Python modules¶
Rationale¶
This is an attempt to make analysis of wheelchair biomechanics data more accessible and transparent. Previously all analyses were performed with commercial software that is not available to everyone, especially to people not associated with a university. Having the analysis in Python makes it accessible and more readable (hopefully) for everyone. By sharing the code I hope to be transparent and to reduce the amount of times this code has to be written by other people.
Examples & audience¶
People working in our lab that want to work with data from any of our instruments. It can, of course, also be used by other people, provided that you have similar equipment. Most of the time you will only need one or two functions which you can just take from the source code or you can just install the package as it has very little overhead anyways and only uses packages that you probably already have installed. Also have a look at the examples.
Installation¶
Option 1: the package is now on pip:
pip install worklab
Option 2: download the package from this page, and run:
python setup.py install
Option 3: don’t install it and just include the scripts in your working directory (why though?).
To verify if everything works simply try to import worklab:
python
import worklab as wl
That’s it.
Breakdown¶
com: Provides functions for reading and writing data, use
load
to infer filetype and automatically read it. If you use a different naming scheme you can always call the specific load functions.kinetics: Contains all essentials for measurement wheel and ergometer data. You only need the toplevel function
auto_process
for most usecases.move: Contains kinematics and movement related functions for NGIMU and some functions for 3D kinematics.
physio: Contains physiological calculations, which for now is basically nothing as the spirometer does everything for you. Might include EMG and the likes later though.
plots: Contains some basic plotting functionalities for plots that become repetitive, needs some TLC to become really useful.
utils: Contains all functions that are useful for more than one application (e.g. filtering and interpolation).
The return of a function is a Pandas DataFrame in 9/10 cases. This means that you can also use all Pandas goodness.
Communication (.com)¶
Contains functions for reading data from any worklab device. If you abide by regular naming conventions you will only need the load function which will infer the correct function for you. You can also use devicespecific load functions if needed.
load¶

worklab.com.
load
(filename='')[source]¶ Attempt to load a common data format.
Most important function in the module. Provides high level loading function to load common data formats. If no filename is given will try to load filename using a file dialog. Will try to infer data source from filename. Try to use a specific load function if load cannot infer the datatype.
 Parameters
filename (str) – name or path to file of interest
 Returns
data – raw data, format depends on source, but is usually a dict or pandas DataFrame
 Return type
pd.DataFrame
See also
load_bike()
,load_esseda()
,load_hsb()
,load_n3d()
,load_opti()
,load_optitrack()
,load_imu()
,load_spiro()
,load_spline()
,load_sw()
,load_opti_offset()
load_bike¶

worklab.com.
load_bike
(filename)[source]¶ Load bicycle ergometer data from LEM datafile.
Loads bicycle ergometer data from LEM to a pandas DataFrame containing time, load, rpm, and heart rate (HR).
 Parameters
filename (str) – full file path or file in existing path from LEM Excel sheet (.xls)
 Returns
data – DataFrame with time, load, rpm, and HR data
 Return type
pd.DataFrame
load_esseda¶

worklab.com.
load_esseda
(filename)[source]¶ Loads HSB ergometer data from LEM datafile.
Loads ergometer data measured with LEM and returns the data in a dictionary for the left and right module with a DataFrame each that contains time, force (on wheel), and speed.
 Parameters
filename (str) – full file path or file in existing path from LEM Excel sheet (.xls)
 Returns
data – dictionary with DataFrame for left and right module
 Return type
dict
See also
load_wheelchair()
Load wheelchair information from LEM datafile.
load_spline()
Load calibration splines from LEM datafile.
load_wheelchair¶

worklab.com.
load_wheelchair
(filename)[source]¶ Loads wheelchair from LEM datafile.
Loads the wheelchair data from a LEM datafile. Note that LEM only recently added this to their exports. Returns:
Column
Data
Unit
name
chair name
rimsize
radius of handrim
m
wheelsize
radius of the wheel
m
weight
weight of the chair
kg
 Parameters
filename (str) – full file path or file in existing path from LEM Excel sheet (.xls)
 Returns
wheelchair – dictionary with wheelchair information
 Return type
dict
See also
load_esseda()
Load HSB data from LEM datafile.
load_spline()
Load calibration splines from LEM datafile.
load_hsb¶

