Invalid float error while integrating using integrate.quad - python-2.7

Question

I have a list:
q1 = [0,1.9488e-06,1.5473e-05,5.1829e-05,0.00012192,0.00023633,0.00040526,0.00063862,0.00094596,0.0013365,0.0018192,0.0024025,0.0030949,0.0039041,0.0048379,0.0059036]
which I am trying to integrate.
I have done the following:
def f(x):
if (np.abs(x)<1e-10):
res = x
else:
res = q2[:10]
return res
x = np.arange(0,10,0.001)
def F(x):
res = np.zeros_like(x)
for i,val in enumerate (x):
y,err = integrate.quad(f,0,val)
res[i] = y
return res
plt.plot(F(x))
when I try to run this code I get this error:
Traceback (most recent call last):
File "<ipython-input-88-ca3005760f4b>", line 19, in <module>
plt.plot(F(x))
File "<ipython-input-88-ca3005760f4b>", line 14, in F
y,err = integrate.quad(f,0,val)
File "C:\Anaconda2\lib\site-packages\scipy\integrate\quadpack.py", line 311,
in quad points)
File "C:\Anaconda2\lib\site-packages\scipy\integrate\quadpack.py", line 376,
in _quad
return _quadpack._qagse(func,a,b,args,full_output,epsabs,epsrel,limit)
error: Supplied function does not return a valid float.
Can anyone help me understand why I am getting this error?

Answer 1

You're having this error because of these two lines in f:
else:
res = q2[:10]
Here, you're returning a slice of a list from the function. quad doesn't like that; according to its documentation, it expects a function that returns a double (i.e. Python float), not a list.
While your intended output isn't given in your question, changing that line to
res = q2[0]
or any other arbitrary index in q2 corrects the error.