如何创建一个列表长度为零的numpy数组？

Question

I have a list, say

a = [3, 4, 5, 6, 7]

And i want to create a numpy array of zeros of that list's length.

If I do

b = np.zeros((len(a), 1))

I get

[[0, 0, 0, 0, 0]]

instead of

[0, 0, 0, 0, 0]

What is the best way to get the latter option?

Answer 1

If you don't want to have to care about shapes, use np.zeros_like :

np.zeros_like(a)
# array([0, 0, 0, 0, 0])

---

There's also the option of querying np.shape :

np.zeros(np.shape(a))
# array([0., 0., 0., 0., 0.])

Both options should work for ND lists as well.

Answer 2

You passed two-element tuple to zeros , so it produced 2D array, you can simply pass integer to zeros

a = [3, 4, 5, 6, 7]
b = np.zeros(len(a))
print(b) #prints [ 0.  0.  0.  0.  0.]

Answer 3

You can try this

np.zeros(len(a), dtype=np.int)

It will return

array([0, 0, 0, 0, 0])