worklab.com.
load_hsb
(filename)[source]¶ Loads HSB ergometer data from HSB datafile.
Loads ergometer data measured with the HSBlogger2 and returns the data in a dictionary for the left and right module with a DataFrame each that contains time, force, and speed. HSB files are generally only for troubleshooting and testing that is beyond the scope of LEM.
 Parameters
filename (str) – full file path or file in existing path from HSB .csv file
 Returns
data – dictionary with DataFrame for left and right module
 Return type
dict
load_n3d¶

worklab.com.
load_n3d
(filename, verbose=True)[source]¶ Reads NDIOptotrak data files
 Parameters
filename (str) – Optotrak data file (.n3d)
verbose (bool) – Print some information about the data from the file. If True (default) it prints the information.
 Returns
optodata – Multidimensional numpy array with marker positions (in m) in sample x xyz x marker dimensions.
 Return type
ndarray
load_opti¶

worklab.com.
load_opti
(filename, rotate=True)[source]¶ Loads Optipush data from .data file.
Loads Optipush data to a pandas DataFrame, converts angle to radians, and flips torque (Tz). Returns a DataFrame with:
Column
Data
Unit
time
sample time
s
fx
force on local xaxis
N
fy
force on local yaxis
N
fz
force on local zaxis
N
mx
torque around xaxis
Nm
my
torque around yaxis
Nm
torque
torque around zaxis
Nm
angle
unwrapped wheel angle
rad
Note
Optipush uses a local coordinate system, option to rotate Fx and Fy available in >1.6
 Parameters
filename (str) – filename or path to Optipush .data (.csv) file
rotate (bool) – whether or not to rotate from a local rotating axis system to a global nonrotating one, default is True
 Returns
opti_df – Raw Optipush data in a pandas DataFrame
 Return type
pd.DataFrame
See also
load_sw()
Load measurement wheel data from a SMARTwheel
load_optitrack¶

worklab.com.
load_optitrack
(filename, include_header=False)[source]¶ Loads Optitrack marker data.
 Parameters
filename (str) – full path to filename or filename in current path
include_header (bool) – whether or not to include the header in the output default is False
 Returns
marker_data – Marker data in dictionary, metadata in dictionary
 Return type
dict
load_imu¶

worklab.com.
load_imu
(root_dir, filenames=None)[source]¶ Imports NGIMU session in nested dictionary with all devices and sensors.
Import NGIMU session in nested dictionary with all devices with all sensors. Translated from xioTechnologies 1.
 Parameters
root_dir (str) – directory where session is located
filenames (list, optional) – list of sensor names or single sensor name that you would like to include, only loads sensor if not specified
 Returns
session_data – returns nested object sensordata[device][sensor][dataframe]
 Return type
dict
References
load_spiro¶

worklab.com.
load_spiro
(filename)[source]¶ Loads COSMED spirometer data from Excel file.
Loads spirometer data to a pandas DataFrame, converts time to seconds (not datetime), computes energy expenditure, computes weights from the time difference between samples, if no heart rate data is available it fills the column with np.NaNs. Returns a DataFrame with:
Column
Data  Unit
time
time at breath
s
HR
heart rate
bpm
EE
energy expenditure
J/s
RER
exchange ratio
VCO2/VO2
VO2
oxygen
l/min
VCO2
carbon dioxide
l/min
VE
ventilation
l/min
VE/VO2
ratio VE/VO2 
VE/VCO2
ratio VE/VCO2
O2pulse
oxygen pulse (VO2/HR)
PetO2
end expiratory O2 tension
mmHg
PetCO2
end expiratory CO2 tension
mmHg
VT
tidal volume
l
weights
sample weight
 Parameters
filename (str) – full file path or file in existing path from COSMED spirometer
 Returns
data – Spirometer data in pandas DataFrame
 Return type
pd.DataFrame
load_spline¶

