practable-python

a library for connecting to experiments in python

Example Usage

import matplotlib.pyplot as plt
import numpy as np
from practable.core import Experiment
import time

messages = []
   
#modify with actual group code and experiment name
with Experiment('g-open-x3fca8','Spinner 51 (Open Days)', exact=True) as expt:
    
    # Command a step of 2 radians & collect the data
    expt.command('{"set":"mode","to":"stop"}')
    expt.command('{"set":"mode","to":"position"}')
    expt.command('{"set":"parameters","kp":1,"ki":0,"kd":0}')

    time.sleep(0.5)
        
    expt.command('{"set":"position","to":2}')    
    
    expt.ignore(0.5)
    messages = expt.collect(1.5)
    
    # Process the data
    ts = expt.extract_series(messages, "t")
    ds = expt.extract_series(messages, "d")
    cs = expt.extract_series(messages, "c")
    
    t = np.array(ts)
    t = t - t[0]
    
    # Plot the data
    plt.figure()        
    plt.plot(t/1e3,ds,'-b',label="position")
    plt.plot(t/1e3,cs,':r',label="set point")
    plt.xlabel("time(s)")
    plt.ylabel("position(rad)")
    plt.legend()

This script produces the following text output

Command: {"set":"mode","to":"stop"}
Command: {"set":"mode","to":"position"}
Command: {"set":"parameters","kp":1,"ki":0,"kd":0}
Command: {"set":"position","to":2}
Ignoring messages for 0.5 seconds |██████████████████████████████████████████████████| 100.0% Complete

Collecting messages for 1.5 seconds |██████████████████████████████████████████████████| 100.0% Complete

An a graph:

Additional information

A user name is obtained and stored locally.

Bookings last only as long as the experiment is needed, because they are cancelled when the with environment exits. The default booking duration is 3 min.

You can use an existing booking by specifying user="cxxxxxxxxxx" where the username is found on the user tab of the booking system that holds the booking.

Other practable instances can be accessed by specifying it e.g. booking-server="https://some.booking.server"

Requirements

Recommend python >= 3.8 because we're using websockets 12.0