How to plot sine wave in Python with sudden amplitude change?

Question

Posted: 7/4/2020

I was wondering if anyone knows how to plot a sine wave with let\'s say amplitude of 0.1 as a start and then continuing on as usual. Until at one point,

Answer 1

I have converted the code to period time:

import matplotlib.pyplot as plt
import math


# ------------------------------------------------------------------------
# uses the list amplitude_changes to get the amplitude for time t
def get_amplitude(t):
    for amplitude_change in amplitude_changes:
        if t >= amplitude_change['t']:
            amplitude = amplitude_change['amplitude']

    return amplitude


# --------------------------------------------------------------------------
def y_func(time, period_time, amplitude):
    return amplitude * math.sin((time / period_time) * 2 * math.pi)

# --------------------------------------------------------------------------


t_values = []
amplitude_values = []

signal1Frequency = 50
period_time = 1 / signal1Frequency
sampling_frequency = 1500

delta_t = 1 / sampling_frequency


amplitude_changes = [
                        {'t': 0, 'amplitude': 1},
                        {'t': period_time * 0.9, 'amplitude': 1.5},
                        {'t': period_time * 0.95, 'amplitude': 1},
                        {'t': period_time * 1.2, 'amplitude': 0.8},
                        {'t': period_time * 1.25, 'amplitude': 1},
                    ]

max_t = period_time * 3                     # plot 3 periods
t = 0
while t <= max_t:
    t_values.append(t)
    amplitude = get_amplitude(t)
    amplitude_values.append(y_func(t, period_time, amplitude))
    t += delta_t


plt.plot(t_values, amplitude_values)
plt.title(f'f = {signal1Frequency} Hz (T = {period_time}) - Sampling frequency = {sampling_frequency} Hz')
plt.show()

Result