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--- visual3d:documentation:pipeline:metric_commands:metric_to_fit_signal_to_line [2025/10/01 18:20] – [Example Tracking Pelvis Position While Walking] wikisysop
+++ visual3d:documentation:pipeline:metric_commands:metric_to_fit_signal_to_line [2025/10/01 19:32] (current) – [Example: Comparing Linearity of Two or More Signals:] wikisysop
@@ Line 96: / Line 96: @@
 The R^2 statistic indicates how closely the linear equation models the dataset. The closer the R^2 value is to 1 the more linear of a relationship present in the data. Here the pelvis cg position follows an almost perfectly linear trajectory.
+====Example: Comparing Linearity of Two or More Signals:====
+Here we use **Metric To Fit Signal To Line** to compute and compare the R^2 value of two joint signals between events and plot corresponding linear equation for each. In this example the command is used to compare the position of the distal (knee end) and proximal (hip end) ends of the thigh in the direction of progression for a running trial. We will use **Metric To Fit Signal To Line** to compare the linearity of the two ends of the femur. It is expected that the distal end will exhibit less linear movement as the knee joint has a greater ability for anterior/posterior translation than the hip joint which is fixed to the pelvis.
+First we will find the linear equations and associated values for each end of the RTH.
+<code>
+Metric_To_Fit_Signal_To_Line
+/RESULT_METRIC_FOLDER=PROCESSED
+/RESULT_METRIC_NAME=RTH_DIST_POS
+/SIGNAL_TYPES=KINETIC_KINEMATIC
+/SIGNAL_FOLDER=RTH
+/SIGNAL_NAMES=DistEndPos
+/SIGNAL_COMPONENTS=Y
+/X_SIGNAL_TYPE=FRAME_NUMBERS
+! /X_SIGNAL_FOLDER=ORIGINAL
+! /X_SIGNAL_NAME=TIME
+/X_SIGNAL_COMPONENT=0
+! /EVENT_SEQUENCE=
+! /EXCLUDE_EVENTS=
+! /GENERATE_MEAN_AND_STDDEV=FALSE
+! /APPEND_TO_EXISTING_VALUES=FALSE
+;
+</code>
+<code>
+Metric_To_Fit_Signal_To_Line
+/RESULT_METRIC_FOLDER=PROCESSED
+/RESULT_METRIC_NAME=RTH_PROX_POS
+/SIGNAL_TYPES=KINETIC_KINEMATIC
+/SIGNAL_FOLDER=RTH
+/SIGNAL_NAMES=ProxEndPos
+/SIGNAL_COMPONENTS=Y
+/X_SIGNAL_TYPE=FRAME_NUMBERS
+! /X_SIGNAL_FOLDER=ORIGINAL
+! /X_SIGNAL_NAME=TIME
+/X_SIGNAL_COMPONENT=0
+! /EVENT_SEQUENCE=
+! /EXCLUDE_EVENTS=
+! /GENERATE_MEAN_AND_STDDEV=FALSE
+! /APPEND_TO_EXISTING_VALUES=FALSE
+;
+</code>
+**Results**
+Distal End:
+{{:visual3d:documentation:pipeline:metric_commands:rth_dist.png?500|}}
+Proximal End:
+{{:visual3d:documentation:pipeline:metric_commands:rth_prox.png?500|}}
+The results show that both ends of the right thigh segment follow similar linear equations with almost identical slopes (item 1) and intercepts (item 2). The main difference can be seen in the R^2 value (item 6) with the proximal end of the segment more closely aligning with the linear equation (high R^2 value), as expected.
+**Graphing Equations**
+{{:visual3d:documentation:pipeline:metric_commands:dist_vs_prox.png?600|}}
+Creating a new 2D graph in the reports tab helps to visualize the metrics we just computed. Here it can be seen that the proximal end of the thigh follows an almost perfectly linear trajectory, while the distal end line almost oscillates around the proximal line showing the variance present with each stride. See [[visual3d:tutorials:reports:visualizing_data|this tutorial for more information on plotting data in Visual3d]].
 ====Notes====