worklab.com.
load_spline
(filename)[source]¶ Load wheelchair ergometer calibration spline from LEM datafile.
Loads Esseda calibration spline from LEM which includes all forces (at the roller) at the different calibration points (1:10:1 km/h).
 Parameters
filename (object) – full file path or file in existing path from LEM excel file
 Returns
data – left and right calibration values
 Return type
dict
load_sw¶

worklab.com.
load_sw
(filename, sfreq=200)[source]¶ Loads SMARTwheel data from .txt file.
Loads SMARTwheel data to a pandas DataFrame, converts angle to radians and unwraps it. Returns a DataFrame with:
Column
Data
Unit
time
sample time
s
fx
force on global xaxis
N
fy
force on global yaxis
N
fz
force on global zaxis
N
mx
torque around xaxis
Nm
my
torque around yaxis
Nm
torque
torque around zaxis
Nm
angle
unwrapped wheel angle
rad
Note
SMARTwheel uses a global coordinate system
 Parameters
filename (str) – filename or path to SMARTwheel .data (.csv) file
sfreq (int) – sample frequency of SMARTwheel, default is 200Hz
 Returns
sw_df – Raw SMARTwheel data in a pandas DataFrame
 Return type
pd.DataFrame
See also
load_opti()
Load measurement wheel data from an Optipush wheel.
Kinetics (.kin)¶
Contains functions for working with measurement wheel (Optipush and SMARTwheel) and ergometer (Esseda) data
You will usually only need the toplevel function auto_process
.
auto_process¶

worklab.kin.
auto_process
(data, wheelsize=0.31, rimsize=0.27, sfreq=200, co_f=15, ord_f=2, co_s=6, ord_s=2, force=True, speed=True, variable='torque', cutoff=0.0, wl=201, ord_a=2, minpeak=5.0)[source]¶ Top level processing function that performs all processing steps for mw/ergo data.
Contains all signal processing steps in fixed order. It is advised to use this function for all (pre)processing. If needed take a look at a specific function to see how it works.
 Parameters
data (pd.DataFrame, dict) – raw ergometer or measurement wheel data
wheelsize (float) – wheel radius [m]
rimsize (float) – handrim radius [m]
sfreq (int) – sample frequency [Hz]
co_f (int) – cutoff frequency force filter [Hz]
ord_f (int) – order force filter [..]
co_s (int) – cutoff frequency force filter [Hz]
ord_s (int) – order speed filter [..]
force (bool) – force filter toggle, default is True
speed (bool) – speed filter toggle, default is True
variable (str) – variable name used for peak (push) detection
cutoff (float) – noise level for peak (push) detection
wl (float) – window length angle filter
ord_a (int) – order angle filter [..]
minpeak (float) – min peak height for peak (push) detection
 Returns
data (pd.DataFrame, dict)
pushes (pd.DataFrame, dict)
filter_mw¶

worklab.kin.
filter_mw
(data, sfreq=200.0, co_f=15.0, ord_f=2, wl=201, ord_a=2, force=True, speed=True)[source]¶ Filters measurement wheel data.
Filters raw measurement wheel data. Should be used before further processing.
 Parameters
data (pd.DataFrame) – raw measurement wheel data
sfreq (float) – sample frequency [Hz]
co_f (float) – cutoff frequency force filter [Hz]
ord_f (int) – order force filter [..]
wl (float) – window length angle filter
ord_a (int) – order angle filter [..]
force (bool) – force filter toggle, default is True
speed (bool) – speed filter toggle, default is True
 Returns
data (pd.DataFrame)
Same data but filtered.
See also
filter_ergo¶

worklab.kin.
filter_ergo
(data, co_f=15.0, ord_f=2, co_s=6.0, ord_s=2, force=True, speed=True)[source]¶ Filters ergometer data.
Filters raw ergometer data. Should be used before further processing.
 Parameters
data (dict) – raw measurement wheel data
co_f (float) – cutoff frequency force filter [Hz]
ord_f (int) – order force filter [..]
co_s (float) – cutoff frequency speed filter [Hz]
ord_s (int) – order speed filter [..]
force (bool) – force filter toggle, default is True
speed (bool) – speed filter toggle, default is True
 Returns
data – Same data but filtered.
 Return type
dict
See also
process_mw¶

