Python: 對純量(整數int,浮點數float)取list()跟array()會如何? numpy.array(scalar) ; list(scalar), 2D array的運算

程式碼:

a = 1
lsta = list(a)

print(lsta,type(lsta),len(lsta))

輸出:

Traceback (most recent call last):

File “C:\Python\Radar_20221005\untitled1.py”, line 3, in <module>
lsta = list(a)

TypeError: ‘int’ object is not iterable

int無法取list()

 

如果取array()呢?

程式碼:

import numpy as np
a = 1
arya = np.array(a)

print(arya, type(arya), len(arya))

輸出:

Traceback (most recent call last):

File “C:\Python\Radar_20221005\untitled1.py”, line 7, in <module>
print(arya,type(arya),len(arya))

TypeError: len() of unsized object

int可以取array(),

只是長度0 (不要誤會長度1)

所以取len()時錯誤

empty list: []長度也是0

 

去掉len()

3(1+2)的左右邊沒有[ ] 包覆

type為ndarray (0-dimensional)

用法同int

 

numpy官網:

2D array的運算:

 

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