generate_Mean_And_Stddev=FALSE /Append_To_Existing_Values=FALSE /Generate_Metric_Length_Metric=FALSE /Retain_No_Data_Values=TRUE ;
Example: Calculate the Time of an Event
This example calculates the time of the Event_Label RON
Metric_Signal_Value_At_Event /Result_Metric_Name=RON_TIME /Result_Metric_Folder=PROCESSED /Signal_Types=FRAME_NUMBERS /Signal_Names=TIME /Signal_Folder=ORIGINAL /Event_Name=RON /Generate_Mean_And_Stddev=FALSE /Append_To_Existing_Values=FALSE /Generate_Metric_Length_Metric=FALSE /Retain_No_Data_Values=FALSE ;
P2D Signals
Consider a P2D signal created using Global_Normalized_Signal_Mean. The resulting signal has three components, an index, a mean signals, and a standard deviation signal. It is possible to compute the maximum value of the 3 components using Metric_Maximum but it isn't possible to directly identify the standard deviation at that index because it isn't possible to define an Event for a time normalized signal (e.g.it has no frame rate or time.
Without having an event you cannot get the value of a signal at that event using Metric_Signal_Value_At_Event. One solution, albeit a non-intuitive solution is to SORT (descending) the P2D signal by the second component (eg. the MEAN).
Evaluate_Expression /EXPRESSION=SORT(P2D::TEST::LHIP_ANGLE, -1.0, 2) ! /SIGNAL_TYPES= ! /SIGNAL_FOLDER=ORIGINAL ! /SIGNAL_NAMES= /RESULT_TYPES=P2D /RESULT_FOLDERS=TEST_SORTED /RESULT_NAME=LHIP_ANGLE_SORTED !/APPLY_AS_SUFFIX_TO_SIGNAL_NAME=FALSE ;
For the resulting signal, the maximum value and the associated standard deviation will be in the first frame.