worklab.kin.
process_mw
(data, wheelsize=0.31, rimsize=0.275, sfreq=200)[source]¶ Basic processing for measurement wheel data.
Basic processing for measurement wheel data (e.g. speed to distance). Should be performed after filtering. Added columns:
Column
Data
Unit
aspeed
angular velocity
rad/s
speed
velocity
m/s
dist
cumulative distance
m
acc
acceleration
m/s^2
ftot
total combined force
N
uforce
effective force
N
force
force on wheel
N
power
power
W
work
instantanious work
J
 Parameters
data (pd.DataFrame) – raw measurement wheel data
wheelsize (float) – wheel radius [m]
rimsize (float) – handrim radius [m]
sfreq (int) – sample frequency [Hz]
 Returns
data
 Return type
pd.DataFrame
See also
process_ergo¶

worklab.kin.
process_ergo
(data, wheelsize=0.31, rimsize=0.275)[source]¶ Basic processing for ergometer data.
Basic processing for ergometer data (e.g. speed to distance). Should be performed after filtering. Added columns:
Column
Data
Unit
angle
angle
rad
aspeed
angular velocity
rad/s
acc
acceleration
m/s^2
dist
cumulative distance
m
power
power
W
work
instantanious work
J
uforce
effective force
N
torque
torque around wheel
Nm
Note
the force column contains force on the wheels, uforce (user force) is force on the handrim
 Parameters
data (dict) – raw ergometer data
wheelsize (float) – wheel radius [m]
rimsize (float) – handrim radius [m]
 Returns
data
 Return type
dict
See also
push_by_push_mw¶

worklab.kin.
push_by_push_mw
(data, variable='torque', cutoff=0.0, minpeak=5.0, mindist=5, verbose=True)[source]¶ Pushbypush analysis for measurement wheel data.
Push detection and pushbypush analysis for measurement wheel data. Returns a pandas DataFrame with:
Column
Data
Unit
start/stop/peak
respective indices
tstart/tstop/tpeak
respective samples
s
cangle
contact angle
rad
cangle_deg
contact angle
degrees
mean/maxpower
power per push
W
mean/maxtorque
torque per push
Nm
mean/maxforce
force per push
N
mean/maxuforce
(rim) force per push
N
mean/maxfeff
feffective per push
%
mean/maxftot
ftotal per push
N
work
work per push
J
cwork
work per cycle
J
negwork
negative work/cycle
J
slope
slope onset to peak
Nm/s
smoothness
mean/peak force
ptime
push time
s
ctime
cycle time
s
reltime
relative push/cycle
%
 Parameters
data (pd.DataFrame) – measurement wheel DataFrame
variable (str) – variable name used for peak (push) detection
cutoff (float) – noise level for peak (push) detection
minpeak (float) – min peak height for peak (push) detection
 Returns
pbp – pushbypush DataFrame
 Return type
pd.DataFrame
push_by_push_ergo¶

worklab.kin.
push_by_push_ergo
(data, variable='power', cutoff=0.0, minpeak=50.0, mindist=5, verbose=True)[source]¶ Pushbypush analysis for wheelchair ergometer data.
Push detection and pushbypush analysis for ergometer data. Returns a pandas DataFrame with:
Column
Data
Unit
start/stop/peak
respective indices
tstart/tstop/tpeak
respective samples
s
cangle
contact angle
rad
cangle_deg
contact angle
degrees
mean/maxpower
power per push
W
mean/maxtorque
torque per push
Nm
mean/maxforce
force per push
N
mean/maxuforce
(rim) force per push
N
work
work per push
J
cwork
work per cycle
J
negwork
negative work/cycle
J
slope
slope onset to peak
Nm/s
smoothness
mean/peak force
ptime
push time
s
ctime
cycle time
s
reltime
relative push/cycle
%
 Parameters
data (dict) – wheelchair ergometer dictionary
variable (str) – variable name used for peak (push) detection, default = power
cutoff (float) – noise level for peak (push) detection, default = 0
minpeak (float) – min peak height for peak (push) detection, default = 50.0
mindist (int) – minimum sample distance between peak candidates, can be used to speed up algorithm
 Returns
pbp – dictionary with left, right and mean pushbypush DataFrame
 Return type
dict
Kinematics (.move)¶
Basic functions for movement related data from optical tracking systems. If I have the time I will make a vector3d class. Most functions assume an [n, 3] or [1, 3] array or dataframe.
get_perp_vector¶

