pyc3dsample 0.0.5

Interface to easily deal with a C3D file, including some helpful methods for dealing with gait analysis (e.g. detecting heel strike)

PyC3DSample

Interface to easily deal with a C3D file, including some helpful methods for dealing with gait analysis (e.g. detecting heel strike)

Installation

pip install pyc3dsample

Basic usage

Initialize PyC3DSample object and get general information about C3D file by just printing the object

from pyc3dsample import PyC3DSample

Test = PyC3DSample(<path_to_c3dfile>)
print(Test)

ID          : <path_to_c3dfile>
FrameRate   : 100.0
TimeStep    : 0.01
FirstFrame  : 0
LastFrame   : 203
TotalFrames : 204

To get the progression of the left hip angles with respect to the X-axis.

Test.get_TimeProgress("LHipAngles_X")

To get events (e.g. left or right foot strike, or a general event added by the user)

# Get events -> List of (<label>, <time [s]>)
print(Test.Events)

[('Event', 0.99)]

Get progression of the left knee angles with respect to the X-axis from 100 ms before an event, until the event itself.

EventEvent = round(
    [e for e in Test.Events if e[0] == 'Event'][0][1], 2
)
print(
    Test.get_TimeProgressRange("LKneeAngles_X", EventEvent-0.1, EventEvent)
)

[[ 0.89       38.35063553]
 [ 0.9        34.10266495]
 [ 0.91       29.63624573]
 [ 0.92       25.12419128]
 [ 0.93       20.75816917]
 [ 0.94       16.72034645]
 [ 0.95       13.15703011]
 [ 0.96       10.16346359]
 [ 0.97        7.78041172]
 [ 0.98        5.99653673]
 [ 0.99        4.75045919]]

Get and plot position and velocity of the RHEE marker along the global z-axis.

RHEE_Z  = Test.get_TimeProgress("RHEE_Z")
RHEE_Zd = Test.get_TimeProgress1D("RHEE_Z")

# Plot
fig, axs = plt.subplots(2, 1, sharex=True)

# Position
axs[0].plot(RHEE_Z[:,0], RHEE_Z[:,1])
axs[0].set_ylabel("Position [mm]")
axs[0].set_title("RHEE Marker Position (z)", loc="left", fontsize="large")
# Velocity
axs[1].plot(RHEE_Zd[:,0], RHEE_Zd[:,1])
axs[1].set_ylabel("Velocity [mm/s]")
axs[1].set_xlabel("Time [s]")
axs[1].set_title("RHEE Marker Velocity (z)", loc="left", fontsize="large")
axs[0].grid()
axs[1].grid()
fig.tight_layout()
plt.show()

To identify heel strikes.

rHeelStrike_Time = Test.get_HeelStrike('R', _method='yHeelSnap')
lHeelStrike_Time = Test.get_HeelStrike('L', _method='yHeelSnap')
print(f"Right heel strike at : {rHeelStrike_Time}")
print(f"Left heel strike at  : {lHeelStrike_Time}")

Right heel strike at : [0.6, 1.61]
Left heel strike at  : [0.1, 1.09]