英文:
How to create an array of empty lists?
问题
我在处理NumPy的内置数组时遇到了一些问题。
我有一个包含数值的列表：
l = ["a", "b", "c", "d", "e"]
列表l的长度为5，我想创建一个具有以下结构的数组。
array = [[], [], [], [], []]
内部数组的数量应该等于列表l的长度（5）。
是否有办法在NumPy中实现这个，或者是否可以使用Python内置的列表实现这个目标呢？
英文:
I'm struggling a bit with NumPy's build in arrays.
I have a list with values:
l = ["a", "b", "c", "d", "e"]
The len(l) of the list is 5 and I want to create an array with the following structure.
array = [[][][][][]]
The inner array amount should be the length of the list l. (5)
Is there any solution to this with NumPy or is there a solution doing this with the build in list from python.
答案1
得分: 1
使用Python：
array = [[] for _ in range(len(l))]
输出：[[], [], [], [], []]
使用NumPy：
array = np.zeros(shape=(len(l), 0))
输出：array([], shape=(5, 0), dtype=float64)（这与np.array([[], [], [], [], []])相同）
英文:
Using python:
array = [[] for _ in range(len(l))]
Output: [[], [], [], [], []]
With numpy:
array = np.zeros(shape=(len(l), 0))
Output: array([], shape=(5, 0), dtype=float64) (this is the same as np.array([[], [], [], [], []]))
答案2
得分: 1
使用内置列表：
n = 5
arr = [[] for x in range(n)]
arr
英文:
With bulit in list:
n = 5
arr = [[] for x in range(n)]
arr
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