worklab.move.
get_perp_vector
(vector2d, clockwise=True, normalized=True)[source]¶ Get the vector perpendicular to the input vector. Only works in 2D as 3D has infinite solutions.
 Parameters
vector2d (np.array) – [n, 3] vector data, only uses x and y
clockwise (bool) – clockwise or counterclockwise rotation
normalized (bool) – whether or not to normalize the result, default is True
 Returns
perp_vector2d – rotated vector
 Return type
np.array
get_rotation_matrix¶

worklab.move.
get_rotation_matrix
(new_frame, local_to_world=True)[source]¶ Get the rotation matrix between a new reference frame and the global reference frame or the other way around.
 Parameters
new_frame (np.array) – [3, 3] array specifying the new reference frame
local_to_world (bool) – global to local or local to global
 Returns
rotation_matrix – rotation matrix that can be used to rotate marker data, e.g.: rotation_matrix @ marker
 Return type
np.array
get_orthonormal_frame¶

worklab.move.
get_orthonormal_frame
(point1, point2, point3, mean=False)[source]¶ Returns an orthonormal frame from three reference points. For example, a local coordinate system from three marker points.
 Parameters
point1 (np.array) – first marker point, used as origin if mean=False
point2 (np.array) – second marker point, used as xaxis
point3 (np.array) – third marker point
mean (bool) – whether or not the mean should be used as origin, default is False
 Returns
origin (np.array) – xyz column vector with coordinates of the origin which is point1 or the mean of all points
orthonormal (np.array) – 3x3 array with orthonormal coordinates [x, y, z] of the new axis system
mirror¶
rotate¶

worklab.move.
rotate
(vector3d, angle, deg=False, axis='z')[source]¶ Rotate a vector around a single given axis, specify rotation angle in radians or degrees.
 Parameters
vector3d (np.array) – vector to be rotated, also works on dataframes, assumes [n, xyz] data
angle (float) – angle to rotate over
deg (bool) – True if angle is specified in degrees, False for radians
axis (str) – axis to rotate over, default = “z”
 Returns
vector3d – rotated vector
 Return type
np.array
scale¶

worklab.move.
scale
(vector3d, x=1.0, y=1.0, z=1.0)[source]¶ Scale a vector in different directions.
 Parameters
vector3d (np.array) – array to be scaled, also works on dataframes, assumes [n, xyz] data
x (float) – xaxis scaling
y (float) – yaxis scaling
z (floag) – zaxis scaling
 Returns
vector3d – scaled array
 Return type
np.array
magnitude¶
normalize¶
distance¶

worklab.move.
distance
(point1, point2)[source]¶ Compute Euclidean distance between two points, this is the distance if you were to draw a straight line.
 Parameters
point1 (np.array) – a [1, 3] or [n, 3] array with point coordinates
point2 (np.array) – a [1, 3] or [n, 3] array with point coordinates
 Returns
distance – distance from point1 to point2 in a [1, 3] or [n, 3] array
 Return type
np.array
marker_angles¶

worklab.move.
marker_angles
(v_1, v_2, deg=False)[source]¶ Calculates n angles between two [n, 3] markers, two [1, 3] markers, or one [n, 3] and one [1, 3] marker.
 Parameters
v_1 (np.array) – [n, 3] array or DataFrame for marker 1
v_2 (np.array) – [n, 3] array or DataFrame for marker 2
deg (bool) – return radians or degrees, default is radians
 Returns
x – returns [n, 1] array with the angle for each sample or scalar value
 Return type
np.array
IMU (.imu)¶
Basic functions for movement related data from IMUs. IMU functions are specifically made for the NGIMUs we use in the worklab.
resample_imu¶

