How to average list elements in Python

I have a list L. I want to average elements of each list within this list. But I am getting an error. I present the expected output.

L=[[], [1.3342713788981633], [1.3342713788981633], [0.40896852187708455,1,3]]
L_avg=[(i+j)/len[i,j] for [i,j] in L]
print(L_avg)

The error is

in <listcomp>
    L_avg=[(i+j)/len[i,j] for [i,j] in L]

ValueError: not enough values to unpack (expected 2, got 0)

The expected output is

L_avg=[[], [1.3342713788981633], [1.3342713788981633], [(0.40896852187708455+1+3)/3]]

>Solution :

You’re getting an error because of this:

for [i,j] in L

In this way you are trying to assign elements of L to [i,j] but expressions such as [i,j]=[] or [i,j]=[1.3342713788981633] just make no sense.

Here’s what you should do instead

L=[[], [1.3342713788981633], [1.3342713788981633], [0.40896852187708455,1,3]]

L_avg = [
    [sum(x)/len(x)] if len(x)>0 else [] for x in L
]