DTMF sound in python

Can anyone help me with this error here:

  

y1 = np.sin (2 * np.pi * f1 * t)   TypeError: can not multiply sequence by non-int of type 'float'

The full code follows:

import matplotlib.pyplot as plt
import numpy as np
import pyaudio


duracao = 1.5   # em segundos
f1 = [852.0];  f2 = [1477.0]  #9
volume = 0.5     # intervalo [0.0, 1.0]


Fs = 44100       # frequencia de amostragem - DEVE SER INTEIRO
Ts = 1.0/Fs;    # intervalo de amostragem

t = np.arange(start=0,stop=duracao,step=Ts) # vetor do tempo

int (round (f1.float)) 

y1=np.sin(2*np.pi*f1*t)
y2= np.sin(2*np.pi*f2*t)

y = y1 + y2


samples = y.astype(np.float32)
p = pyaudio.PyAudio()
stream = p.open(format=pyaudio.paFloat32,
                channels=1,
                rate=Fs,
                output=True) 
stream.write(volume*samples)
stream.stop_stream()
stream.close()
p.terminate()


#Som

n = len(y) # tamanho do signal
k = np.arange(n)
T = n/Fs
frq = k/T # dois lados do range de frequencia
frq = frq[np.arange(int(n/2))] # um lado do range de frequencia

Y = np.fft.fft(y)/n # computando a Transformada de fourier e normalizando

Y = Y[range(int(n/2))]

for c in range (4):
    for r in range (3):

      y.append([f1[c], f2[r]])

tons = np.zeros([len(y)])

for i in range (len(y)):

    tons [i, :]= (y1[i][0])

    tons [i, :] += (y2[i][1])

    tons [i, :] /= 2.1 

# Teclado

D = 0; # tecla 1

D = 1; # tecla 2

D = 2; # tecla 3

D = 3; # tecla 4 

D = 4; # tecla 5 

D = 5; # tecla 6 

D = 6; # tecla 7 

D = 7; # tecla 8 

D = 8; # tecla 9 

D = 9; # tecla *

D = 10; # tecla 0

D = 11; # tecla #


tom = tons[D, :]

# plotando
fig, ax = plt.subplots(2, 1)

ax[0].plot(t[:1000],y[:1000])
ax[0].set_xlabel('Tempo')
ax[0].set_ylabel('y')

ax[1].plot(frq[:2500],abs(Y[:2500]),'r') 
ax[1].set_xlabel('Freq (Hz)')
ax[1].set_ylabel('|Y(freq)|')


# SOM DTMF
plt.title('Tecla %d' %(D+1))

plt.show();