worklab.imu.
resample_imu
(sessiondata, sfreq=400.0)[source]¶ Resample all devices and sensors to new sample frequency.
Resamples all devices and sensors to new sample frequency. Sample intervals are not fixed with NGIMU’s so resampling before further analysis is recommended. Translated from xioTechnologies 2.
 Parameters
sessiondata (dict) – original session data structure to be resampled
sfreq (float) – new intended sample frequency
 Returns
sessiondata – resampled session data structure
 Return type
dict
References
calc_wheelspeed¶

worklab.imu.
process_imu
(sessiondata, camber=15, wsize=0.31, wbase=0.6, inplace=False)[source]¶ Calculate wheelchair kinematic variables based on NGIMU data
 Parameters
sessiondata (dict) – original sessiondata structure
camber (float) – camber angle in degrees
wsize (float) – radius of the wheels
wbase (float) – width of wheelbase
inplace (bool) – performs operation inplace
 Returns
sessiondata – sessiondata structure with processed data
 Return type
dict
change_imu_orientation¶

worklab.imu.
change_imu_orientation
(sessiondata, inplace=False)[source]¶ Changes IMU orientation from inwheel to onwheel
 Parameters
sessiondata (dict) – original sessiondata structure
inplace (bool) – perform operation inplace
 Returns
sessiondata – sessiondata with reoriented gyroscope data
 Return type
dict
push_imu¶

worklab.imu.
push_imu
(acceleration, sfreq=400.0)[source]¶ Push detection based on velocity signal of IMU on a wheelchair 3.
 Parameters
acceleration (np.array, pd.Series) – acceleration data structure
sfreq (float) – sampling frequency
 Returns
 Return type
push_idx, acc_filt, n_pushes, cycle_time, push_freq
References
 3
van der Slikke, R., Berger, M., Bregman, D., & Veeger, D. (2016). Push characteristics in wheelchair court sport sprinting. Procedia engineering, 147, 730734.
butterfly¶
spider¶
sprint_10m¶
sprint_20m¶
vel_zones¶
Physiology (.physio)¶
Basics for working with physiological data. We only have a spirometer in the lab at the moment and this involves very little processing. Might expand with EMG related function at some point in the future.
get_spirometer_units¶
Plotting (.plots)¶
Most variables can easily be plotted with matplotlib or pandas as most data in this package is contained in dataframes. Some plotting is tedious however and these are functions for those plots.
plot_pushes¶

worklab.plots.
plot_pushes
(data, pushes, var='torque', start=True, stop=True, peak=True, ax=None)[source]¶ Plot pushes from measurement wheel or ergometer data.
 Parameters
data (pd.DataFrame) –
pushes (pd.DataFrame) –
var (str) – variable to plot, default is torque
start (bool) – plot push starts, default is True
stop (bool) – plot push stops, default is True
peak (bool) – plot push peaks, default is True
ax (axis object) – Axis to plot on, you can add your own or it will make a new one.
 Returns
ax
 Return type
axis object
plot_pushes_ergo¶

worklab.plots.
plot_pushes_ergo
(data, pushes, title=None, var='power', start=True, stop=True, peak=True)[source]¶ Plot left, right and mean side ergometer push data
 Parameters
data (dict) – processed ergometer data dictionary with dataframes
pushes (dict) – processed push_by_push ergometer data dictionary with dataframes
title (str) – title of the plot, optional
var (str) – variable to plot, default is power
start (bool) – plot push starts, default is True
stop (bool) – plot push stops, default is True
peak (bool) – plot push peaks, default is True
 Returns
axes – an array containing an axis for the left, right and mean side
 Return type
np.array
plot_power_speed_dist¶

