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