Initialize empty matrix in Python
matlab, numpy, python
Solution
If you are using `numpy` arrays, you initialize to 0, by specifying the expected matrix size:
import numpy as np
d = np.zeros((2,3))
>>> d
[[ 0. 0. 0.]
[ 0. 0. 0.]]
This would be the equivalent of MATLAB 's:
d = zeros(2,3);
You can also initialize an empty array, again using the expected dimensions/size
d = np.empty((2,3))
If you are not using numpy, the closest somewhat equivalent to MATLAB's `d = []` (i.e., a zero-size matrix) would be using an empty list and then
append values (for filling a vector)
d = []
d.append(0)
d.append(1)
>>> d
[0, 1]
or append lists (for filling a matrix row or column):
d = []
d.append(range(0,2))
d.append(range(2,4))
>>> d
[[0, 1], [2, 3]]
See also:
initialize a numpy array (SO)
NumPy array initialization (fill with identical values) (SO)
How do I create an empty array and then append to it in NumPy? (SO)
NumPy for MATLAB users
Problem
I am trying to convert a MATLAB code in Python. I don't know how to initialize empty matrix in Python. MATLAB Code: ``` demod4(1) = []; ``` I tried in Python ``` demod4[0] = array([]) ``` but it gives error: ``` only length-1 arrays can be converted to Python scalars ```