worklab.plots.
plot_power_speed_dist
(data, title='', ylim_power=None, ylim_speed=None, ylim_distance=None)[source]¶ Plot power, speed and distance versus time for left (solid line) and right (dotted line) seperately
Figure scales automatically, unless you specify it manually with the ylim_* arguments
 Parameters
data (dict) – processed ergometer data dictionary with dataframes
title (str) – a title for the plot
ylim_power (list [min, max] of float or int, optional) – list of the minimal and maximal ylim for power in W
ylim_speed (list [min, max] of floats or int, optional) – list of the minimal and maximal ylim for speed in km/h
ylim_distance (list [min, max] of floats or int, optional) – list of the minimal and maximal ylim for distance in m
 Returns
fig (matplotlib.figure.Figure)
axes (tuple) – the three axes objects
acc_peak_dist_plot¶

worklab.plots.
acc_peak_dist_plot
(time, acc, dist, name='')[source]¶ Plot acceleration and distance versus time, with acc_peak
 Parameters
time (np.array, pd.Series) – time structure
acc (np.array, pd.Series) – acceleration structure
dist (np.array, pd.Series) – distance structure
name (str) – name of a session
 Returns
ax
 Return type
axis object
acc_peak_plot¶
acc_plot¶
imu_push_plot¶
rot_vel_plot¶
set_axes_equal_3d¶
vel_peak_dist_plot¶

worklab.plots.
vel_peak_dist_plot
(time, vel, dist, name='')[source]¶ Plot velocity and distance against time
 Parameters
time (np.array, pd.Series) – time structure
vel (np.array, pd.Series) – velocity structure
dist (np.array, pd.Series) – distance structure
name (str) – name of a session
 Returns
ax
 Return type
axis object
vel_peak_plot¶
Utilities (.utils)¶
This module contains utility functions used by all modules or functions that have multiple applications such as filtering, finding zerocrossings, finding the nearest value in a signal.
pick_file¶
pick_files¶
pick_directory¶
pick_save_file¶
calc_weighted_average¶
make_calibration_spline¶

worklab.utils.
make_calibration_spline
(calibration_points)[source]¶ Makes a pre1.0.4 calibration spline for the Esseda wheelchair ergometer.
 Parameters
calibration_points (dict) – dict with left: np.array, right: np.array
 Returns
spl_line – dict with left: np.array, right: np.array containing the interpolated splines
 Return type
dict
make_linear_calibration_spline¶

worklab.utils.
make_linear_calibration_spline
(calibration_points)[source]¶ Makes a post1.0.4 calibration spline for the Esseda wheelchair ergometer.
 Parameters
calibration_points (dict) – dict with left: np.array, right: np.array
 Returns
spl_line – dict with left: np.array, right: np.array containing the interpolated splines
 Return type
dict
pd_dt_to_s¶
lowpass_butter¶

worklab.utils.
lowpass_butter
(array, sfreq=100.0, cutoff=20.0, order=2)[source]¶ Apply a simple zerophase lowpass Butterworth filter on an array.
 Parameters
array (np.array) – input array to be filtered
sfreq (float) – sample frequency of the signal, default is 100
cutoff (float) – cutoff frequency for the filter, default is 20
order (int) – order of the filter, default is 2
 Returns
array – filtered array
 Return type
np.array
interpolate_array¶

worklab.utils.
interpolate_array
(x, y, kind='linear', fill_value='extrapolate', assume=True)[source]¶ Simple function to interpolate an array with Scipy’s interp1d. Also extrapolates NaNs.
 Parameters
x (np.array) – time array (without NaNs)
y (np.array) – array with potential NaNs
kind (str) – kind of filter, default is “linear”
fill_value (str) – fill value, default is “extrapolate”
assume (bool) – assume that the array is sorted (performance), default is True
 Returns
y – interpolated yarray
 Return type
np.array
pd_interp¶

worklab.utils.
pd_interp
(df, interp_column, at)[source]¶ Resamples (and extrapolates) DataFrame with Scipy’s interp1d, this was more performant than the pandas one for some reason.
 Parameters
df (pd.DataFrame) – target DataFrame
interp_column (str) – column to interpolate on, e.g. “time”
at (np.array) – column to interpolate to
 Returns
interp_df – interpolated DataFrame
 Return type
pd.DataFrame
merge_chars¶
find_peaks¶

