numpy.ndarray不支持逻辑运算

numpy.ndarray不支持逻辑运算

今天发现ndarray能实现算数运算，但不能实现逻辑运算

如果想掩盖掉>=3且<=6的部分，如下逻辑运算是会报错的：a >= 3 and a <= 6

a = np.array([1, 2, 3, 4, 5, 6, 7])
print(a >= 3 and a <= 6)
---
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

解决方法：用算数运算代替逻辑运算，即(a >= 3) * (a <= 6)

print(f"a >= 3 : {
      a >= 3}")
print(f"a <= 6 : {
      a <= 6}")
print(f"a >= 3 and a <= 6: {
      (a >= 3) * (a <= 6)}")
print(f"range = {
      (a >= 3) * (a <= 6) * a}")

输出结果：

a >= 3 : [False False  True  True  True  True  True]
a <= 6 : [ True  True  True  True  True  True False]
a >= 3 and a <= 6: [False False  True  True  True  True False]
range = [0 0 3 4 5 6 0]