Invalid Number of Arguments when trying to add arrays inside a list using python - python-3.x

Question

I am trying to understand why I get invalid number of argument in the below code and if there is a way to fix it.
here is the code:
import numpy as np
acc_reading = []
a = np.array([0.11e+00, 1.11e-08, 1.11e-02])
b = np.array([0.12e+00, 1.22e-08, 2.22e-02])
c = np.array([3.11e+00, 3.18e-08, 3.33e-02])
d = np.array([3.41e+00, 4.18e-08, 4.31e-02])
e = np.array([0.55e+00, 1.55e-08, 5.31e-02])
f = np.array([0.66e+00, 1.66e-08, 3.66e-02])
g = np.array([0.66e+00, 1.66e-08, 3.66e-02])
h = np.array([0.66e+00, 1.66e-08, 3.66e-02])
ab = np.add(a,b)
cd = np.add(c, d)
ef = np.add(e, f)
i = np.add(g, h)
acc_reading.append(ab)
acc_reading.append(cd)
acc_reading.append(ef)
acc_reading.append(i)
kk = np.add(acc_reading[0], acc_reading[1], acc_reading[2], acc_reading[3])
The output of the above code is:
ValueError: invalid number of arguments

Answer 1

Read the docs for np.add and np.sum
Your lists - 4 terms of size 3
In [213]: acc_reading
Out[213]:
[array([2.30e-01, 2.33e-08, 3.33e-02]),
array([6.52e+00, 7.36e-08, 7.64e-02]),
array([1.21e+00, 3.21e-08, 8.97e-02]),
array([1.32e+00, 3.32e-08, 7.32e-02])]
sum all values to one:
In [214]: np.sum(acc_reading)
Out[214]: 9.5526001622
sum rows and columns - treating acc_reading as (3,4) array:
In [215]: np.sum(acc_reading, axis=0)
Out[215]: array([9.280e+00, 1.622e-07, 2.726e-01])
In [216]: np.sum(acc_reading, axis=1)
Out[216]: array([0.26330002, 6.59640007, 1.29970003, 1.39320003])
Your attempt to use np.add (which you used correctly earlier)
In [217]: np.add(acc_reading[0], acc_reading[1], acc_reading[2], acc_reading[3])
...:
Traceback (most recent call last):
File "<ipython-input-217-52b8f942b588>", line 1, in <module>
np.add(acc_reading[0], acc_reading[1], acc_reading[2], acc_reading[3])
TypeError: add() takes from 2 to 3 positional arguments but 4 were given
giving it just 2 arrays:
In [218]: np.add(acc_reading[0], acc_reading[1])
Out[218]: array([6.750e+00, 9.690e-08, 1.097e-01])
a more direct way:
In [220]: arr = np.array([a+b, c+d, e+f, g+h])
In [221]: arr
Out[221]:
array([[2.30e-01, 2.33e-08, 3.33e-02],
[6.52e+00, 7.36e-08, 7.64e-02],
[1.21e+00, 3.21e-08, 8.97e-02],
[1.32e+00, 3.32e-08, 7.32e-02]])
In [222]: arr.sum()
Out[222]: 9.5526001622