worklab.utils.
find_peaks
(data, cutoff=1.0, minpeak=5.0, min_dist=5)[source]¶ Finds positive peaks in signal and returns indices of start and stop.
 Parameters
data (pd.Series, np.array) – any signal that contains peaks above minpeak that dip below cutoff
cutoff (float) – where the peak gets cut off at the bottom, basically a hysteresis band
minpeak (float) – minimum peak height of wave
min_dist (int) – minimum sample distance between peak candidates, can be used to speed up algorithm
 Returns
peaks – dictionary with start, end, and peak index of each peak
 Return type
dict
coast_down_velocity¶

worklab.utils.
coast_down_velocity
(t, v0, c1, c2, m)[source]¶ Solution for the nonlinear differential equation M(dv/dt) + c1*v**2 + c2 = 0. Returns the instantaneous velocity decreasing with time (t) for the friction coefficients c1 and c2 for an object with a fixed mass (M)
 Parameters
t (np.array) –
v0 (float) –
c1 (float) –
c2 (float) –
m (float) –
 Returns
 Return type
np.array
nonlinear_fit_coast_down¶
mask_from_iterable¶

worklab.utils.
mask_from_iterable
(array, floor_values, ceil_values)[source]¶ Combines multiple masks from iterable into one mask (e.g. can be used to select multiple time slices).
 Parameters
array (np.array) – array to apply mask on
floor_values (list) – minimum values in array
ceil_values (list) – maximum values in array
 Returns
mask
 Return type
np.array
calc_inertia¶

worklab.utils.
calc_inertia
(weight=0.8, radius=0.295, length=0.675, period=1.0)[source]¶ Calculate the inertia of an object based on the trifilar pendulum equation.
 Parameters
weight (float) – total mass of the object, default is 0.8
radius (float) – radius of the object, default is 0.295
length (float) – length of the trifilar pendulum
period (float) – observed oscillation period
 Returns
inertia – inertia [kgm2]
 Return type
float
zerocross1d¶

worklab.utils.
zerocross1d
(x, y, indices=False)[source]¶ Find the zero crossing points in 1d data.
Find the zero crossing events in a discrete data set. Linear interpolation is used to determine the actual locations of the zero crossing between two data points showing a change in sign. Data point which are zero are counted in as zero crossings if a sign change occurs across them. Note that the first and last data point will not be considered whether or not they are zero.
 Parameters
x (np.array, pd.Series) – time/sample variable
y (np.array, pd.Series) – y variable
indices (bool) – return indices or not, default is False
 Returns
position in time and optionally the index of the sample before the zerocrossing
 Return type
np.array
camel_to_snake¶
find_nearest¶

worklab.utils.
find_nearest
(array, value, index=False)[source]¶ Find the nearest value in an array or the index thereof.
 Parameters
array (np.array) – array which has to be searched
value (float) – value that you are looking for
index (bool) – whether or not you want the index
 Returns
value or index of nearest value
 Return type
np.array
binned_stats¶

worklab.utils.
binned_stats
(array, bins=10, pad=True, func=<function mean>, nan_func=<function nanmean>)[source]¶ Apply a compatible Numpy function to every bins samples (e.g. mean or std).
 Parameters
array (np.array) – array which has to be searched
bins (int) – number of samples to be averaged
pad (bool) – whether or not to pad the array with NaNs if needed
func – function that is used when no padding is applied
nan_func – function that is used when padding is applied
 Returns
means – array with the mean for every bins samples.
 Return type
np.array
Timer¶

class
worklab.utils.
Timer
(name='', text='Elapsed time: {:0.4f} seconds', start=True)[source]¶ Simple timer for timing code(blocks).
 Parameters
name (str) – name of timer, gets saved in Timer.timers optional
text (str) – custom text, optional
start (bool) – automatically start the timer when it’s initialized, default is True