Generate fourier transform signal
You can create a sine wave in numpy.  Think of it as if you were sampling data from a signal, only you are sampling a mathematical function:

sample_rate = 1024
dt = 1.0/sample_rate
t = np.arange(sample_rate)*dt  # 1 second of samples
freq = 5
amp = 1.0
sine1 = amp*np.sin(2*np.pi*freq*t)
sine2 = .5*np.sin(2*np.pi*15*t)
sinsum = sine1 + sine2