108 lines
2.1 KiB
Python
108 lines
2.1 KiB
Python
|
|
|
|
import numpy as np
|
|
# # 使用标量类型
|
|
# dt = np.dtype(np.int32)
|
|
# print(dt)
|
|
#
|
|
# # int8, int16, int32, int64 四种数据类型可以使用字符串 'i1', 'i2','i4','i8' 代替
|
|
# dt = np.dtype('i4')
|
|
# print(dt)
|
|
#
|
|
# # 字节顺序标注
|
|
# dt = np.dtype('<i4')
|
|
# print(dt)
|
|
#
|
|
# dt = np.dtype([('age', np.int8)])
|
|
# print(dt)
|
|
#
|
|
# dt = np.dtype([('age', np.int8)])
|
|
# a = np.array([(10,), (20,), (30,)], dtype=dt)
|
|
# print(a)
|
|
# print(a['age'])
|
|
#
|
|
# student = np.dtype([('name', 'S20'), ('age', 'i1'), ('marks', 'f4')])
|
|
# print(student)
|
|
#
|
|
# a = np.array([('abc', 21, 50), ('xyz', 18, 75)], dtype=student)
|
|
# print(a)
|
|
#
|
|
# a = np.arange(32)
|
|
# b = a.reshape(2, 4, 4)
|
|
# print(b.ndim)
|
|
# print(b.shape)
|
|
#
|
|
# a = np.array([[1, 2, 3], [4, 5, 6]])
|
|
# a.shape = (3, 2)
|
|
# print(a)
|
|
#
|
|
# a = np.array([[1, 2, 3], [4, 5, 6]])
|
|
# b = a.reshape(3, 2)
|
|
# print(b)
|
|
# x = np.array([1, 2, 3, 4, 5], dtype=np.int8)
|
|
# print(x.itemsize)
|
|
# y = np.array([1, 2, 3, 4, 5], dtype=np.float64)
|
|
# print(y.itemsize)
|
|
|
|
# x = np.empty([3, 2], dtype=int)
|
|
# print(x)
|
|
#
|
|
# # 默认为浮点数
|
|
# x = np.zeros(5)
|
|
# print(x)
|
|
# # 设置类型为整数
|
|
# y = np.zeros((5,), dtype=int)
|
|
# print(y)
|
|
#
|
|
# # 自定义类型
|
|
# z = np.zeros((2, 2), dtype=[('x', 'i4'), ('y', 'i4')])
|
|
# print(z)
|
|
#
|
|
# # 默认为浮点数
|
|
# x = np.ones(5)
|
|
# print(x)
|
|
#
|
|
# x = np.ones([2, 2], dtype=int)
|
|
# print(x)
|
|
#
|
|
# s = b'Hello World'
|
|
# a = np.frombuffer(s, dtype='S1')
|
|
# print(a)
|
|
#
|
|
# arr1 = np.array([1, 2, 3, 4, 5])
|
|
# arr2 = np.frombuffer(arr1, dtype=int)
|
|
# print(arr2) # [1 2 3 4 5]
|
|
#
|
|
#
|
|
# list=range(5)
|
|
# it=iter(list)
|
|
# a = [1,2,3,4,5]
|
|
# # 使用迭代器创建 ndarray
|
|
# x=np.fromiter(arr1, dtype=float)
|
|
# print(x)
|
|
# aa = [
|
|
# [1, 2, 3],
|
|
# [4, 5, 6],
|
|
# [7, 8, 9]
|
|
# ]
|
|
# a = np.array(aa)
|
|
# # b = a[1:3, 1:3]
|
|
# # c = a[1:3, [1, 2]]
|
|
# d = a[...,1:]
|
|
# # print(b)
|
|
# # print(c)
|
|
# print(d)
|
|
|
|
# a = np.array([[0, 0, 0],
|
|
# [10, 10, 10],
|
|
# [20, 20, 20],
|
|
# [30, 30, 30]])
|
|
# b = np.array([1, 2, 3])
|
|
# bb = np.tile(b, (4, 1)) # 重复 b 的各个维度
|
|
# print(bb)
|
|
# # print(a + bb)
|
|
|
|
a = np.arange(6).reshape(2, 3)
|
|
print(a)
|
|
print("========================")
|
|
print(a.T) |